The study evaluated the suitability of replacing fish meal with a mixture of two plant proteins: cowpeas (Vigna unguiculata) and Amaranthus cruentus as a protein source in the diet of three weeks old Labeo victorianus on growth performance, nutrient utilization and carcass proximate composition. Fishmeal was replaced with the mixed vegetables at a ratio of 25%, 50%, 75% and 100% and the substitution effects compared with control diet containing fish meal as the sole protein source. The five dietary treatments were tested in triplicate in static flow through tanks for 90 days. The fish were fed four times a day at 4% body weight. After 160 days of feeding, growth, nutrient utilization and FCR in fish fed at 25% and 50% Vigna unguiculata) and Amaranthus cruentus were better than those fed 75% and 100% Vigna unguiculata) and Amaranthus cruentus but not significantly different from those fed with fish meals diets alone (F = 17.002, P = 0.002). Growth reduction, increased FCR and reduced nutrient utilization occurred with increasing plant inclusion in the diet beyond 50% inclusion levels. Thus it is possible to replace up to 50% of fish meal with a mixture of V.unguiculata and Amaranthus cruentus in the diets of L. victorianus. This will reduce the cost of production as fish meal is increasingly becoming expensive as its demand outweighs its supply.
This finding lends credence in the continued research into areas of utilization of alternative plant proteins sources in place of fishmeal based feeds as protein sources in improving aquaculture.