Animal Diversity Web

Geographic Range

Hepsetus odoe is widespread in the tropical regions west and central Africa. It is found in most rivers in West Africa from the Senegal southwards to Botswana. The southern limit of its distribution is the Okavango Delta in Northern Botswana (Merron et al., 1990).

• Biogeographic Regions
• ethiopian
  • native

Habitat

Hepsetus odoe is usually found near the banks of rivers in heavy vegetation, but also can be found in swampy environments, lagoons and backwaters. In areas where one of its major predators is absent (Hydrocynus forskahlii), Kafue pike will venture into more open waters (Jackson, 1961).

• Habitat Regions
• tropical
• freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams

• Wetlands
• swamp

Physical Description

Hepsetus odoe bears a striking resemblance to the European pike. It is, however, the only member of its genus and a characiform, only distantly related to the European pike. Kafue pike are torpedo-shaped, predatory fish. The body form is elongate with a pronounced snout. The dorsal surface is usually dark brown or green while the ventral surface is silvery. The face is often light green or brown with prominent dark brown or black stripes radiating from the eye. The coloration of the adults is relatively uniform but coloration of young is extremely variable (Jubb, 1961).

The scales of the Kafue pike are rough to the touch and number 49-58 along its lateral line. The dorsal fin has 9 rays total, with 2 unbranched and 7 branched. The dorsal fin origin is set far back on the body, behind the anal fin origin. The adipose fin, with its red or orange base and black tip, lies midway between dorsal and caudal fins. The anal fin has a total of 11 rays with 2 unbranched and 9 branched. The unpaired fins often have fine black spots between the rays (Jubb, 1967).

The most striking feature of H. odoe is its dentition. Both upper and lower jaws are filled with sharp pointed teeth, but the lower jaw has two rows while the upper only has one. There are also two large canines in each jaw. Two pairs of dermal flaps can be found on the upper and lower jaws (Barnard, 1971). The folds on the upper jaw are smaller than those on the lower jaw. They were once thought to be sensory organs but are now thought to be used in building nests for breeding (Merron et al., 1990). (Barnard, 1947; Jubb and Manning, 1961; Jubb, 1967; Merron, et al., 1990)

• Other Physical Features
• ectothermic
• heterothermic
• bilateral symmetry

• Sexual Dimorphism
• sexes alike

• Average mass

  1.2 kg

  2.64 lb

• Average mass

  2200 g

  77.53 oz

  AnAge

• Range length

  37-47 (high) cm

  in

Development

Very little is known about the development of H. odoe. However, it is suspected that the species undergoes direct development due to a very short larval period (Merron et al., 1990). When the young hatch, they wiggle their way through the nest to the water. Upon submersion the larvae attach themselves to the bottom edge of the nest using a special cement gland on the top of their heads. They hang there, suspended tail down for four days. As they develop, they begin to move away from the nest, often attaching to nearby vegetation. As they become more developed, the fry rely less on their cement gland and eventually, in just a week or so, become free swimming.

Reproduction

The onset of the spawning season varies depending upon the region, but the method is consistant across Hepsetus odoe populations. Spawning season usually begins after the flood season has begun; it is suspected that flood waters may actually stimulate the gonads of H. odoe. However, water temperatures play a critical role as well, and it is not until August that the water temperatures are likely to reach optimal levels for the eggs and developing embryos.

Females are repeat spawners and produce about 6,440 eggs in a season. These eggs vary in size from 2.5-2.9 mm in diameter. As with many other species of fish, H. odoe must reach a certain length before being able to breed. Males mature at 140 mm while females do not mature until they reach 160 mm. Prior to spawning, the adults stake out a territory and begin defending it from rivals. They also begin to build a portion of a nest out of foam bubbles. The nest is irregularly dome-shaped with an average diameter of 17 cm and an average height of 9 cm. This nest will hold the fertilized eggs and will be guarded by the adults until after the eggs hatch. The fertilized eggs are inserted in the nest during spawning and actually rest above the surface of the water, often as much as 3 cm. The nest is built around strands of vegetation, which gives it extra stability and protection from wind induced wave action. The nest building is thought to give this species a few advantages in an area where actual flood levels and times fluctuate from year to year. 1) acts as a deterrent to predators due to both its placement in highly vegetation areas, as well as providing a hiding place for developing embryos and newly hatched larvae. 2) places the eggs out of the water and the embryos at the air/water interphase, the young are provided with an oxygen rich environment during a seasonal time of low oxygen concentration. 3) floats on the surface of the water, which keeps the nest at the optimal oxygen level when water levels fluctuate. 4) provides an anchor for the young to attach themselves to. This prevents the small fry from being swept away by the current into areas where they could be preyed upon or where there is insufficient oxygen for their development (Merron et al., 1990).

• Key Reproductive Features
• iteroparous
• seasonal breeding
• sexual
• fertilization
  • external
• viviparous

• Breeding season

  Spawning usually begins in August and continues until January. Although in some locations there is an extended spawning season which lasts until May.

• Average number of offspring

  6,440

The adults guard the foam bubble nests until the young have hatched and attached themselves to the bottom edge. During this time, it is believed that the adults actively protect and rebuild the nest, applying foam where needed. After the young have attached themselves to the bottom edge of the nest, the adults abandon it and their young. The nest breaks up about four days afterwards (Merron et al., 1990).

• Parental Investment
• male parental care
• female parental care

Lifespan/Longevity

Hepsetus odoe are known to live 4-5 years in the wild (Montambault, 2000). (Montambault, 2000)

• Average lifespan
  Status: wild

  4.5 years

• Average lifespan
  Status: captivity

  5 years

  AnAge

Behavior

• Key Behaviors
• natatorial
• motile

Communication and Perception

• Perception Channels
• tactile
• chemical

Food Habits

H. odoe is piscivorous, feeding on several species of smaller fish. They are primarily diurnal ambush predators, hiding out in dense vegetation and lunging suddenly to seize prey (Winemiller, 1993). Their diet consists primarily of cichlids and mormyrids. Although smaller specimens have been found to eat mochokid catfishes in greater amounts than cichlids or mormyrids (Winemiller, 1993).

• Primary Diet
• carnivore
  • piscivore

• Animal Foods
• fish

Predation

H. odoe avoids open water where its biggest predator is found. It uses weeds and vegetation along with its coloring to avoid detection (Jackson, 1961).

• Known Predators

  • tigerfish (Hydrocynus forskahlii)

Ecosystem Roles

Very little is known about the ecosystem role of this species, other than it is a high level predator in freshwater systems (Winemiller, 1993).

Economic Importance for Humans: Positive

H. odoe is a prized game fish in Africa. Anglers from all around the world come to fish for it. Despite its small size, the Kafue pike is considered a better sport fish than H. forskahlii (Sepupa, 1997).

• Positive Impacts
• food

Conservation Status

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  No special status

Other Comments

H. odoe is the only characid in its range that displays nest building reproductive behavior (Merron, Holden, & Bruton, 1990).

Contributors

William Fink (editor), University of Michigan-Ann Arbor.

Bobbie Stewart (author), University of Michigan-Ann Arbor.

References

Alphonse, A., R. Van Thielen. 1995. Ecology and fish catches of the Africa pike *Hepsetus odoe* in Lake Kariba, Zimbabwe. Environmental Biology of Fishes, 43(4): 381-391.

Barnard, K. 1947. A Pictoral Guide to South African Fishes. Capetown: Maskew Miller limited.

Bell-cross, G., J. Minshull. 1988. The Fishes of the Zimbabwe. Zimbabwe: The Trustees of the National Museums and Monuments of Zimbabwe.

Irving, F. 1947. The Fish and Fisheries of the Gold Coast. London: Government of the Gold Coast by the Crown Agents for the Colonies.

Jackson, P. 1961. Fishes of the Northern Rhodesia. Lusaka: The Government Printer.

Jubb, R. 1967. Freshwater Fishes of South Africa. Capetown: Gothic Printing Company.

Jubb, R., S. Manning. 1961. Freshwater fishes of the Zambezi River, Lake Kariba, Pungwe, Sabi, Zund and Limpopo. Capetown: Gothic Printing Company.

Merron, G., M. Bruton. 1995. Community ecology and conservation of the fishes of the Okavango Delta, Botswana. Environmental Bioloy of Fishes, 43(2): 109-119.

Merron, G., K. Holden, M. Bruton. 1990. The reproductive biology and early development of the African pike *Hepsetus odoe* in the Okavango Delta Botswana. Enviornmental Biology of Fishes, 28(1-4): 225-236.

Montambault, J. 2000. "Expediton Okavango Aquatic rapid assessment program in Botswana's Okavango Delta" (On-line). Accessed October 20, 2002 at http://animaldiversity.ummz.umich.edu/work/account/edit/um_bio440_02/77c365d023e22d51399b7cc49217f3e8?now=1037239276.5059#narrative2001/references/item:12.

Petr, T. 1974. Distribution, abundance and food of commercial fish in the Black Volta and Volta Man-made lake in Ghana during the filling period (1964-1968). Hydrobiologia, 45(2-3): 303-337.

Sepupa, 1997. "Toothy Critters African pike in the Okavango swamps" (On-line). Accessed Oct 23, 2002 at http://animaldiversity.ummz.umich.edu/work/account/edit/um_bio440_02/77c365d023e22d51399b7cc49217f3e8?now=1037239060.78706#narrative2001/references/item:11.

Winemiller, K., L. Kelso-Winemiller. 1994. Comparative ecology of the African pike, *Hepsetus odoe*, and tigerfish, *Hydrocynus forskahlii*, in the Zambezi River floodplain. Journal of Fish Biology, 45: 211-225.