Habitat Type: Freshwater
Comments: River channels, margins, backwaters; springs, marshes, and artificial habitats of all kinds (Minckley et al. 1991). Often in shallow, often stagnant, ponds and the shallow edges of lakes and streams where predatory fishes are largely absent and temperatures are high. Most abundant in shallow water with thick vegetation (Hubbs 1971). Also in brackish sloughs and coastal saltwater habitats (Tabb and Manning 1961, Odum 1971). More tolerant of pollution than most other fishes (Lewis 1970, Kushlan 1974). Tolerates dissolved oxygen levels as low as 0.18 mg/L (Ahuja 1964). Cannot tolerate extreme cold; temperature apparently limits range northward (Hubbs 1971). However, some populations are known to overwinter under ice in Indiana and Illinois (Krumholz 1944).