Development of a static-water ecoassay with microcosm tanks for postlarval Penaeus vannamei

A static-water ecoassay was developed to quantify the chemical impact of unassimilated nutrients and metabolic wastes on water quality in aquaculture, Using shrimp as the test animal, increased stocking densities and feeding rates increased nutrient loading in the water column. A stocking density and feeding rate that resulted in high weight gain (28%/day) and survival (89%) of Penaeus vannamei postlarvae (PL) were selected as appropriate for evaluating feed formulations. At the end of the 21-day growth trial, mass-balance analysis accounted, on average, for 90% of the phosphorus and 85% of the nitrogen that had entered the culture system. Assimilation of phosphorus and nitrogen into shrimp biomass averaged 25% for phosphorus and 63% for nitrogen. This static-water ecoassay has good potential for laboratory evaluation of nutrient dynamics in shrimp culture using 5- to 10-day-old PL at a stocking density of 1.5 PL/1 (444 PL/m(2)) and a high variable feeding rate. (C) 1998 Elsevier Science B.V.