Effect of supplying four copepod densities (Acartia sp and Calanus pacificus) on the productive response of Litopenaeus vannamei pregrown intensively at microcosm level

A seven-week experiment was performed to evaluate the effect of supplying copepods (Acartia sp. and Calanus pacificus), as exogenous feed during the intensive pre-growout phase of white shrimp (Litopenaeus vannamei), on the productive parameters and water quality. Five treatments were tested in which shrimp were fed formulated feed and the addition of 0 (control), 1, 2, 4, or 8 copepods mL(-1). Treatments with 1 and 4 copepods mL(-1) had higher ammonia nitrogen levels than the rest of the treatments (>4 mg L-1). Nitrite levels were significantly higher in the treatment with 8 copepods mL(-1), whereas nitrate levels were higher in all treatments relative to the control. Phosphate concentration was higher in the treatments with 4 and 8 copepods mL-1. Shrimp from the treatments with 2, 4, and 8 copepods mL(-1) showed a higher survival (>93%), weight (>3.1 g), and final biomass (>77 g). The treatment with 2 copepods mL(-1) had the best feed conversion ratio (1.19) compared with the rest (>1.7). The results suggest that the additional supply of copepods as exogenous feed during the intensive pre-growout phase of shrimp culture can have a negative effect on the water quality, although survival was not affected; however, the effect on the production parameters was positive, indicating that the use of copepods as exogenous live feed is feasible in the culture of white shrimp.