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Species · Lookalikes

Bigmouth SleeperorFat Sleeper

Two fish anglers mix up. Here is what separates them, and what each one’s rules are in your state.

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Bigmouth SleeperGobiomorus dormitor
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Fat SleeperDormitator maculatus

Rules for both fish from 0 state rulebooks, checked Sep 14, 2026. Every rule names its source and the day it was last checked; the official rulebook is the final word.

How to tell them apart

Bigmouth Sleeper

Elongate, olive-brown sleeper to 2 ft with a huge mouth and separated dorsal fins; freshwater and brackish rivers.

Bigmouth sleeper, next to fat sleeper: larger, elongated, huge mouth.

Fat Sleeper

Stout, dark goby-like fish with a rounded tail and a wide head; brackish ditches and mangrove edges.

Fat sleeper, next to bigmouth sleeper: shorter, rounder.

Side by side

Bigmouth SleeperFat Sleeper
Scientific nameGobiomorus dormitorDormitator maculatus
Also calledGuavinaSleeper
WatersInshoreInshore
Heaviest state record
On the tableEdible in the Caribbean.Not eaten.
Rules of its own in0 states0 states

Rules for

Every state, both fish

StateBigmouth Sleeper: size · bag · seasonFat Sleeper: size · bag · season

In the app

Point the camera at the fish and Chum names it before you take the picture, bigmouth sleeper or fat sleeper, with the right rules for the water you’re standing in. No signal needed.

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Questions anglers ask

How do you tell bigmouth sleeper from fat sleeper?

Bigmouth Sleeper: Elongate, olive-brown sleeper to 2 ft with a huge mouth and separated dorsal fins; freshwater and brackish rivers. Fat Sleeper: Stout, dark goby-like fish with a rounded tail and a wide head; brackish ditches and mangrove edges. Fat sleeper, next to bigmouth sleeper: shorter, rounder. Bigmouth sleeper, next to fat sleeper: larger, elongated, huge mouth.

Which is better to eat, bigmouth sleeper or fat sleeper?

Bigmouth Sleeper: Edible in the Caribbean. Fat Sleeper: Not eaten.