Document Type : Original Article
Author
Central Laboratory for Aquaculture, Agricultural Research Centre, Ministry of Agriculture, Giza, Egypt
Abstract
Occurrence and composition of phytoplankton in stomachs of Nile tilapia (Oreochromis niloticus L.) in ponds received inorganic fertilizer (20:20:5 N:P:K) at different doses were studied. The doses were 0, 20, 40, 60 and 100 kg/feddan/month. It was found that, O.niloticus consume phytoplankton, detritus and zooplankton with different composition. The main items found in fish stomach were phytoplankton and detritus. Zooplankton was occasionally found and not exceeding 1.5% of total stomach contents. The main species of algae found in fish stomach belonged to Cyanophyta, Chlorophyta, Bacillariophyta and Euglenophyta. Detritus consisted mainly of scraps of macrophytes and mud. The most frequently species represented in fish stomach in all treatments were Anabaena sp, Merismopedia eleganse, Microcystis aeruginose, Nodularia harveyana and Oscillatoria sp (Cyanophyta). Cerasterias sp. Chlorella spp, Crucigenia sp, Pediastrum spp., Scenedesmus spp. and Tetraedron sp. (Chlorophyta), Amphora ovalis, Cocconeis placentula, Cymatopleura solsa, Cymbella cistula, Gyrosigma attenuatum, Melosira granulate, Navicula spp., Nitzschia spp. Pinnularia spp.. Serurella sp. and Synedra sp. (Bacillariophyta) and Eug/ena and Phacus spp. (EuglenophyI a). Results revealed that, O.niloticus could select Cyanophyta during the investigation period and sometimes select Bacillariophyta and arglenophyta.
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