Effect of dietary protein level on growth performance and nitrogen excretion of the juvenile convict cichlid, Amatitlania nigrofasciata

Abstract

A 8 weeks growth trial was conducted to determine the effects of dietary protein on the growth of the convict cichlid Amatitlania nigrofasciata and on water quality in closed recirculating systems. Four test diets were formulated to contain protein levels ranging 30-45%. The fish averaging 0.47±0.07 g were reared in 10 L aquarium. Fish were fed ad libitum at 08:30, 12:30 and 16:30 for 8 weeks. A second-order polynomial regression between dietary protein levels and weight gain in each group, demonstrated that the most suitable protein level for maximum growth was determined to be 40.8%. The feed conversion ratios of fish ranged from 1.78-2.78 in the experimental groups. Results showed significant differences in SGR and WG. Dietary protein level significantly influenced ammonia excretion, fish fed 45% protein excreted higher concentrations of ammonia-nitrogen than fish fed 30-40% dietary protein. For optimum growth, feed conversion and ammonia excretion, a diet containing 40.8% protein, 12% lipid and 20.8 kJ gross energy/kg diet is recommended for juvenile convict cichlids, A. nigrofasciata. © Medwell Journals, 2014.