Effects of C‐N ratio on growth, survival and proximate composition of Macrobrachium rosenbergii post larvae reared under a corn starch based zero‐exchange brackish water biofloc system

• Published in: Aquaculture research Vol. 52; no. 7; pp. 3015 - 3025
• Main Authors: Hosain, Md. Eilious, Nurul Amin, Sarker Mohd, Kamarudin, Mohd Salleh, Arshad, Aziz, Romano, Nicholas
• Format: Journal Article
• Language: English
• Published: Oxford Hindawi Limited 01.07.2021
• Subjects: Ammonia; Biofloc technology; Brackish water; Carbon; Carbon sources; Carbon-nitrogen ratio; Ciliates; Composition; Control; Conversion ratio; Corn; C‐N ratios; Feed conversion; Food conversion; Freshwater crustaceans; giant river prawn; Growth rate; Larvae; Macrobrachium rosenbergii; maize starch; Marine crustaceans; Nematodes; Nitrogen; Nitrogen dioxide; Nursery grounds; nursery operation; Proximate composition; Starch; Survival; Tanks; Water exchange; Water quality; Water quality management; Water tanks; Zooplankton
• ISSN: 1355-557X; 1365-2109
• DOI: 10.1111/are.15146

A 3‐week nursery phase for giant river prawn, Macrobrachium rosenbergii post larval (PL), was conducted in biofloc systems at increasing carbon–nitrogen (C‐N) ratios of 10:1 (C‐N10), 15:1 (C‐N15), 20:1 (C‐N‐20) and 25:1 (C‐N25) versus a clear water system (40% water exchange every 2 days and no additional carbon). A total 400 PLs (15.90 ± 1.29 mg) were cultured in tanks (100 L) filled with brackish water (12‰), and corn starch was the carbon source. Growth, survival, feed conversion ratio (FCR), whole body proximate composition, water quality parameters, biofloc volume, zooplankton and proximate composition were measured. Total ammonia nitrogen (TAN) and nitrite nitrogen (NO2‐N) were significantly lower in all biofloc systems as well as containing increased zooplankton groups (ciliates, rotifers and nematodes). Specific growth rate (SGR) was similar between the control (9.29 ± 0.35% day−1) and the CN‐20 (9.47 ± 0.18% day−1) and CN‐25 (9.34 ± 0.20% day−1) treatments; however, SGR significantly declined in the C‐N10 treatment (8.03 ± 0.10% day−1). Survival was unaffected by treatments while a higher survival (87.34%) was in CN‐20 and it was followed by CN‐25 (80.34%), control (80.33%), CN‐10 (77.0%) and CN‐15 (76.66%) respectively. The best FCR was in the C‐N20 treatment at 2.65, but was not statistically different than the control at 3.12. However, crude protein of the PLs was significantly higher in the C‐N15, C‐N20 and C‐N25 treatments compared with the control. The present findings indicate that the water quality was better managed in the biofloc treatments compared with the control; however, lower C‐N ratios of 10 and 15 can negatively impact prawn growth compared with the control or higher C‐N ratios of 20 or 25.