EFFICACY OF THE BIOFLOC SYSTEM WITH THE ADDITION OF CHITOSAN ON TIGER PRAWN (Penaeus monodon) PRODUCTIVITY

Abstract

Penaeus monodon (tiger prawn) farming failures often occur in the post-larval initial stocking phase until harvesting. High mortality rates of P. monodon post-larvae are often observed after stocking. Disease attack in the second month of the rearing period eventually causes failure in extensive ponds. The primary objective of this study was to investigate the impact of chitosan addition on P. monodon yield in a biofloc technology (BFT) culture system. The experiment was performed in triplicate using three treatments, i.e., AL (a control pond without biofloc), ABF1 (a biofloc pond without chitosan addition), and ABF2 (a biofloc pond with 100 mg/L chitosan). The post-larval P. monodon (PL-10), which was visually healthy and disease-free, was obtained from a hatchery. The stocking density used in this study was 40 individuals per 100 L. The prawns were fed a commercial diet four times daily for 40 days. A statistically significant difference was observed (P < 0.05) in weight gain (0.213 - 0.299 g), average daily growth (0.0054 - 0.0074 g/day), specific growth rate (13.4 - 14.3% per day), survival rate (62.5 - 68.33%), food conversion ratio (1.14 -1.79), and protein efficiency ratio (2.41 - 3.33) of prawn among all of the treatments. Biofloc treatment with the addition of chitosan showed better prawn growth than that in the control and ABF1 treatments, with a weight gain of 0.30 g, average daily growth of 0.00075 g/day, specific growth rate of 14.3%, survival rate of 68.33%, food conversion ratio of 1.14, and protein efficiency ratio of 3.33. The inclusion of chitosan in the biofloc system led to a prominent increase in floc volume and heterotrophic bacterial populations while simultaneously reducing the number of Vibrio-like bacteria (VLB) colonies. No notable variations were noted in the food conversion ratio (FCR), total length, survival rate, total nitrite-N, nitrate-N, and total ammonia nitrogen levels. Biofloc technology supplemented with chitosan was found to boost the growth rate of P. monodon by enhancing both the water quality and the microorganisms in the ponds. The findings of this study provide a fundamental contribution to sustainable intensive shrimp farming practices through the implementation of biofloc technology, thereby enhancing productivity and maintaining environmental conditions in aquaculture.