Effect of the addition of diatoms ( N avicula spp.) and rotifers ( B rachionus plicatilis ) on water quality and growth of the L itopenaeus vannamei postlarvae reared in a biofloc system

The aim of this study was to evaluate the effect of the addition of N avicula spp. and B rachionus plicatilis on water quality and growth of postlarvae shrimp L itopenaeus vannamei reared in a biofloc system. Four treatments were considered: a control (biofloc system – BFT ); BFT with the addition of N avicula spp. ( BFT ‐N); BFT with the addition of B rachionus plicatilis ( BFT ‐B) and BFT with the addition of N avicula spp. and B rachionus plicatilis ( BFT ‐ NB ), each in triplicate. Shrimp (16.2 ± 0.03 mg) were stocked at a density of 2500 shrimp m −3 and plankton were added on days 1, 5, 10, 15, 20, 25 and 30 at a density of 5 × 10 4 cells mL −1 ( N avicula spp.) and 30 organisms L −1 ( B rachionus plicatilis ). The shrimp were fed a formulated feed in four daily rations composed of 40% crude protein and 8% lipids. Significant differences between treatments were observed for final weight, yield, feed conversion ratio, specific growth rate, protein efficiency ratio and protein content of the shrimp. The combined plankton addition of N avicula spp. and B . plicatilis had better performance parameters, indicating their benefit as natural food sources for postlarvae L . vannamei in biofloc systems.