The Banded Killifish (Fundulus diaphanus) is a small (to 130 mm) freshwater fish The color is variable with sex and season, but the fish is usually tan to green above, with white to yellow, below, with dusky olive-yellow fins and 10-20 greenish brown bars. Breeding males have bright bluish-green bars with a yellow throat and fins. Fundulus diaphanus (Banded Killifish) is native to Atlantic drainages from South Carolina to the Gaspe Peninsula, with a limited range on the west coast of Newfoundland, and the Great Lakes-St. Lawrence and upper Mississippi drainages. The Banded Killifish enters brackish water, and can tolerate salinities up to 70 PSU though it does not usually occur above 20 PSU. Banded Killifish inhabit shallow fresh and brackish waters over a wide range of temperatures (6 to 38 C) (. In the laboratory, they tolerate gradual transfer to 70 PSU (Griffith 1975), but do not occur above 20 PSU in the Chesapeake Bay, and may not be able to reproduce above 10 PSU. Their preferred habitats are the shallow margins of lakes, ponds and sluggish streams, often near dense vegetation. They often swim in schools, just below the surface. The food of Banded Killifish feed on insect larvae and microcrustaceans. The gut contents often contain plant material, but this may be consumed incidentally (Jenkins and Burkhead 1993). Banded Killifish are common baitfish and likely prey for larger fishes and fish-eating birds.
Banded Killifish were first collected in the Columbia River estuary about 35 km upriver of Astoria in 1971 (Misitano and Sims 1974). They are now established in the river from Portland to Astoria (Farr and Ward 1991; Sytsma et al. 2004; USGS Nonindigenous Aquatic Species Program 2018). They occur upstream at least as far as Oregon City. One fish was caught in the Smolt Counting Facility, at John Day Dam, in central Oregon in central Oregon (USGS Nonindigenous Aquatic Species Program 2018). Between 2004, and 2008, Banded Killifish. In the comprised 7 to 43% of the fish caught in seining surveys (Haskell and Tiffin 2011). The Banded Killifish was probably introduced with bait, or as a stray with stocked fishes. In the lower estuary, Fundulus diaphanus was common both in the tidal freshwater zone, and the estuarine mixing zone