The banded killifish (Fundulus diaphanus), is a North American species of temperate freshwater killifish belonging to the Fundulus genus of the Fundulidae family. The natural geographic range extends from Newfoundland to South Carolina, and west to Minnesota. It occupies the Great Lakes drainages. The Banded killifish is the only freshwater killifish found in the Northeastern United States, but can occasionally be found in brackish water.
Etymology of the name
The common name, "banded killifish", is commonly referring to the distinct black and white vertical bandings found along their sides. In addition to the name Fundulus, it is derived from the word Fundus, which means "bottom" and the word diaphanus means "transparent" in Greek.
Fundulus diaphanus, the Banded Killifish, is described to have an olive color on the dorsal and white coloring under the ventral. Their throat and fins are yellowish in color. In addition, there are 13-15 rays on a killifish's dorsal fin and 10-12 rays on the anal fin. Furthermore, the homocercal tail of a Banded Killifish is slightly convex or rounded. It also have a small pelvic fin along the abdominal. The body is slender and elongated with somewhat of a flat side and flattened head and small terminal mouth position for surface feeding. Banded Killifish also have a row of small sharp teeth lining their upper and lower jaw. It does not have a lateral line along the side but it does have 39 to 43 cycloid scales in the lateral series. The average size of a Banded Killifish range from 10–13 cm in length and weighs a few grams. Additionally, there are multiple vertical black and silver/white stripes along both sides of the Banded Killifish; similar to its cousin species the Western Banded Killifish Fundulus diaphanus menona. The numbers of bandings on the dorsal fin of a Banded Killifish are useful in determining the sex of this species. The females tend to grow larger in size than the male. They also have larger bandings on the sides and appear black in color. In contrast, the males have pale gray bandings that are close together.
Range and distribution
The Banded Killifish are widely distributed throughout Eastern North America, ranging from South Carolina to as far north as the Atlantic Provinces. They are also found in the eastern part of Montana to Minnesota and throughout the suitable habitats of the Great Lakes watershed of southern Ontario to Lake Superior. Due to biogeographically isolation and limitation of potential for range expansion, banded killifish species were assigned a status of Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC).
The adults range from 2–3 years in age. Banded Killifish are schooling fish, usually traveling in groups of 3-6 individuals while the juveniles travel in groups of 8-12 due to their smaller physical size. They are most often found in the shallow and quiet area of clear lakes, ponds, rivers, and estuaries with sandy gravel or muddy bottoms with lots of aquatic vegetation. The sand and gravel provides hatchling and juveniles with places to hide when threatened by predatory fish such as the Largemouth Bass Micropterus salmoides, Northern Pike Esox lucius, and Trout. Due to the physical size of the Banded Killifish, it does not travel into the deep end of a body of water where it is vulnerable to predation as well as the inability to swim fast currents. However, adult Banded Killifish have been observed to travel into deep bodies of water for feeding purposes. Banded Killifish often congregate near aquatic vegetations as it provides protection to them as well as a safe breeding habitat.
Banded Killifish have been observed to feed on all levels of the water column. The adults feed on a variety of items such as insects, nymphs, mollusks, turbellarians, and other small crustaceans. In contrast, the smaller individuals are limited to fewer items such as chironomid larvae, cladocerans, copepods, and midge larvae. Both young and adult Banded Killifish have been observed to feed mostly in the afternoon.
Reproduction and life cycle
In most fish species, the females tend to be larger than males. Similarly, female Banded Killifish tend to be larger when compare to the male. The average adult size ranges from 10–13 cm long and weight a few grams. Banded Killifish are commonly observed to spawn in dense aquatic vegetation because they practice external fertilization where the female lays her eggs equipped with adhesive threads that adhere to plants. They are also observed to spawn from June to mid-August in shallow waters. During the spawning season, the males go through a color change phase. They develop a bright blue patch near the anal fin. In addition, the lower portion of the body changes to a bright blue color. Spawning occurs at water temperatures of 21˚ C to 23˚ C. The male chooses a site in the shallow part of the water and protects it from other males. When a female appears, the male will court the female and fight with the other prospecting males. The female will emit one egg while the male pursues her. Once together, the female emits 10 eggs that falls onto the bottom or gets attached to aquatic plants in the chosen spawn area. The male will continue to pursue the female until the female have laid 50 to 100 eggs. A single female may lay several clutches of eggs during one summer. After the eggs have been fertilized, both the parents will leave and go their separate ways; the eggs do not receive parental care. 6-7 millimeter fries emerge within 10 to 12 days depending on the temperature of the water. They reach maturity at approximately 1 year with an average length of 6 cm. Banded Killifish can live for a little over 2 years. However, there have been some that have been observed to live up to 3 years.
Banded Killifish are euryhaline but they usually inhabit freshwater streams and lakes. The largest adult recorded was 12.8 cm and it was observed in Indian Bay, Canada. People have used Banded Killifish as fish bait. Most people do not favor them as pets because they take more care than the average person can provide. Therefore they do not survive well in an aquarium setting. They are important to aquatic ecosystems because they are a food source for larger fishes such as Largemouth Bass Micropterus salmoides, Northern Pike Esox lucius, and trout. They are also a food source for birds such as Belted Kingfisher Megaceryle alcyon, Mergansers Mergus merganser, and herons.
In January 2005, the Banded Killifish have been listed as a Vulnerable Species under the Newfoundland Labrador Endangered Species Act' and the Canada Species at Risk Act (SARA). This species is facing habitat degradation due to industrial development, motorized watercraft activities, and removal of aquatic vegetations.
- Page, Lawrence M. and Brooks M. Burr (1991), Freshwater Fishes, p. 216, Houghton Mifflin, New York. ISBN 0-395-91091-9
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