Brook Trout
Brook Trout (Salvelinus fontinalis) is a freshwater species. The first thing to check: pale worm-like vermiculation — wavy light markings — across a dark green back and dorsal fin. The look-alike to rule out is Brown Trout: browns have dark spots on a light background, no vermiculation, and no white fin edging.
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| Scientific name | Salvelinus fontinalis |
|---|---|
| Also called | brookie, speckled trout, squaretail |
| Water | Freshwater |
| Group | Char |
| Temperature | The most cold-demanding common salmonid: optimal from 52 to 61 °F, stressed above 68 °F and dying above about 75 °F. |
How to identify a Brook Trout
- Pale worm-like vermiculation — wavy light markings — across a dark green back and dorsal fin.
- Red spots surrounded by blue halos on the flanks.
- White leading edges backed by a black line on the pectoral, pelvic and anal fins, and a squared tail.
If you would rather not work through a key on a wet deck, photograph the fish and let the app name it — you get the common and the scientific name back, and the record is filed before you release.
Fish it is mistaken for
| Species | How to tell them apart |
|---|---|
| Brown Trout | Browns have dark spots on a light background, no vermiculation, and no white fin edging. |
| Lake Trout | Lake trout have a deeply forked tail and pale spots on a dark ground, with no red spots or blue halos. |
Side-by-side comparisons
Read the full entry for Brown Trout and Lake Trout.
Where it lives
A char, not a true trout. Native to eastern North America's cold headwater streams, spring creeks and northern lakes, and widely stocked in western mountain water.
Temperature
The most cold-demanding common salmonid: optimal from 52 to 61 °F, stressed above 68 °F and dying above about 75 °F.
The conditions that matter
Brook trout are a water temperature story before anything else. In summer they stack at spring seeps and tributary mouths where cold water enters, and abandon reaches that warm past the high 60s. Logging water temperature against every catch identifies the thermal refuges on your stream more precisely than any map.
Global Fishing League records 18 weather and water readings against every catch automatically — tide stage, barometric pressure, water temperature, salinity, dissolved oxygen, chlorophyll, swell, current, moon phase and more, taken at your GPS position at the moment you log the fish. Over a season that turns a hunch about brook trout into a pattern you can read.
See every reading recorded with a catch, or the guides to what each reading means.
Size limits, bag limits and seasons
Size limits, bag limits, slot limits and seasons are set by your state wildlife agency — and for many offshore and migratory species by federal regulators — and on many waters they differ from the statewide rule. They also change between seasons. Check the current regulations for the exact water you are fishing before you keep a fish — we do not republish limits here, because a number that is a season out of date is worse than no number.
What the app does do is make your side of it accurate: every catch carries a length measured from the photograph, a GPS position and a timestamp, exportable if you ever need to show your work for a tournament or a record claim. It is also what a Global Fishing League entry is built from — a record that verifies itself, without publishing where you caught the fish.