Aspects of the biology of the characid Anoldichthys spilopterus Boulenger (Osteichthyes: Characidae) in the River Jamieson, Delta State, Nigeria

Abstract

Data on the abundance, distribution, growth, dietary patterns and reproduction of the characid Anoldichthys spilopterus in the River Jamieson, Nigeria, are presented. A spilopterus constituted 13.8% of the characid catch and was captured throughout the year with peak abundance during the dry season. It attained a maximum standard length of 9.0 cm and weighed of 18.5g. The growth in length relative to weight was allometric. The condition factor ranged from 2.01 - 2.76 and was generally inversely related to increase in fish length. The condition factors were higher during the wet season than in the dry season. A. spilopterus was a mesopredator feeding essentially on a variety of allochtonous insects, with fish, plant seeds and detritus supplementary to the diet. It was primarily a day feeder with no clear qualitative variation in feeding habit with size. A. spilopterus is a one-time spawner, breeding between June and September. Fecundity estimates ranged from 100 to 380. Average GSI value was 1.83%.


KEY WORDS: Anoldichthys spilopterus, characid, abundance, distribution, food, feeding habit, growth pattern, breeding, Nigeria.


Tropical Freshwater Biology 10 (2001) 57 – 74