Guide
Illustration· After a photo by Peter Pfeiffer (CC BY SA 4.0)Molluscs — snails
SuggestivePeak: Jun–Aug
What it is
Water snails are a minority food for most trout but the defining food for one Irish fish: the gillaroo of Lough Melvin, which feeds almost exclusively on bottom-living snails, sedge larvae and freshwater shrimp.
Life cycle
Juvenile snail
Small, bottom-dwelling stage, taken alongside adults.
Adult snail
Larger, hard-shelled — the gillaroo has evolved a thickened, muscular, gizzard-like stomach specifically to grind these shells, a genuinely unusual adaptation among salmonids.
In Ireland
The catalogue's answer is the Black & Peacock Spider, explicitly tagged snail and static, fished motionless close to bottom or weed. The "occasional snail rise" is real, but it is a static-presentation tactic, not a hatch.
Flies that imitate this
Where it matters
Sources & how we know this (1)
- Gillaroo snail diet, gizzard adaptation, Lough Melvin endemism
Wikipedia, Gillaroo · 2026-07-09
Draft reference — pending review.