Banded killifish (Fundulus diaphanus)

GenusFundulus (1)
SizeMaximum length: up to 13 cm (2)

The banded killifish is classified as Least Concern (LC) on the IUCN Red List (1).

The banded killifish (Fundulus diaphanus) is a small, slender species of fish native to North America (2) (3) (4) (5). It has a small mouth (4) (5) (6), a lower jaw that protrudes further than the upper jaw (6), and an almost square-shaped tail (5).

The male banded killifish is olive-green on the sides, with a silvery-white belly and a contrasting darker area along the back (3) (4) (5) (7) (8) (9). As its name suggests, the banded killifish has a number of dark bands or bars running along the side (6) (3) (4) (5) (8). These bands are darker, narrower and shorter in the female banded killifish (3) (4) (7). The fins of this species are colourless to greenish (7).

There are currently two recognised subspecies of the banded killifish: the eastern banded killifish(Fundulus diaphanous diaphanous) is much larger than the western banded killifish (Fundulus diaphanous menona) (3) (9).

Native to North America, the banded killifish is found in both the United States and Canada. Its range extends along the eastern portion of the continent from Newfoundland in the north to South Carolina in the south (2) (3). The westward distribution of the banded killifish includes Manitoba in Canada, and Montana in the United States (3) (9).

While the banded killifish is tolerant of a range of salinities, it is usually found in freshwater habitats such as streams, rivers, ponds and lakes. This species shows a preference for shallow, clear and quiet water, with a sand, gravel or mud substrate. It is also often found near submerged aquatic vegetation (2) (3) (6).

The banded killifish prefers temperatures of between 10 and 25 degrees centigrade (2), but can survive much higher temperatures and also relatively low oxygen levels (9).

A gregarious species, the banded killifish is usually found in small shoals (2) (9). This species feeds throughout the water column (3) (6) (9), with its diet including a range of invertebrates such as fly larvae, small crustaceans, molluscs and flying insects (9) (6). It is also known to consume seeds of plants that have fallen into the water (4).

The banded killifish reaches maturity after around one year, and the breeding season varies with location, ranging from April to August (4) (6) (9) (10). This species is reported to spawn at temperatures between 19 and 23 degrees centigrade (9), and each male will establish and defend a territory (6) (10). During the breeding season, the male intensifies in colour, with the lower portion of the body taking on a brilliant iridescent bluish-green colouration (9) (10).

Spawning takes place among vegetation, where the female releases clusters of five to ten eggs. The egg clusters remain suspended below the female's abdomen via an adhesive thread until the male has fertilised them, after which they stick to the surrounding vegetation via individual threads, and remain there until hatching (9) (10).

The banded killifish is known to live for up to four years (9). 

While the banded killifish is not considered to be globally threatened, the Newfoundland population is currently recognised as a species of special concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (9). It is also listed as species of special concern under the federal Species at Risk Act (SARA) (11), and as a vulnerable species under the Newfoundland and Labrador Endangered Species Act (NL ESA) (12).

The Newfoundland population of the banded killifish is geographically isolated from other populations by 200 kilometres of ocean, and is prevented from dispersing to new habitat in the region by steep river gradients (9). Potential threats to this species in the area include habitat degradation due to logging, road development and mineral exploration (3) (9).

The banded killifish is currently protected by various legislation in Canada, all of which aim to prevent the decline and extinction of threatened species (3) (11) (12). The habitat of the banded killifish is protected in general by the federal Fisheries Act, which prohibits the destruction of fish habitat (13).

A management plan has been established for the banded killifish in Newfoundland, which aims to maintain the existing population levels and distribution of this species (3). Proposed conservation measures under the management plan include future monitoring and research, as well as raising public awareness of the banded killifish (3).

Find out more about the banded killifish:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. IUCN Red List (August, 2013)
  2. FishBase - Banded killifish (February, 2012)
  3. Fisheries and Oceans Canada (2011) Management Plan for the Banded Killifish (Fundulus diaphanus), Newfoundland. Fisheries and Oceans Canada, and Newfoundland and Labrador Department of Environment and Conservation. Available at:
  4. Forbes, S.A. and Richardson, R.E. (1920) The Fishes of Illinois. Authority of the State of Illinois, Illinois.
  5. Kraft, C.E., Carlson, D.M. and Carlson, M. (2006) Inland Fishes of New York (Online) Version 4.0. Department of Natural Resources, Cornell University, and the New York State Department of Environmental Conservation. Available at:
  6. Stewart, K.W. and Watkinson, D.A. (2004) The Freshwater Fishes of Manitoba. University of Manitoba Press, Winnipeg.
  7. Riehl, B. (1997) Aquarium Atlas. MERGUS - Verlag GmbH, Melle.
  8. Stauffer Jr, J.R., Boltz, J.M. and White, L.R. (1995) The Fishes of West Virginia. Academy of Natural Sciences of Philadelphia, Philadelphia.
  9. Chippett, J.D. (2003) Update COSEWIC status report on the banded killifish Fundulus diaphanus, Newfoundland population in Canada. In: COSEWIC assessment and update status report on the banded killifish Fundulus diaphanous in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa. Available at:
  10. Richardson, L.R. (1939) The spawning behaviour of Fundulus diaphanous. Copeia, 3: 165-167.
  11. Species at Risk Public Act (February, 2012)
  12. Newfoundland and Labrador Endangered Species Act (February, 2012)
  13. Fisheries Act (February, 2012)