The Parasitic helminth fauna of Parachanna obscura from Lekki Lagoon, Lagos, Nigeria

Parachanna obscura, the African snakehead fish, were randomly selected and subjected to parasitologic investigations. A total of three hundred and forty specimens were monthly obtained over a period of one year. Helminth infections was observed to have a prevalence of 5.9% which accounts for twenty of the specimens to be infected with gastrointestinal helminth parasites. Parachanna obscura harboured two nematodes, Procamallanus sp (Spirocamallanus) and Contracaecum sp and a trematode, Clinostomum metacercaria. A sum total of twenty two helminthes was recovered from the fish. The male specimens (229) recorded a lower rate of infection (5.2%) than the females (111) which recorded a prevalence of 7.2%. The overall worm burden were low and independent of sex and size of the fish. [Researcher. 2010;2(9):78-84]. (ISSN: 1553-9865). Introduction Parachanna obscura (Gunther, 1861) the African snakehead fish species is common in Nigeria and several West African countries. The species has a native range from White Nile specifically the Jebel and Ghazal systems of Sudan (Bailey, 1994), Gambela region of Ethiopia (Golubtsov et al. (1995), Lake Chad basin, Zaire (Congo), Senegal River basins (Boulenger, 1907, 1916, Irvine 1947; Teugels and Daget, 1984; Bonou and Teugels, 1985; Skelton, 1988). The species was also recorded in Stanley Pool, Lualaba (Congo) River by Boeseman (1957). Dankwa, et al. (1999) reported that the fish is widely distributed in Ghana and can be both useful as food and aquarium species. Parachanna obscura has been reported to have a preference for marginal vegetation and floodplain habitat in the Sudan,( Bailey 1994), and occupies a wide variety of habitats including streams, rivers, lakes, lagoons and marshes (Bonou and Teugels (1985). In flowing water, the species occupies calm areas. The species has also been indicated to be ‘widely distributed’ in marshy habitats and can also be found in bank vegetation of river channels (Lowe-McConnell, 1988). Teugels et al (1992) also listed the species as common in stagnant side channels of the Cross River, Cameroon, Nigeria, and can be found among water logged fallen trees and leaf debris. The fish is in equatorial Africa which indicate it to be a strictly tropical species. The fish has generally been classified as carnivorous predators. Bonou and Teugels (1985) reported that the fish species is being used to control the young Tilapias in aquaculture ponds. Blache (1964) also recorded the food of young Parachanna obscura as Copepods and insect larvae. Adults of the fish prey on other fishes as reported by Copley (1952), Poll (157); Gosse (1963) and Teugels (1992). Adebisi (1981) reported that the juveniles of Parachanna obscura fed on prawn, copepods and aquatic insect larvae whereas adults fed only on fishes in Southern Nigeria. Victor and Akpocha (1992) also reported that in monoculture in a Nigerian pond, young of this species fed primarily on detritus and larval insects, whereas larger individuals contained fish parts and juveniles with insects and fish making up the bulk of the diet. The species has a distinct coloration among African Snakehead in having a series of dark blotches. The fish species does not also has Chevron shaped bars across the middle of the back. The fish has scales present in the jugular region, no canine teeth, head is depressed anteriorly, and is relatively long and covered with large scales. The fish is being cultured in Ghana (Morrice, 1991), Nigeria (Ajana, 1983; Ogbulie et al 2003); Victor and Akpocha, 1992), and Bnin (Jackson, 1988). The fish species has also been recommended for culture in the Central African Republic (Micha, 1974). It is also reported that little was known of the reproductive biology of Parachanna obscura Bonoun and Teugels (1985). Gosse (1963) stated that the young of Parachanna obscura are guarded by a large adult. In the Eastern part of Nigeria, a number of gastrointestinal helminth worms have been documented by Ogbulie et al. (2003). They reported the occurrence of Camallanus species, Capillaria species, Acetodoxtra species, Clinostomum species,