EVALUATION OF THE LEAF OF ZIZANIA LATIFOLIA AS A SUBSTITUTE FOR CEREAL STUFF IN PRACTICAL DIETS FOR HERBIVOROUS FISHES

Zizania latifolia is a feed crop of high quality. Two herbivorous fishes, Ctenopharyngodon idcllus and Magalobrama amblycephala were fed three diets with different contents of the leaf of Z. latifolia. The replacement level of Z. latifolia for cereal stuff in these diets were 10% (diet 1), 20%(diet 2) and 30%(diet 3) respectively. The addition of Z. latifolia slightly reduced the crude fat content, but did not affect the protein content of the diets. Growth rate and mortality of the fish fed different diets did not differ significantly. Feed conversion and the cost of feed needed to produce lkg of fish were lower for diet 2, but did not differ between the other two. As the amount of Z. latifolia added to the diet increased, the amount of cereal stuff needed in the diet can be reduced by 44—73.6%. An average fish yield of 23.7 kg/m2 was obtained by feeding the three diets for 126 days in cage-culture. The leaf of Z. latifolia can therefore be used as a substitute for cereal stuff in the practical feeds for herbivorous fish.