The mud sunfish is a small fish which can be distinguished from other members of its family by its possession of 5 or more spines in its anal fin, by having less than 15 gill rakers and in being the only species in its family which has cycloid scales. Its body is oblong and compressed with a large mouth and eyes. This species has rounded pectoral and caudal fins. which are clear through to dark olive in color and the anal fin has a black margin. It has a dark spot on the gill cover and the color of its body varies from brown on the back to yellowish tan on the flanks, while the juveniles are pale olive. There are 3-4 parallel dusky, horizontal stripes which extend from the cheek along the body. They can grow to a maximum total length of, although is a more common total length.
The mud sunfish is found in freshwaters which are stained dark with tannins. It has been recorded in slow-moving sluggish, well vegetated creeks, rivers, ponds, lakes and swamps. As its common name suggests it prefers substrates consisting of mud or detritus. This is a nocturnal species which lives at naturally low densities and as a result there have been few studies conducted on it. What has been discovered is that spawning appears to vary with latitude with gravid females being collected during the late spring and early summer in Delaware while further south, in North Carolina and Georgia spawning takes place during the early fall and late winter. They have a maximum life span of 8 years and sexual maturity is attained at one year old. Their diet is made up largely of invertebrates including amphipods, decapods, and beetles with some smaller fishes and Odonata.
Conservation
The IUCN has assessed the status of the mud sunfish as Least Concern and states that its population is stable. In individual states, however, there have been significant reductions in the species range. In New York the species was only recorded from the Hackensack River and it has not been collected from there since 1935. Its range has also significantly reduced in New Jersey, particularly in the northern and central parts of the state but it remains reasonable common and widespread in the Pinelands. In New Jesrey the fish's decline is possibly a result of a number of reasons including land use and habitat changes and the introduction of non-native fish which predate on the mud sunfish and in this state it has been recommended that it be classified as a species of special concern. It has been extirpated from Pennsylvania.
