Substrate Addition and their Effect on Water Quality, Growth and Nutritional Composition of Penaeus vannamei in Biofloc-based Nursery System

Abstract

This study assessed the effect of different types of substrates integration in biofloc based nursery rearing system. The experiment was conducted comprising 100% of tank total surface area (0.86 m2). Twenty four experimental units of 100 L capacity were stocked with Penaeus vannamei PL-10 (5.0 + 0.00 mg) for 30 days. The experiment consisted of six treatments as a group without biofloc and without substrate as control, biofloc and biofloc with substrate (bamboo mat, HDPL sheet, mosquito net screen, shade net) with four replicates. Among the treatments, significantly higher (p<0.05) final weight (1.1035+0.005g), survival rate (94.42+0.68%) and lower feed conversion ratio (1.1782+0.0048) were recorded in F+BM system followed by F+MNS and F+SN treatments. The substrates except HDPL sheet affected water quality since the concentrations of total ammonia, nitrate, nitrite and total suspended solids were significantly different (p < 0.05) from other treatments. The crude protein (65.27+ 0.49) and crude lipid (2.75 + 0.09) of shrimp was significantly higher (p < 0.05) in tanks with bamboo mat as a substrate. The Bamboo mat proved to be the most suitable substrate for nursery rearing of P. vannamei in the biofloc system followed by artificial substrate as mosquito net screen and shade net essentially because it could maintain levels of solids suspended in biofloc. Also, the microbial community associated with substrate was mainly regulating water quality variables and biofilm formation on substrate serve as natural feed which enhances the concentration of crude protein in shrimp and bioflocs.