Mayflies
Stoneflies
Caddisflies
Damselflies & dragonflies
Gammarids
- Ecology: Moderate
- Chemical: Unknown
WFD classification · HRJKRN0269_001
Rules at a glance
- Permit required
Water temperature for Brown Trout
Ideal10°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour.
Likely species
Mayflies
Caddisflies
- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- Welshman's ButtonAlso possibleLower confidence#12–14 · Egg-layingSkitter it at dusk — this one's fished, not dead-drifted.
- CapererAlso possibleLower confidence#10–12 · AdultBig autumn sedge; fish dry at last light.
- Net-spinning caddisAlso possibleLower confidenceNearest relative#12–14–16 · PupaWidespread riffle net-spinner; evening emergence.
Damselflies & dragonflies
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 8 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 4 guilds as a supporter.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Top prey shown — see all 2 as a supporter.
Start free trial14-day free trial. Cancel anytime.
Evidence
Records-basedModerate confidence
Based on species-occurrence records, not local invertebrate surveys.
Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Small Dark OliveHatch
2
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Brown Trout
Top
6-10 · Pattern
High-confidence seasonal pick
Permits & access
Permit required — see local rules.
- Croatian fishing licence required
- Local concessionaire permit needed
- Zone A is fly-only catch-and-release; wider Gacka rules vary by zone, so fish the named zone rather than the river name alone.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Gacka Terrain map
Water quality (WFD)
The full read · show the working · for Brown Trout · confidence 90%
How the 87 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time85 × 13%11.1
Pressure80 × 7%5.6
Insect activity66 × 12%7.9
Conditions total= 87
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
- Trout 1 March → 31 October
- Grayling 15 May → 31 December
Gacka is an iconic Croatian spring-creek fishery — catch-and-release only for both grayling and brown trout along the entire river. Retention of grayling is prohibited. Fishing downstream of the zero bridge is allowed subject to concession rules. One rod, artificial fly or lure only. Check current concession holder rules — the Gacka is a conservation-priority water.
All grayling must be returned — retention is prohibited here.
Related guides
Booking & contacts
Gacka
Water temperature for Brown Trout
Ideal10°C est.ideal 10–16°C
0°14°28°
How to fish it · for Brown Trout
When
Nymphing can work through most of the day.
Where
Cover mixed depths.
Method
Start with tight-line nymphs and adjust if fish rise or drift higher.
Kit
9 ft #4 rod, floating line, 12 ft tapered leader to 4–5 lb fluoro tippet.
Why this works
Excellent — conditions well-balanced, with water temperature particularly in your favour.
Likely species
Mayflies
Caddisflies
- Green SedgeMost likelyLower confidenceNearest relative#10–12–14–16 · NymphFree-living green caddis larva; fast stony riffles.
- Welshman's ButtonAlso possibleLower confidence#12–14 · Egg-layingSkitter it at dusk — this one's fished, not dead-drifted.
- CapererAlso possibleLower confidence#10–12 · AdultBig autumn sedge; fish dry at last light.
- Net-spinning caddisAlso possibleLower confidenceNearest relative#12–14–16 · PupaWidespread riffle net-spinner; evening emergence.
Damselflies & dragonflies
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 8 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 4 guilds as a supporter.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Top prey shown — see all 2 as a supporter.
Start free trial14-day free trial. Cancel anytime.
Evidence
Records-basedModerate confidence
Based on species-occurrence records, not local invertebrate surveys.
Through the year
0–3 scale · September highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Small Dark OliveHatch
2
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Brown Trout
Top
6-10 · Pattern
High-confidence seasonal pick
Permits & access
Permit required — see local rules.
- Croatian fishing licence required
- Local concessionaire permit needed
- Zone A is fly-only catch-and-release; wider Gacka rules vary by zone, so fish the named zone rather than the river name alone.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Gacka Terrain map
Water quality (WFD)
- Ecology: Moderate
- Chemical: Unknown
WFD classification · HRJKRN0269_001
The full read · show the working · for Brown Trout · confidence 90%
How the 87 is built — score × weight = contribution
Temperature100 × 28%28.0
Flow80 × 22%17.6
Clarity95 × 18%17.1
Feeding Time85 × 13%11.1
Pressure80 × 7%5.6
Insect activity66 × 12%7.9
Conditions total= 87
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowon-river gaugeobserved
Prey activitymodelled from regional profilemodelled
Directions
Seasons & zones
- Trout 1 March → 31 October
- Grayling 15 May → 31 December
Gacka is an iconic Croatian spring-creek fishery — catch-and-release only for both grayling and brown trout along the entire river. Retention of grayling is prohibited. Fishing downstream of the zero bridge is allowed subject to concession rules. One rod, artificial fly or lure only. Check current concession holder rules — the Gacka is a conservation-priority water.
All grayling must be returned — retention is prohibited here.
Related guides
Booking & contacts