Aspects of the Biology of Chrysichthys nigrodigitatus in Uta-Ewa Creek, Akwa Ibom State, Nigeria

Abstract

The aspects of the biology of silver catfish, Chrysichthys nigrodigitatus was investigated from July to September 2017 in Uta Ewa Creek, Akwa Ibom State, Nigeria. A total of 90 fish samples were collected from artisanal fisher folks at the landing site. Fish sizes ranged from 12.20cm to 22.90cm standard length, 16.70cm to 31.90cm total length and 30.30g to 178.60g body weight. Monthly condition factor of 1.77, 1.765 and 1.68 were recorded in July, August and September respectively. The mean value of 1.74 showed a negative allometric growth pattern. This implied that fish lengths were not in proportion with weights. The length-weight linear relationship was InW ═ -3.4164 + 2.7545x with a correlation value of 0.8236. The results of stomach content analyses revealed that the fish fed on various food items consisting of phytoplankton 56 (62.22%), crustaceans 8 (8.88%), insects 10 (11.11%), molluscs 7 (7.77%), worms 4 (4.44%) and unidentified materials 5 (5.55%). The most abundant food items found at the study site throughout the period of sampling was phytoplankton (59%), insects (11%), crayfish (9%), periwinkle (7%), worms (4%), crabs (4%) and unidentified food items (6%). From the results of this study C. nigrodigitatus could be considered as being omnivorous.

Key Words: Condition factor, Chrysichthys nigrodigitatus, diet, length-weight relationships, selection factor, Uta Ewa Creek