Morphometric and Meristic Characteristics and Food Habits of the Knifefish in Lekki Lagoon, South Western Nigeria

Abstract

Morphometric and meristic characteristics, aspects of the food and feeding habits of Papyrocranus afer (knifefish) in Lekki Lagoon, South Western Nigeria were studied between January, 2010 and March, 2012. A total of 375 specimens, ranging from 10.9 – 63.1cm Standard Lengths (SL) and 23.1 – 1327.8 g Total Weights (TW) were collected monthly at landing sites of fishermen from the lagoon. The number of gill rakers in the species ranged from 6 – 10, dorsal fin rays 4 – 8, pectoral fin rays 4 - 15 and vertebrae 76 - 77. The Head Length (HL) ranged from 2.3 - 10.4 cm, Body Depth (BD) 2.4- 11.8 cm and Eye Diameter (ED) 0.9 - 1.8 cm. Proportion of HL: SL was 2.1 - 8.4, BD: SL 2.5 - 8.3; ED: HL ranged from 2.8 - 8.6. Papyrocranus afer was predatory in the lagoon feeding mainly on the prawn, Macrobrachium sp., accounting for about 15% and 12% of the food items by number and volume respectively and occurred in 12% of the stomachs with foods. Fish and gastropods were supplementary food items while insects and bivalves were minor foods. Pollution indicator species, Chironomus, were also part of food; this indicates that Lekki Lagoon may be polluted.

Key Words: Papyrocranus afer, biometrics, diets, Lekki Lagoon