Food and feeding habits of some Nile River fish and their relationship to the availability of natural food resources

摘要

The present work aims to investigate the food items and the feeding habits of some Nile fish namely;Alestes baremoze,Labeo niloticus,Mormyrus kannumeandOreochromis niloticusthat were collected from El-Qanater Al-Khairia during spring 2018 as well as to study their correlation with live food. The examination of the plankton samples revealed that there were 25 phytoplankton species belonging to 6 phyla of the plant kingdom. The common phytoplankton phyla were Bacillariophyta, Chlorophyta, Cyanophyta, and Dinophyceae. Twenty-five species and other immature stages representing the zooplankton community were categorized in ten groups of the animal kingdom. The dominant groups were Rotifera, Protozoa, Copepoda, Cladocera and Polychaeta. The benthic fauna collected from the study area comprised of 7 groups of the animal kingdom represented in 10 species and other immature stages. The recorded groups were Mollusca, Foraminifera, Annelida, Insecta and Decapoda. The present results showed that the feeding intensity in the studied fish were moderate, being 60% inA. baremoze; 53.85% inL. niloticus; 66.67% inM. kannumeand 53.57% inO. niloticus. Analysis of the stomach contents revealed thatA. baremozeis a plankton feeder and consumed a wide range of phyto- and zooplankton.L. niloticusis majorly herbivorous and consumed a great variety of plant food.M. kannumeis mainly a carnivorous benthic feeder consuming a great range of animal food, whileO. niloticusis mostly omnivorous consuming high varieties of plant and animal food. The forage ratio of stomach contents showed thatA. baremozeandM. kannumeare selective feeders. However,L. niloticusandO. niloticusdepended on the food availability in nature and selectivity.