Palatability of Water Organisms for Nile Tilapia Oreochromis niloticus (Cichlidae)

Abstract

The palatability of six species of aquatic animals and five species of plants for the Nile tilapia Oreochromis niloticus was evaluated. Aqueous extracts of most organisms (ten of 11 species) have an attractive taste, which corresponds to euryphagia and nutritional plasticity of the Nile tilapia. Despite phytophagia, the palatability of an animal extract is higher than that of plants. The low stimulating effect of the extract of the duckweed Lemna minor suggests the presence of natural taste deterrents in it. The extract of the Canadian waterweed Elodea canadensis, depending on the origin of the plant, either completely blocks consumption or has inert taste properties. Different parts of the water hyacinth Eichhornia crassipes (leaves, roots) have a similar palatability. Repeated grasps manifested during orosensory testing of food are not typical for feeding behavior of the Nile tilapia. The results of the study indicate the ability of fish to subtly differentiate food organisms according to their taste qualities and emphasize the important role of taste reception in the choice of food objects by fish.