Feeding Habits, Length-weight Relationship and Condition Factor of Spotted Tilapia (Tilapia mariae; Boulenger, 1899) (Pisces: Cichlidae) in the Adofi River, Niger Delta, Nigeria

Abstract

The food and feeding habits of fish have long attracted considerable attention from researchers, as they constitute a fundamental basis for the development and implementation of effective fisheries management programmes in both capture and culture fisheries. A comprehensive understanding of feeding ecology provides valuable insights into trophic interactions, resource utilisation, growth performance and habitat requirements, thereby facilitating the sustainable exploitation, conservation and management of fish populations. Cichlids are a dominant fish family in the Adofi River, and Tilapia mariae forms a significant component of local diets. The present study aimed to provide information on the food, feeding habits and growth characteristics of T. mariae from a stretch of the Adofi River, Niger Delta, Nigeria. The natural food of the species was studied from the stomach contents of 250 fish samples measuring 5.1-17.5 cm standard length and weighing 18.7-229.4 g. Stomach contents were analysed using the frequency of occurrence, numerical, fullness and point methods. Green algae, diatoms and desmids were the main food items of plant origin. Filamentous algae were the most preferred food items of plant origin, occurring in more than 90.0% of the fish examined. Coleoptera, diptera, trichoptera and chironomid larvae were the food items of animal origin. Feeding intensity varied seasonally, with peaks during the wet season. Tilapia mariae in the Adofi River was a daytime feeder, as the number of stomachs containing food items was significantly higher (P < 0.05) during the day (176) than at night (11). The fish showed a negative allometric growth pattern (b < 3). Monthly condition factor ranged from 2.0 to 3.2 and varied with individual fish length. Condition factor was higher during the wet season months. The baseline ecological data obtained for the first time on this species in the river, a first-order tropical stream in the Niger Delta, will provide information for future fish growth and food analyses, as well as for fisheries exploitation, management and conservation.