Young warmouth sun fishes are most likely to eat small insects and zooplankton, and move towards larger prey as they get older. (Flemer) Adult warmouths will typically eat small crustaceans, other small fish, and insects.

Feeding Habits

The warmouths spend much of their time residing in heavily vegetated areas, where they lie in wait for their prey, ready for the ambush. These fish are largely nocturnal feeders that spend much of the day digesting their catch from the previous night.

How they obtain nutrition

The warmouth has a simple digestion system consisting of a single tubular tract which travels the length of the fish and ends in the anus. (Sadizikowski) The warmouth has a closed circulatory system, meaning its blood is transferred to its tissues by arteries moving out and away from the heart to the tissues. (Sadizikowski)