Diet composition and feeding inter-relationship in the claroteid catfish Clarotes laticeps in the lower river Niger

Abstract

Food and feeding interrelationship was investigated in samples of Clarotes laticeps collected from the lower River Niger between January 2010 and December 2012. Fish guts were analysed to determine diet composition using a combination of methods; frequency of occurrence (%FO), Numerical composition (%N) and total wet weight( %W) of food items per food categories. The relative importance of each of the different dietary items in the fish gut was evaluated using the index of relative importance (%IRI). Diet breadth and overlap were deduced using Levin’s Standardized Index and simplified Morsita’s Index , respectively. Fish accounted for 50.2% of the total weight of food items (%W) found in the fish stomach. It occurred in 37.5% of the stomachs containing food (%FO) and accounted for 32.0% of the total dietary items enumerated (%N). Crustaceans constituted 26.0% by weight (%W), 49.8% by frequency of occurrence (%FO) and 25.2% by numerical composition (%N). The index of relative importance (%IRI) was 58.41% for crustaceans and 22.58% for fish. Other important dietary constituents (%IRI) included mollusks (6.09%), tadpoles and adult frogs (3.25%), annelids (1.13) and plant seeds (1.53%). Similarity of diet was found to be more between medium and bigger samples than between juvenile and adult fish.

Key Words: Clarotes laticeps, diet composition, feeding, inter-relationship, River Niger.