Fishing district boundaries:Čiastkové povodie Dudváhu od ústia Čiernej vody po ústie Gidry pri obci Malá Mača, potok Šárd od hate VN Šárd po sútok Salibským Dudváhom, Salibský Dudváh od ústia pri obci Čierny Brod po sútok s Čiernou vodou, kanál Pena od ústia
Fishing conditionsFish activity indexOur calculation (0–100): the base is set by water temperature, adjusted by light, turbidity, oxygen, weather and other factors according to how well they are supported by studies. For each factor you can see the confidence and the source. A planning aid, not a bite forecast.
The score, the best window of the day and what pushes it up or down
Fishing conditions
Fish activity indexOur calculation (0–100): the base is set by water temperature, adjusted by light, turbidity, oxygen, weather and other factors according to how well they are supported by studies. For each factor you can see the confidence and the source. A planning aid, not a bite forecast.
Loading data…
Water
Water level, temperature, modelled flow and gradient
Water level
Water levelThe water level at the nearest SHMÚ gauge in centimetres above the gauge zero. It is the water level at the station, not the depth of the water at the fishing district.
Čierny Brod – Dudváh · level stable
The water level is stable.Water level trendSlightly rising water washes food out of the banks and activates fish, which move into slacks and behind obstacles. Rapid rising brings turbidity and fish do not bite; falling water after a flood often dampens bites. A stable water level is usually pleasant for fishing, and fish keep settled holding places.
Water level at the gauge, last days (cm)Water level trend: from 6 Nov 13:45 to 7 Nov 13:45. Latest 21 cm, lowest 21, highest 21 cm.
The level is measured at an SHMÚ gauge; it is not the depth of the water in the fishing district. The coloured lines are flood-activity degreesFlood activity degreesSHMÚ declares three degrees for water gauges: degree 1 vigilance, degree 2 alert, degree 3 danger. At a higher degree fishing is dangerous..
Water temperature
Water temperatureFish are cold-blooded and water temperature governs their digestion. Below 8 °C metabolism slows down, activity peaks at 15–22 °C, above 25 °C oxygen drops.
0815222530°C
Cold water. The fish's metabolism is slowed. Fine baits and a minimum of feed help.
Water temperature, last days (°C)Water temperature trend: from 6 Nov 13:45 to 7 Nov 13:45. Latest 6.5 °C, lowest 5.7, highest 7.9 °C.
Below 8 °C: slowed metabolism
8–15 °C: activity rises
15–22 °C: peak feeding activity
22–25 °C: activity drops
Above 25 °C: little oxygen
Modelled flow
Modeled flowAn estimate of the amount of water in the river (m³/s) from the GloFAS model, not a measurement. The resolution is about 5 km, so on small streams it may show a larger river nearby.
Loading data…
Elevation profile of the watercourse
Elevation profileHow the altitude of the watercourse changes downstream. It is calculated from a digital relief model (tens of metres), not from a water-level measurement, so it is approximate, especially for narrow streams.
Slow watercourseA lowland river with a calm current, shallows along the banks and deeper pools in the bends.
Elevation profile of the fishing district downstream: from 132 to 113 m a.s.l. over 40.9 km.Downstream, from the upper end of the fishing district (left) to the lower end
Highest point
133 m a.s.l.
Lowest point
111 m a.s.l.
FallFallThe difference in altitude between the upper and lower end of the fishing district in metres. The greater the fall over a shorter length, the faster the water.
22 m
SlopeWatercourse gradientFall per kilometre in per mille (‰, metres per kilometre). Up to 2 ‰ is a slow lowland river, 5 to 10 ‰ a foothill river (grayling, trout), above 10 ‰ a fast stream.
0.5 ‰
SinuositySinuosityThe length of the watercourse divided by the straight-line distance between its ends. 1.0 is a straight watercourse; above 1.3 it meanders strongly. Meanders create pools under the banks and shallows in the reaches between.
1.39
Weather and forecast
Hour by hour, pressure and the next few days
Weather and forecast
Loading data…
Sky: sun, moon and solunar windowsSolunar periodsCalculated from the position of the Moon: major periods (about 2 h) around the Moon's passage above and below the horizon, minor periods (about 1 h) around moonrise and moonset. A scientifically unconfirmed theory: in a study of 361 fishing trips (Quigley et al. 2023) it did not predict bites. We treat it as a hypothesis with a weight of at most ±2 points.
Where the sun and moon are right now and when the best windows of the day will come
Sky: sun and moon
Solunar periodsCalculated from the position of the Moon: major periods (about 2 h) around the Moon's passage above and below the horizon, minor periods (about 1 h) around moonrise and moonset. A scientifically unconfirmed theory: in a study of 361 fishing trips (Quigley et al. 2023) it did not predict bites. We treat it as a hypothesis with a weight of at most ±2 points.
Drag along the axis to see where the sun and moon will be.
Sun
Moon
Golden hour
Main period
Minor period
Sun
Dawn06:10
Sunrise06:43
Sunset16:21
Dusk16:54
The day lasts 9 h 39 min.
MoonMoon phaseAt full and new moon the gravitational effect is strongest. On a clear full-moon night predators and carp often feed at night, and the day after may be weaker.
Waning crescent6% illuminated
Sunrise04:44
Sunset15:04
Full moon around 24 Nov, new moon around 9 Nov.
Windows of the daySolunar periodsCalculated from the position of the Moon: major periods (about 2 h) around the Moon's passage above and below the horizon, minor periods (about 1 h) around moonrise and moonset. A scientifically unconfirmed theory: in a study of 361 fishing trips (Quigley et al. 2023) it did not predict bites. We treat it as a hypothesis with a weight of at most ±2 points.
Minor solunar period04:14–05:14
Golden hour (morning)06:13–07:43
Main solunar period09:00–11:00
Minor solunar period14:34–15:34
Golden hour (evening)15:21–16:51
Main solunar period21:22–23:22
Solunar theory is not scientifically confirmed; we treat it as a supplement. The golden hour is the time around sunrise and sunset, when fish often bite.
Map and fishing district data
Course of the water, spots along the water, character and basic data
DepthDepthThe greatest depth from the fishing district description. Shallows warm up quickly and are rich in food; deep pools give shelter and a more stable temperature.0.8–2.0 m
BottomBottomThe bottom material determines which fish live here and where they find food. Fish zones can be recognized by the bottom: rocky, gravelly, sandy to muddy.muddy, locally muddy
Watercourse lineWatercourse lineThe shape of the watercourse seen from above. In bends there is a deep scour under the outer bank and a shallow bar under the inner one; a winding stream has more shelter and changes in depth.undulating
ShadingShadingThe share of the water surface in shade. Shade lowers summer water temperatures and supplies insects and shelter; a sunny section warms up faster and becomes more overgrown.0%
VegetationVegetationTree and herbaceous vegetation on the banks. Roots and branches create shelter, and leaves and twigs falling in provide food. It also determines where you can cast and where your rig gets snagged.grassy
Cross-channel structuresCross-channel structuresWeirs, steps and dams hold back water and stop fish from migrating. Below them a deep plunge pool with oxygenated water forms.none
What this means for anglersexplanation of the bottom, vegetation, watercourse line and other data of this fishing district
Depth: Medium, 1–3 m
The most common type: shallows alternate with deeper spots and fish move according to the time of day and temperature.
Bottom: Muddy bottom
Slow lowland waters and carp fishing districts. Mud hides food, but in summer there may be less oxygen near the bottom, and lures sink into it.
Watercourse line: Undulating line
Pronounced bends. Under the outer bank there is usually a deep hole, on the inner side a shallow gravel or sand bar.
Shade: Sunny, up to 10% shade
In summer the water warms up quickly and aquatic plants and algae thrive here. At midday fish move to deeper places.
Vegetation: Grassy bank
Open and easily accessible, but with fewer hiding places. Fish stay in deeper water and by obstacles further from the bank.
Cross-channel structures: none
Fish can move freely along the watercourse; the section is more continuous.
The explanation is general and based on the fishing district description in the data and on common fishing practice. Actual conditions on site may differ; check them before you fish.
Confluences and risk spots
COV GalantaWastewater discharge point
0.0 km
COV Horne SalibyWastewater discharge point
0.0 km
COV SladkovicovoWastewater discharge point
0.0 km
COV Velka MacaWastewater discharge point
0.0 km
COV Horne SalibyWastewater treatment plant · capacity 3,100 PEThe treatment plant is overloaded (151% of capacity)Details
Closed season, fishing hours, minimum sizes and daily limit. For guidance only: check them in the fishing regulations of the fishing district
Closed season for all fish
§ 13, paragraphs 3 and 5 of the Act
15 Mar – 31 May
JanFebMarAprMayJuneJulyAugSepOctNovDec
today
fishing for all fish prohibitedoutside this period
The ban does not apply 1 May – 31 May during fishing competitions (§ 13, para. 3). It also does not apply to carp waters that are watercourses (but not reservoirs, dead-end, dead and cut-off arms), or to other water bodies (§ 13, para. 5). Check in the fishing regulations of the district which case your district is.
The protection periods by species (below) apply independently of this closed season.
Daily fishing hours
§ 11 of the Decree
Applies only outside the closed season. Outside these hours fishing is prohibited (§ 14(b) of the Act).
06121824 h
January to April, November, December6.00 – 21.00 h
May4.00 – 24.00 h
June to October0.00 – 24.00 h
Months missing from the table fall within the closed season. The hours in November and December on trout and grayling waters relate to the exception for fishing huchen (§ 13, para. 4 of the Act); check in the fishing regulations what may be caught at that time. On border waters the hours in the permit or the fishing regulations apply (§ 11, para. 2 of the Decree). The Act regulates night fishing in two wordings that seem to contradict each other at first sight, so always ask about it in the fishing regulations of the district or the fishing guard.
2ksGreen groupeel, carp, burbot, zander, pike, tench, barbel, lake brown trout, brown trout, grayling (combined)
4ksYellow grouprainbow trout, brook trout, common nase, vimba bream; added to the green or blue group (at most 4 fish in total)
5kgOther speciesfor example crucian carp, breams, dace and chub (combined); invasive species are not counted
The blue and green groups cannot be combined. The limit applies per day, also when fishing in several districts, and once it is reached, fishing for that day ends. The species groups follow the SRZ interpretation of January 2026, not the text of the section directly. The district user may set a lower limit in the permit, in which case the stricter one applies.
Protection periods by species§ 10 of the Decree
During this period the species must not be caught, even if the water type otherwise allows fishing at that time. It applies independently of the closed season for all fish.
1 Jan – 15 Mar
burbot
1 Jan – 31 May
grayling, spirlin, northern pike
1 Jan – 15 Jun
wels catfish, zander (pikeperch), Volga pikeperch
1 Jan – 31 Oct
huchen (in border waters 1 Jan – 31 Aug)
15 Mar – 31 May
common carp in carp waters (does not apply 1 – 31 May during competitions, nor on other water bodies); asp, chub, dace, ide, sterlet, Siberian sturgeon, tench, barbel, vimba bream, zope, white-eye bream, common bream, common nase
1 Sep – 15 Apr
brown trout, brown trout (lake form)
1 Sep – 28 Feb
peled
Some species are protected all year round (for example zingel and streber, lampreys, gudgeons, spined loaches, maraena whitefish, Carpathian barbel, sabre carp) and fishing for them is always prohibited. The full list of species is in the guide The fishing law, rule by rule.
Minimum sizes§ 12 of the Decree
The shortest length from which you may keep a fish. The district user may raise the size, so look for the valid value in the permit and the fishing regulations.
grass carp60 cm
black carp60 cm
asp40 cm
huchen (Danube salmon)80 cm
chub25 cm
dace20 cm
ide30 cm
sterlet45 cm
Siberian sturgeon45 cm
common carp40 cm
tench30 cm
grayling33 cm
burbot35 cm
barbel40 cm
vimba bream30 cm
zope (blue bream)25 cm
white-eye bream25 cm
common bream30 cm
silver bream15 cm
common nase30 cm
rainbow trout27 cm
brown trout (lake form)50 cm
brown trout27 cm
peled25 cm
brook trout27 cm
wels catfish70 cm
northern pike60 cm
silver carp45 cm
bighead carp45 cm
European eel50 cm
zander (pikeperch)50 cm
Volga pikeperch35 cm
Total length is measured from the front of the head to the end of the longest ray of the tail fin (§ 12, para. 4). No minimum size applies, for example, to sunbleak, Prussian carp, European perch, roach, loach (slíž severný) and invasive species.
Before and after fishing
Carry your fishing license and permit while fishing and show them when checked (§ 12 of the Act). Check that they are valid.
Before you start fishing, write down the date and the district number (no. 2-0410-1-1); after fishing, write down the number and weight of your catch (§ 14(d) of the Act). Fishing without a record is an offense.
Prohibited fishing methods, night fishing, competitions and other rules are covered in the guide The fishing law, rule by rule.
As of 6 Nov 2026: Act no. 216/2018 Coll. on fisheries (wording effective 1 Jan 2022) and Decree no. 381/2018 Coll. (wording effective 1 Jan 2019); we found no newer wording. The law may change; you can find the current wording on Slov-Lex (Act) and Slov-Lex (Decree).
News from the organization and catches from the fishing district
Catches from the fishing district
Nobody has recorded a catch in this fishing district yetBe the first: after approval it will also appear here in the ranking.
Water quality, river basin, bottom, fish, aquatic insects, wildlife and hazards from open databases. Except for wildlife and hazards, they are also included in the activity score.
What follows from this
Public sources in the conditions scoreData on oxygen, nutrients, reservoir depth, watercourse size, bottom, fish species and insect swarming slightly adjust the "Fishing conditions" score. Each adjustment is shown separately in the score breakdown.
Public data about this water lower the activity score.
Biggest deduction: Invasive species nearby −2
We assessed 15 factors; 6 of them change the score. The adjustments range from −14 to +12 points so that they do not outweigh the weather and water temperature. They are counted in the score, in the ranking and in the filters.
Water and oxygen−1
Water temperature for local speciesLevel of evidence: Partly supported
The water temperature is outside what these species prefer, so they are less active.
What we know about it
We compare the temperature requirements of species (FishBase; for salmonids Elliott and Elliott 2010) with the water temperature for species recorded near the water (GBIF). A species recorded nearby does not necessarily live in this very water, so this is only partly supported.
Sources: Elliott and Elliott 2010
−1
Pollution−3
Harmful substances in groundwater (SHMÚ)Level of evidence: Partly supported
metals and metalloids (above the standard at 1 of 8 stations), highest value 1 times the standard
Metals, pesticides, PFAS and chlorinated solvents above the standard show the burden on the surroundings. The standards are set for drinking water and are stricter than the limits harmful to fish, so the reduction is small; metals can also come from rocks. PAHs are not counted in the score. Data reliability is 100% (8 stations within 10 km, the nearest 0.4 km, data from 2025); the adjustment was applied in full.
What we know about it
Metals and metalloids, pesticides, PFAS and chlorinated solvents above the standard at stations within 10 km. The standards are drinking-water standards and stricter than the limits harmful to fish, so the reduction is small: one point for one or two groups of substances, two points for three groups or for a value at least five times above the standard. Metals are poisonous to fish, more so in soft water (Pagenkopf 1983), and PFAS accumulate in tissues (Giesy and Kannan 2001); metals can also come from rocks. PAHs are not counted. The adjustment is multiplied by the reliability of the data.
Sources: SHMÚ, groundwater; Pagenkopf 1983; Giesy and Kannan 2001
−1
Iron in groundwater (SHMÚ)Level of evidence: Partly supported
iron typically 2.62 mg/l (standard 0.2)
Dissolved iron precipitates when groundwater emerges into the air and clogs gills, gravel with eggs and invertebrate shelters. Data reliability is 100% (8 stations within 10 km, the nearest 0.4 km, data from 2025); the adjustment was applied in full.
What we know about it
Dissolved iron precipitates when groundwater emerges into the air and clogs gills, egg-bearing gravel and the shelters of invertebrates (Vuori 1995). It is counted at a typical value of at least 1 mg/l (five times the standard); the adjustment of −1 is multiplied by the reliability of the data.
Sources: SHMÚ, groundwater; Vuori 1995
−1
Wastewater treatment plants near the fishing districtLevel of evidence: Anglers' practice
WWTP Horne Saliby, 0.1 km: load 151%
A treatment plant that does not meet the requirements of Directive 91/271/EEC or is overloaded may discharge more nutrients and organic matter into the watercourse. The treatment plant need not lie upstream of the fishing district (we do not assess the watercourse), so the weight is small.
What we know about it
A treatment plant within 2 km of the fishing district that does not meet the requirements of Directive 91/271/EEC or is overloaded above 100% of capacity. The plant need not lie upstream of the fishing district, so the weight is only −1 to −2 points.
Sources: Directive 91/271/EEC
−1
Life by the water−2
Aquatic insect hatchesLevel of evidence: Anglers' practice
0.0× the average month, 0 of 45 observations in the year, iNaturalist
Aquatic insects are scarce this month; food near the bottom matters more.
What we know about it
Anglers fish "by the insects" (dry and wet fly). A measured relationship between catches and insect hatches is not documented in our sources.
0
Invasive species nearbyLevel of evidence: Anglers' practice
topmouth gudgeon, round goby, pumpkinseed, GBIF
Invasive species displace native fish and occupy shallows. The score reduction is only small.
What we know about it
Invasive species displace native fish. The score reduction is only small.
−2
Do not change the score
Data for these factors is missing or within the normal range:
Dissolved oxygen
Nutrients in the water
Water acidity (pH)
Ammonium ions in water
Surface water (SHMÚ)
Nitrogen in groundwater
Chlorides in groundwater
Watercourse size
Bottom by geology
The rules are indicative and based on fishing practice and scientific studies; for each factor you can see how well it is supported. Weather, air pressure and water temperature affect the score more than this data does.
Water pollution
Water pollution (SHMÚ)Water quality indicators that fail the standards at the nearest monitoring site on the same watercourse in the SHMÚ yearbooks for 2022 to 2025.
Groundwater nearby
1 of 8stations with substances from human activity, 2025
Nitrates in groundwater
1.9 mg/ltypical value from 8 stations within 10 km, within the standard, 2025
Treatment plants within 2 km
41 of them fail the requirements or are overloaded
The data comes from the SHMÚ yearbooks (surface waters 2022 to 2025). The yearbook lists the sites that failed the standard; a site missing from the yearbook is not considered clean. We determine the distance and the match of the watercourse name ourselves, so the assignment is indicative.
Groundwater nearby
Groundwater nearby (SHMÚ)Measured groundwater values from stations within 10 km of the fishing district (nitrates, harmful substances, ammonium, iron, chlorides) and the SHMÚ yearbooks.
Groundwater within 10 km (8 stations)
SeredGalanta district · borehole or well · 0.4 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Total iron
Conductivity at 20 °C
Sulfates
Measured values, year 2025, sampling 30 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates< 1 mg/l
Ammonium0.28 mg/l
Nitrites< 0.01 mg/l
Iron4.15 mg/l
Chlorides95.2 mg/l
Aluminium85% of the standard
GalantaGalanta district · borehole or well · 0.6 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Total iron
Measured values, year 2025, sampling 10 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates1.9 mg/l
Ammonium0.11 mg/l
Nitrites0.05 mg/l
Iron3.01 mg/l
Chlorides68.8 mg/l
Nickel95% of the standard
propisochlor20% of the standard
Sered-maly HajGalanta district · borehole or well · 0.6 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Conductivity at 20 °C
Sulfates
Measured values, year 2025, sampling 30 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates12.6 mg/l
Ammonium< 0.01 mg/l
Nitrites< 0.01 mg/l
Iron0.081 mg/l
Chlorides124 mg/l
Aluminium70% of the standard
Show 5 more
VlckovceTrnava district · borehole or well · 0.8 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Total iron
Conductivity at 20 °C
Measured values, year 2025, sampling 30 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates27.5 mg/l
Ammonium0.41 mg/l
Nitrites0.05 mg/l
Iron1.64 mg/l
Chlorides97.5 mg/l
Aluminium80% of the standard
Horne Saliby-dolna LukaGalanta district · borehole or well · 0.8 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Total iron
Measured values, year 2025, sampling 2 Oct 2025 (2 samplings, the highest value of the year for each substance):
Nitrates< 1 mg/l
Ammonium0.25 mg/l
Nitrites< 0.01 mg/l
Iron2.62 mg/l
Chlorides49.9 mg/l
Arsenic67% of the standard
Soporna-strkovecGalanta district · borehole or well · 1.3 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Total iron
Sulfates
Chromium
Measured values, year 2025, sampling 10 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates< 1 mg/l
Ammonium0.23 mg/l
Nitrites0.02 mg/l
Iron0.98 mg/l
Chlorides41.3 mg/l
Chromium104% of the standard
Sered-dolna StredaGalanta district · borehole or well · 1.3 km from the fishing district
substances from human activity
2017 to 2025
Exceeded in 2025:
Manganese
Ratio of NO3 to NO2
Nitrates
Conductivity at 20 °C
Measured values, year 2025, sampling 18 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates112 mg/l
Ammonium< 0.01 mg/l
Nitrites0.03 mg/l
Iron0.002 mg/l
Chlorides205 mg/l
Aluminium95% of the standard
Topolnica – MatuskovoGalanta district · borehole or well · 1.8 km from the fishing district
natural substances only
2017 to 2025
Exceeded in 2025:
Manganese
Total iron
Measured values, year 2025, sampling 9 Sep 2025 (2 samplings, the highest value of the year for each substance):
Nitrates< 1 mg/l
Ammonium0.47 mg/l
Nitrites0.02 mg/l
Iron3.02 mg/l
Chlorides66.9 mg/l
Aluminium95% of the standard
substances from human activity
natural substances only
no exceedance recorded
Groundwater reaches streams as base flow, so the connection to the stream at the fishing district is only indirect. Natural substances (iron, manganese, sulfates, conductivity) are not counted in the yearbook-based assessment.
The data comes from the SHMÚ yearbooks (groundwater 2017 to 2025).
Wastewater treatment plants
Wastewater treatment plants near the fishing districtPlants within 2 km of the district: overload, compliance with EU requirements and discharged load (BOD₅, COD, nitrogen, phosphorus in tonnes per year).
COV Horne Saliby0.1 km from the fishing district · capacity 3,100 PE · mechanical, biological, nitrogen removal
overloaded
151% of capacity
COV Galanta0.2 km from the fishing district · capacity 45,000 PE · mechanical, biological, nitrogen and phosphorus removal
within the standard
34% of capacity
COV Sladkovicovo0.7 km from the fishing district · capacity 7,500 PE · mechanical, biological, nitrogen removal
within the standard
100% of capacity
COV Velka Maca0.8 km from the fishing district · capacity 200 PE · mechanical, biological
within the standard
31% of capacity
Treatment plants within 2 km of the fishing district. The treatment plant need not lie upstream of the fishing district; we do not assess the watercourse at the plant. Load is the ratio of the pollution produced to the capacity of the treatment plant (PE = population equivalent).
River basin and reservoir
Reservoir depth (HydroLAKES)Average depth, volume and water retention time in the reservoir from the HydroLAKES database (WWF). The depth is estimated by a model from the surrounding terrain, so it is approximate.
Watercourse from the HydroRIVERS databasematched with the fishing district, line deviation about 17 m
Catchment above the spotWatercourse size (HydroRIVERS)The catchment area above the spot, the stream order and the average flow from the HydroRIVERS database (WWF). It determines whether it is a stream, a river or a large river.
97 km²stream
Average flow
0.33 m³/smodel value
Stream order (Strahler)
1upper course, small tributary
Channel gradient
0.5 ‰Slow watercourse
The data come from a global database with a coarser resolution (tens of metres), so they are only approximate for small waters. Depth and volume are model averages.
Bottom and bedrock
Bottom and bedrock (ŠGÚDŠ)The bedrock under the water according to the hydrogeological map of Slovakia at 1 : 50,000 (ŠGÚDŠ). It tells whether the surroundings are gravelly, sandy, clayey, muddy or rocky.
Clays and loams
After rain the water quickly turns turbid and fish hunt more by smell.
Gravels 11%
Clays and loams 67%
Fine-grained, muddy 22%
Springs and outflows
0none within 1 km
According to the geological map: fluviálno-organické sedimenty: jemnopiesčité, ílovité až hnilokalové humózne hliny mŕtvych ramien a močiarov, holocén | fluviálne sedimenty: litofaciálne nečlenené nivné hliny, alebo piesčité až štrkovité hliny dolinných
The fishing district description states the bottom: fine-grained, muddy; the geological map shows something different, and the district description is more precise.
The map shows the bedrock geology, not the exact bottom at the spot. The actual bottom material may differ, especially where sediment has been deposited.
Aquatic insects
Aquatic insect swarming (iNaturalist)How many observations of mayflies, caddisflies and stoneflies people nearby recorded this month compared with the annual average. For fly anglers it hints at insect hatches.
Few insectsNovember: 0.0× the average month
Jan
Feb
Mar
Apr
May
June
July
Aug
Sep
Oct
Nov
Dec
Mayflies0Mayflies: dry fly on the surface, especially at dusk.
Caddisflies0Caddisflies: in the evening and at night by the bank; a nymph and a wet fly also work.
Stoneflies0Stoneflies: clean, cold streams, often already at the end of winter and in early spring.
0.0× the average month, 0 of 45 observations in the year, iNaturalist.
The observations are added by people from the surrounding area; they are not measurements at the water. They show when aquatic insects usually appear and are useful mainly for fly fishing.
Groundwater: measured values
Groundwater nearby (SHMÚ)Measured groundwater values from stations within 10 km of the fishing district (nitrates, harmful substances, ammonium, iron, chlorides) and the SHMÚ yearbooks.
A typical value from 8 groundwater stations within 10 km of the fishing district (nearest 0.4 km), measured in 2025. Closer stations carry more weight. This is groundwater near the district, not a measurement in the watercourse itself. The standard is the limit that SHMÚ gives for the indicator (for drinking water); a value equal to the standard counts as an exceedance, as it does at SHMÚ. The label "somewhere above the standard" means that the typical value is below the standard but at least one station exceeds it; which one is shown on the tile. Fish are more sensitive to some substances than people are.
Ammonium
0.25mg/l
close to the standard
Standard 0.5 mg/l. Range 0.005 to 0.47 mg/l, 8 stations.
Nitrites
0.02mg/l
far below the standard
Standard 0.5 mg/l. Range 0.005 to 0.05 mg/l, 8 stations.
Nitrates
1.9mg/l
above the standard somewhere
Standard 50 mg/l. Range 0.5 to 112 mg/l, 8 stations. Above the standard: 1 of 8 (Sered-dolna Streda, 1.3 km from the fishing district).
Oxygen
0.05mg/l
low oxygen
Mark on the dial: 9 mg/l, the guideline for salmonid waters. Range 0.01 to 0.11 mg/l, 8 stations.
Water temperature
12.1°C
warmer
Range 11.5 to 13.6 °C, 8 stations.
pH
7.27
suitable for fish
Range 7.11 to 7.35, 8 stations.
Water hardness
6.49mmol/l
hard
Range 4.89 to 8.13 mmol/l, 8 stations.
Iron
2.62mg/l
above the standard
Standard 0.2 mg/l. Range 0.002 to 4.15 mg/l, 8 stations. Above the standard: 6 of 8 (highest: Sered, 0.4 km from the fishing district).
Manganese
0.53mg/l
above the standard
Standard 0.05 mg/l. Range 0.12 to 0.83 mg/l, 8 stations. Above the standard: 8 of 8 (highest: Horne Saliby-dolna Luka, 0.8 km from the fishing district).
Chlorides
95.2mg/l
below the standard
Standard 250 mg/l. Range 41.3 to 205 mg/l, 8 stations.
Sulfates
243mg/l
close to the standard
Standard 250 mg/l. Range 89.5 to 357 mg/l, 8 stations. Above the standard: 3 of 8 (highest: Sered, 0.4 km from the fishing district).
Conductivity
117mS/m
close to the standard
Standard 125 mS/m. Range 94.4 to 150 mS/m, 8 stations. Above the standard: 3 of 8 (highest: Sered-dolna Streda, 1.3 km from the fishing district).
Metals and metalloids
85% of standard
close to the standard
Highest: Chromium 52 µg/l (104% of the standard, 1.3 km from the fishing district). 8 stations. Above the standard: 1 of 8.
Pesticides
20% of standard
below the standard
Highest: propisochlor 0.02 µg/l (20% of the standard, 0.6 km from the fishing district). 2 stations.
Solvents and benzene
0% of standard
not detected
Below the limit of quantification: substances from this group were not detected in the samples. 1 station.
PAHs (combustion, petroleum substances)
0% of standard
not detected
Below the limit of quantification: substances from this group were not detected in the samples. 1 station.
How it affects fish and the water
Ammonium
Ammonium ions are not very toxic in themselves, but depending on pH and temperature part of them turns into ammonia (NH₃), which damages the gills and stresses fish. The higher the pH and temperature, the more ammonia there is (Emerson et al. 1975). The repealed Directive 2006/44/EC gave a guideline of at most 0.04 mg/l of ammonium for salmonid waters and 0.2 mg/l for cyprinid waters.
Nitrites
Nitrites are toxic to fish: they pass through the gills into the blood and turn hemoglobin into methemoglobin, which does not carry oxygen, so fish "suffocate" even in oxygenated water. Salmonids are the most sensitive; chlorides in the water reduce the toxicity (Lewis and Morris 1986). Directive 2006/44/EC gave a guideline of 0.01 mg/l for salmonid waters.
Nitrates
Nitrates do not harm adult fish immediately, but they feed algae and plants and so contribute to over-fertilization and nighttime oxygen crashes. For sensitive aquatic animals (salmonids, amphibians, some invertebrates) Camargo et al. (2005) recommend keeping nitrates below 2 mg of nitrogen per liter, which is about 9 mg/l of nitrates.
Oxygen
Fish, especially salmonids, need a lot of oxygen. Directive 2006/44/EC gave a guideline of 9 mg/l for salmonid waters (in at least half of the measurements) and never less than 7 mg/l. Groundwater from deeper layers often has less of it; in the stream it is re-oxygenated only after it emerges.
Water temperature
Groundwater has an almost constant temperature throughout the year. Inflow from springs can therefore cool a stream in summer and warm it in winter, and such sections often serve as refuges for cold-water fish (Hayashi and Rosenberry 2002).
pH
Fish tolerate a pH of roughly 6 to 9 (Directive 2006/44/EC). Outside this range the gills are damaged and the toxicity of ammonia and metals changes.
Water hardness
Harder water (more calcium and magnesium) is better for fish: calcium protects the gills and reduces the toxicity of metals such as copper and zinc (Pagenkopf 1983), and keeps the pH stable. Soft water is more sensitive to metals and to acidification.
Iron
Iron is dissolved in groundwater at depth. When the water reaches the air, it oxidizes and precipitates as brown flocs that clog gills, cover gravel with eggs and invertebrates, and destroy shelters (Vuori 1995).
Manganese
Manganese is natural in deeper groundwater. For fish it tends to matter less than iron; the standard applies mainly because of the taste and color of drinking water.
Chlorides
Chlorides come from road salt, fertilizers and waste. The US EPA (1988) set 230 mg/l for long-term protection of aquatic life and 860 mg/l for short-term.
Sulfates
Sulfates are common in groundwater; they come from rocks (for example gypsum), fertilizers and mines. Together with chlorides they raise the mineralization of the water; the standard of 250 mg/l is set for drinking water.
Conductivity
Conductivity shows the total amount of dissolved salts. A higher value in groundwater is often natural (limestone, gypsum), but a sharp increase in a stream points to an inflow of salts from roads, mines or waste.
Metals and metalloids
Copper, zinc, nickel, cadmium and mercury are toxic to fish even at low concentrations, more so in soft water than in hard water (Pagenkopf 1983). The groundwater standard is set for drinking water, not for fish.
Pesticides
Pesticides get into groundwater from fields. The standard of 0.1 µg/l per substance (0.5 µg/l in total) is a drinking-water standard and is very strict; fish are usually harmed only by a much higher concentration. The value mainly shows how heavily the surroundings are burdened by agriculture.
Solvents and benzene
Chlorinated solvents (for example tetrachloroethene) and benzene come from industry, treatment plants and petrol stations. They are toxic and break down slowly in groundwater.
PAHs (combustion, petroleum substances)
PAHs are formed by combustion and petroleum spills. The standard for benzo(a)pyrene (0.01 µg/l) is very strict for drinking water because it is a carcinogen.
Sources
Camargo, J. A., Alonso, Á., Salamanca, A. (2005): Nitrate toxicity to aquatic animals: a review with new data for freshwater invertebrates. Chemosphere 58, 1255–1267.
Lewis, W. M., Morris, D. P. (1986): Toxicity of nitrite to fish: a review. Transactions of the American Fisheries Society 115, 183–195.
Emerson, K., Russo, R. C., Lund, R. E., Thurston, R. V. (1975): Aqueous ammonia equilibrium calculations: effect of pH and temperature. Journal of the Fisheries Research Board of Canada 32, 2379–2383.
Directive 2006/44/EC on the quality of fresh waters needing protection or improvement in order to support fish life (repealed in 2013; we give its values here only as an expert guideline).
Vuori, K.-M. (1995): Direct and indirect effects of iron on river ecosystems. Annales Zoologici Fennici 32, 317–329.
Pagenkopf, G. K. (1983): Gill surface interaction model for trace-metal toxicity to fishes: role of complexation, pH, and water hardness. Environmental Science & Technology 17, 342–347.
U.S. EPA (1988): Ambient Water Quality Criteria for Chloride. EPA 440/5-88-001.
Hayashi, M., Rosenberry, D. O. (2002): Effects of ground water exchange on the hydrology and ecology of surface water. Ground Water 40, 309–316.
Fish, wildlife, plants and hazards around the waterFish nearby (GBIF)Fish species that people have recorded around the water (GBIF database, recent decades). It is not a list of species in the fishing district, only a hint of what occurs in the area.Wildlife and hazards by the water (GBIF)Game animals, birds, plants and hazards (bear, ticks, mosquitoes, giant hogweed) that people have recorded around the water. It is not part of the fishing conditions score and is for information only.
Species that have been observed or recorded near the water. The number next to a fish is the number of records in the GBIF database, not the number of fish. Wildlife, plants and hazards do not enter the fishing conditions score; they are for information only. The species name leads to its page.
They breed in standing water, so they are worst around reservoirs, oxbow lakes and floodplain forests, especially at sunset.
How to protect yourself: When fishing in the evening and at night wear long sleeves, repellent and a net. Warmth and humidity after rain speed up mosquito development.
Transmits tick-borne encephalitis and Lyme disease. It waits in tall grass and in the vegetation along banks.
How to protect yourself: From spring to autumn check yourself after fishing, use repellent and tuck long trousers into your socks. Remove a tick as soon as possible with tweezers. A vaccination against encephalitis exists.
to be reckoned withinvasive speciesa single record
Most records: June.How to protect yourself
An invasive plant that grows along stream banks and on wet meadows. In sunlight its sap causes skin burns.
How to protect yourself: Do not touch it and do not walk through the vegetation. If the sap gets on your skin, wash it off with water and soap and protect the area from the sun. See a doctor for larger burns.
Large biting flies. They are most active on hot, windless days near water and on meadows.
How to protect yourself: They sting painfully, especially in summer around midday. Light-colored clothing with long sleeves and repellent help.
Fish: records since 1995 from the surroundings of the water (a rectangle around the fishing district). These are observations and collections, not a list of the fish in the fishing district, so a species may be missing even where it lives.
Invasive species (red label) displace native fish and occupy shallows. Catching and handling them is governed by the fishing regulations; check them before fishing.
Wildlife, plants and hazards: records come from observations and also reflect where observers move around; they are not density measurements or a guarantee of an encounter. They apply to the surroundings of about 35 × 55 km.
Bedrock, watercourse and springs on the map, values at the location of the water, geomagnetic activity and earthquakes. This is information about the environment; only small hypotheses marked with a confidence level (faults and rocks, geomagnetic storm) enter the score.
The bedrock map needs JavaScript to be turned on.
Geology
Geological map of Slovakia 1 : 50,000: rocks beneath the surface, from alluvial gravels and sands through clays to granites and limestones. Colors follow the ŠGÚDŠ legend; clicking the map shows a description of the rock at that spot.
For anglers: Gravel bars and rocky riffles give a clean bottom and habitat for zander, perch and barbel. Clayey and muddy ground holds food for carp and bream. Limestone and dolomite give harder water that is richer in food than granite and quartzite.
Radon risk
Radon risk of the bedrock (low, medium, high). It is based on the radioactivity of rocks and on fissures. The map shows the bedrock, not radon in water.
For anglers: Radon is a natural tracer of groundwater. Bedrock with a higher radon risk (granite, gneiss, tectonic faults) tends to be where fissure water comes to the surface. Most of Slovakia is "medium", so mainly a high risk is of interest.
low 36.7%
medium 63.0%
high 0.3%
Uranium (eU)
Equivalent uranium in surface rocks from airborne gamma spectrometry (ppm). From 4 ppm the bedrock is usually classified as having an elevated radon risk.
For anglers: A high uranium level is a sign of granite, gneiss and black shales, that is, rocks from which radon and dissolved substances get into the water. It has no direct meaning for bites, but it helps to read the geology of the area.
no data
0 – 1
1 – 2
2 – 3
3 – 4
4 – 5
5 – 7
7 – 35
Gamma radiation
Gamma radiation dose rate in air (nGy/h) from an airborne survey. It is the natural background of the bedrock, not pollution.
For anglers: Higher values are found in rocks rich in uranium, thorium and potassium (granite, gneiss, flysch with shales). It complements the uranium map; for an angler it mainly shows where the bedrock changes.
no data
0 – 20
20 – 40
40 – 60
60 – 80
80 – 100
100 – 140
140 – 180
180 – 220
220 – 999
Magnetics
Anomalies of the Earth's magnetic field (ΔT, in nT) caused by rocks with magnetic minerals, such as volcanic rocks, basalts or amphibolites.
For anglers: Fish (especially salmonids and eels) sense the magnetic field. Whether local anomalies affect their movement and bites has not been shown; it is treated as a hypothesis.
-1 217 – -1 000
-1 000 – -250
-250 – -200
-200 – -190
-190 – -180
-180 – -170
-170 – -160
-160 – -150
-150 – -140
-140 – -130
-130 – -120
-120 – -110
-110 – -100
-100 – -90
-90 – -80
-80 – -60
-60 – -40
-40 – -20
-20 – 0
0 – 10
10 – 20
20 – 30
30 – 40
40 – 50
50 – 70
70 – 100
100 – 150
150 – 200
200 – 250
250 – 300
300 – 400
400 – 500
500 – 600
600 – 700
700 – 800
800 – 900
900 – 1 000
1000 – 1 100
1100 – 1 130
Click or tap the map to find the value at that location.
Values at the water spotBedrock radon risk, uranium, thorium, potassium, gamma radiation and magnetic anomaly at a single spot by the water (marked with a dot on the map).
Bedrock radon risk
medium
Common for most of Slovakia.
low
medium
high
Uranium (eU)
2.5ppm
common
Typical background of the rocks.
Thorium (eTh)
6.9ppm
below the crustal average
Natural background of the rocks.
Potassium (K)
1.27%
below the crustal average
Natural background of the rocks.
Gamma radiation
48nGy/h
around the world average
Natural background of the bedrock.
Magnetic anomaly (ΔT)
139nT
above the average of the surroundings
Deviation of the magnetic field from the average of the surroundings.
below averageabove average
The values apply to a single spot (marked with a dot on the map), not as an average of the whole watercourse or river basin. Radon is a natural tracer in groundwater; the map does not include radon in water, only the bedrock risk.
Mark on the dial: the average of the upper continental crust (uranium 2.7 ppm, thorium 10.5 ppm, potassium 2.3%; Rudnick and Gao 2003) and the world average of the natural outdoor dose 59 nGy/h (UNSCEAR 2000). The needle does not swing towards “good” or “bad”; it only shows where the value lies.
Elevated uranium or radon is only information about the rock. It has no proven significance for bites; it helps to read what bedrock the water comes from.
Faults and springs
Faults and springsThe distance to the nearest tectonic fault on the geological map and the number of springs nearby. Fissure groundwater flows out along faults.
Nearest fault
up to 1 km
fault nearby
Tectonic fault on the geological map.
Springs and outflows
0
none marked
None within 1 km.
expected
Fissure groundwater flows out of the bedrock along faults and at springs. It tends to be cooler in summer and warmer in winter than the water in the stream, so according to anglers' experience fish stay near such places in extreme weather (summer and winter islands of a more suitable temperature).
However, fresh fissure water can have little oxygen. This is anglers' experience, not a phenomenon measured at this fishing district.
Faults are from the geological map at 1 : 50,000. Springs come from a hydrogeological map that covers only some regions, so zero does not mean there are no springs there.
Rocks and water chemistry
Rocks and water chemistryThe prevailing group of rocks at the water spot and what it usually means for the hardness, pH and richness of the water.
Bedrock at the water spot
Alluvium
The prevailing group of rocks according to the map.
Gravels, sands and loams in the valley tell about the valley floor, not about the rock in the catchment. The water chemistry is determined mainly by the bedrock higher up above the spot.
The rock at a single spot does not determine the chemistry of all the water: that depends on the bedrock across the whole catchment above the spot. The figure serves as a hint, not as a measurement.
Geomagnetic activity
Geomagnetic activity (Kp)The planetary Kp index (0 to 9) measures the fluctuation of the Earth's magnetic field. From 5 it counts as a geomagnetic storm. The last 48 hours and a forecast for 24 hours are shown.
Kp index
3.3from 9
quiet field
Latest measurement (7 Nov 2026 10:00). The dot on the dial is the highest forecast for the next 24 hours.
48 h agonow+24 h
Highest forecast Kp in the next 24 hours: 4.7 (unsettled field).
Kp (0 to 9) measures the fluctuation of the Earth's magnetic field caused by the solar wind. From 5 it counts as a geomagnetic storm. Fish, especially salmonids and eels, sense the magnetic field. That their bites depend on Kp has not been shown, though: these are anglers' observations and hypotheses.
The value is the same for the whole of Slovakia. It enters the activity score only during a strong geomagnetic storm (a hypothesis, −1 to −2 points).
Earthquakes nearby
Earthquakes nearbyTremors recorded within 150 km of the water in the last 30 days (GFZ GEOFON catalog).
Earthquakes nearby
0tremors
no tremors
Within 150 km over the last 30 days (from magnitude 1.0).
According to angling lore, fish (especially catfish and eels) react restlessly to tremors beforehand or stop biting. This is not reliably proven, and with weak tremors it is coincidence. People mostly do not notice deeper tremors from the Carpathians (for example near Komárno and Dobrá Voda) at all.
The GEOFON catalog is global; weak tremors near Slovakia may not all be in it. It is not counted in the activity score.
Sentinel-2 (optical) and Sentinel-1 (radar), updated roughly every 6 days
OvergrowthClean surface
IceNo ice
The watercourse is narrower than a satellite pixel (10 m). The values are therefore taken from a strip around the fishing district line and from pixels where water mixes with the bank, so they are only approximate and may also show the bank. The water surface area is not assessed for a watercourse, and estimates over the water appear in the image only where the watercourse is wider than a satellite pixel.
Surface overgrowthThe share of the fishing district's area where the satellite sees green vegetation (NDVI index above 0.3): floating and emergent plants and reeds at the bank.
0 % of areaClean surface
clean
partially
markedly
strongly
The share of the area with green vegetation (plants on and just below the surface, reeds at the bank).
Surface overgrowth trend: from 1 Sep 14:00 to 31 Oct 13:00. Latest 0%, lowest 0, highest 0%.
A strip of reeds at the banks may also be counted, so values on small areas may appear higher.
Sentinel-2, 31 Oct 2026, 99% of the area cloud-free
Ice on the surface
Ice on the surfaceThe share of the area where the satellite sees ice or snow. It cannot determine the thickness or load-bearing capacity of the ice.
0 % of areaNo ice
no ice
partially
mostly
whole
The share of the area where the satellite sees ice or snow. Over the last 20 days the highest was 0%.
The satellite cannot determine the thickness or load-bearing capacity of the ice. Never go onto the ice based on this figure.
Sentinel-2, 31 Oct 2026, 99% of the area cloud-free
Data have been stored since 27 Aug 2026 (13 periods of 5 days); the charts show how they develop. Download history (CSV)
Estimates from satellite images with a resolution of 10 to 20 m, not a measurement in the water. They are affected by clouds, shadows, wind and banks. Do not use them to decide about swimming or going onto the ice. Data: Contains modified Copernicus Sentinel data 2026, ESA, Copernicus Data Space Ecosystem. The procedure is described in the Methodology.
Historical images
Changes in the surroundings and nature from 2017 to 2023: how the banks, vegetation and landscape around the water change. The images switch automatically; you can also browse them by hand.
2017imaged 1 Aug 20172020imaged 20 Aug 20202023imaged 28 Sep 2023
2-0420-1-1Carp
2-0421-1-1Carp
2-0430-1-1Carp
2-0440-1-1Carp
2-0450-1-1Carp
2-0451-4-1Salmonid (trout)
Mayflies0Mayflies: dry fly on the surface, especially at dusk.
Caddisflies0Caddisflies: in the evening and at night by the bank; a nymph and a wet fly also work.
Stoneflies0Stoneflies: clean, cold streams, often already at the end of winter and in early spring.
Fish
Fish
Fish
Fish
Fish
Fish
Fish
Invasive species
Invasive species
Invasive species
Bird
Bird
Bird
Bird
Bird
Wildlife
Wildlife
Wildlife
Wildlife
Wildlife
Wildlife
Wildlife
Plant
Plant
Plant
Plant
Plant
Invasive plant
Risk
Risk
Risk
Risk
low 36.7%
medium 63.0%
high 0.3%
no data
0 – 1
1 – 2
2 – 3
3 – 4
4 – 5
5 – 7
7 – 35
40 – 60
140 – 180
180 – 220
220 – 999
-1 217 – -1 000
-1 000 – -250
-250 – -200
-200 – -190
-190 – -180
-180 – -170
-170 – -160
-160 – -150
-150 – -140
-140 – -130
-130 – -120
-120 – -110
-110 – -100
-100 – -90
-90 – -80
-80 – -60
-60 – -40
-40 – -20
-20 – 0
0 – 10
10 – 20
20 – 30
30 – 40
40 – 50
50 – 70
70 – 100
100 – 150
150 – 200
200 – 250
250 – 300
300 – 400
400 – 500
500 – 600
600 – 700
700 – 800
800 – 900
900 – 1 000
1000 – 1 100
1100 – 1 130
