New York Science Journal 2015;8(11) http://www.sciencepub.net/newyork 83 Food and Feeding Ecology of Chrysichthys nigrodigitatus in the Cross River Estuary, South Eastern Nigeria Ubong Uwem George 1 , Edidiong Okokon Atakpa 2 1 Department of Zoology and Environmental Biology, University of Calabar, Cross River State, Nigeria. 2 Department of Zoology, University of Uyo, Akwa Ibom State, Nigeria. talk2georgeubong@gmail.com Abstract: Chrysichthys nigrodigitatus are important, highly valued and threatened brackish water species in the Cross River Estuary, Nigeria. Studies on the Food and Feeding Ecology of Chrysichthys nigrodigitatus in Cross River Estuary, was studied between July and September 2014 aimed at understanding the food and feeding ecology of C. nigrodigitatus. Food items in the gut of Chrysichthys nigrodigitatus were evaluated by occurrence and numerical abundance methods. The results on the food and feeding habits of C. nigrodigitatus in the Cross River Estuary revealed that the species feed mostly on food from animal origin, although diatoms and other plant materials were also identified. Food items isolated from the gut of the species included; Amphipods, crab/ crab particle, mud / sand particle, diatom, shrimps / shrimp parts, bivalve, mollusk, small fish, Copepods, fish bones, fish scales, prawns, crustacean and detritus which could not be determine empirically. The condition factor calculated for the species varied during the study period with a mean value of 1.38 in July, 1.44 in August and 1.57 in September. Based on the food items isolated from the gut of the C. nigrodigitatus, the species could be considered as a voracious Omnivore in the Cross River Estuary, while the variations in the condition factor of the species in the Estuarine system may indicate a period of high yield or otherwise of the species in the Cross River Estuary. [George, U. U., & Atakpa, E. O. Food and Feeding Ecology of Chrysichthys nigrodigitatus in the Cross River Estuary, South Eastern Nigeria. N Y Sci J 2015;8(11):83-90]. (ISSN: 1554-0200). http://www.sciencepub.net/newyork . 12. doi:10.7537/marsnys081115.12 . Key words: Food, Feeding Ecology, Chrysichthys nigrodigitatus, Cross River Estuary, Nigeria. 1.0 Introduction Chrysichthys nigrodigitatus with a common name silver cat fish is a demersal protomodromous species. It occurs in shallow waters of (less than 4m) and is confined to the mud and fine sand bottom. They are Omnivorous in nature feeding on varieties of food stuffs which include seeds, insects, bivalves and detritus (Reed et al., 1967). The richness and variety of various tropical aquatic habitats provide a wide range of possible food organisms for fishes. These originate either from within the aquatic ecosystem itself (autochthonous food sources) or from outside (allochthonous food sources). Feeding becomes specialized with age and size; large Chrysichthys nigrodigitatus may feed on decapods and fish (Laleye, 1995). It can grow to 50cm (18 inches) with temperature of 23 0 C – 26 0 C with pH 6.0-7.2. In Nigeria, C. nigrodigitatus is a highly valued food fish and is among the dominant fishes of commercial catches as well as culturable fish species from the wild (Ezenwa et al., 1986, 1990). C. nigrodigitatus has large eyes (large mouth and relatively small barbels on this species which usually relates to the habitat where it resides, being clear water where large barbels for feeling for food is not needed, hence the large eyes for hunting preys. The dorsal fin is preceded by a spine. Adipose fin is present and can have a relatively long base in some species. The pectoral fin can be serrated. The body is completely naked (they have no scale). The maximum length is about 1.5meters (4.9ft). Fishes of the Bagridae family have four pairs of well-developed barbels covered by a layer of taste bud epithelium (Zhang, et al., 2006). The colour is quite in this species, with a basic grey/silver body colouration and a white underside. It has a quite large dorsal fin and a deeply forked caudal fin. It is basically a food fish in its native Africa waters. Its flesh is reported to be quite good and they are fished using all types of capture methods including nets and weirs. The males when fully grown usually have a broader head which they use to dig out their breeding nests in their native habitats. Information from food studies can be used during species selection in fish culture. This is particularly useful in polyculture because proper selection of fishes with different feeding habits will prevent or significantly reduce competition during culture. Information on the biochemical composition and energy levels of the ingested food and its absorption in the alimentary canal provides base line data useful in artificial feed formulation for fish during their culture. For instance, a fish whose natural food is low in protein will likely not require a high protein feed during its culture. Such information can save the farmer a lot of money during feed formulation. Generally, the costs of producing adequate fed for