Efecto de la ración alimentaria en la acumulación amonio y supervivencia de Dormitator latifrons

Abstract

Objectives. Evaluate the effect of the food ration on the accumulation of total ammonia nitrogen and the survival of juveniles of D. latifrons under experimental conditions. Materials and methods. A completely randomized experimental design was implemented, without 72 h water replacement, 10 fish per replicate and three replicates per treatment, with feed rations of 2, 4, 6 and 8 % in relation to biomass and 35 % protein balanced shrimp feed. Water quality parameters were recorded daily, and dead organisms were counted. Results. Total ammonia nitrogen concentrations ranged from 1.05 to 7.80 mg*L-1 and non-ionized ammonium ranged from 0.33 to 2.27 mg*L-1. The feed ration at 2 % showed values of total ammoniacal nitrogen (5.16 ± 1.70 mg*L-1) and non-ionized ammonium (1.56 ± 0.48 mg*L-1) significantly (p < 0.05) higher than the other treatments; however, it showed the highest survival (100 – 56 %). Survival was reduced in all treatments; rations of 6 and 8 % recorded mortality from 24 h. LD50 % at 72 h was estimated with a food ration of 5.54 % with respect to biomass. Conclusions. Dormitator latifrons resists concentrations of non-ionised ammonium above 1 mg*L-1. In intensive cultures of D. latifrons, a food ration less than 4 % of biomass should be used, with water replacements at least every 48 h to avoid mortalities.