Freshwater Flounder: An Unusual Bottom-Dwelling Oddball

Freshwater flounder are among the more unusual oddballs in the hobby, instantly recognizable by their flattened, asymmetrical body with both eyes on one side.

Tank Setup

A soft sand substrate is essential, since flounder spend much of their time partially buried, using camouflage to ambush passing prey.

Water Requirements

Many freshwater flounder actually tolerate or require some brackish salinity, so research the specific species’ needs rather than assuming standard freshwater parameters apply.

Diet

Flounder are ambush predators and typically need live or frozen meaty foods, sometimes taking time to recognize non-moving prepared foods as edible.

Compatibility

Flounder are generally peaceful toward similarly-sized tankmates but will eat small fish or shrimp that fit in their mouths, so plan tankmates accordingly.

This is a specialized species best suited to experienced keepers — browse our broader freshwater fish selection for more beginner-friendly options if you’re just starting out.