Gag Grouper
Gag Grouper (Mycteroperca microlepis) is a saltwater species. The first thing to check: grey to brown-grey with dark worm-like or kiss-shaped markings on the flank, faint on large fish. The look-alike to rule out is Black Grouper: black grouper carry rectangular, more organised chain-link markings and a square-cut tail margin without the wavy white line.
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| Scientific name | Mycteroperca microlepis |
|---|---|
| Also called | gag, grey grouper, charcoal belly |
| Water | Saltwater |
| Group | Grouper |
| Temperature | Found between about 60 and 80 °F, moving shallower in the cool months and deeper in summer. |
How to identify a Gag Grouper
- Grey to brown-grey with dark worm-like or kiss-shaped markings on the flank, faint on large fish.
- The tail fin has a wavy, dark-edged rear margin with a distinct white line just inside it.
- The spiny dorsal edge is notched between spines, unlike a red grouper's straight edge.
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 |
|---|---|
| Black Grouper | Black grouper carry rectangular, more organised chain-link markings and a square-cut tail margin without the wavy white line. |
| Red Grouper | Red grouper are rusty red with a straight-topped spiny dorsal and a squared tail. |
Side-by-side comparisons
Read the full entry for Black Grouper and Red Grouper.
Where it lives
Gulf of Mexico and the south Atlantic. Adults hold on offshore ledges, wrecks and reef; juveniles use inshore grass flats and estuaries. Moves shallower as water cools in autumn.
Temperature
Found between about 60 and 80 °F, moving shallower in the cool months and deeper in summer.
The conditions that matter
The autumn move of gag onto shallower nearshore structure is driven by falling water temperature, and it is one of the most predictable seasonal shifts in Gulf fishing. Water temperature and depth logged per catch turn that from folklore into a date range you can plan around.
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 gag grouper 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.