Influence of diet on the survival of Fingerlings Colossoma macropomum (female) x Piaractus brachypomus (male) and their repercussion on water quality.

Appropriate feeding practices in pisciculture consist in adjusting food ration according to the requirements and phase of growth of the species to cultivate, avoiding the loss of food and overfeeding. This affects the survival of the fish, the physical-chemical characteristics of the water and increases production costs. With the objective to evaluate the influence of the diets in the survival of cachamoto fingerlings and their repercussion in the water quality, an assay was performed in the Laboratory of Agricultural Zoology, in the University of East Monagas Nucleus, Maturin, Venezuela, using 96 fingerlings with initial weight of 2.30 g, distributed in 12 clear glass aquariums, with useful capacity of 40 L, with density of 8 fish/aquarium, providing four diets with two protein levels 25 % and 45 %, respectively, with and without phytoplankton. The feeding frequency was twice daily, considering 10 % of the biomass adjusted to 7 %. The results showed less mortality in diet 2 with 25 % of protein plus phytoplankton (survival 100 %) and diet 1 with 25 % of protein (survival 75 %). The highest mortality rate registered was in diet 4 of 45 % of protein plus phytoplankton (survival 25 %) and diet 3 of 45 % of protein (survival 29 %). The parameters of the water: temperature (29.25 degrees C), total dissolved solids (0.23 mg L-1), electrical conductivity (0.47 mu S cm(-1)) and pH (6.44) did not affect the survival or water quality, staying within the acceptable limits for the species, but the nitrites (2.76 mg L-1) and nitrates (33.67 mg L-1) influenced in these two aspects. The diet with 25 % of protein plus phytoplankton registered greater survival and maintained the quality of the water in the cultures of cachamoto fingerlings.