Dietary salt supplementation for juvenile mullet Mugil platanus reared in freshwater

Date

2011

Authors

Journal Title

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Abstract

Dietary salt supplementation for seawater/euryhaline fish reared in low salinities and/or freshwater might spare energy expenditure for osmoregulation allowing more energy for growth. Growth of mullet Mugil platanus is hampered in hypoosmotic environments, thus the objective of this study was to evaluated the effect of dietary salt supplementation on their performance when reared in freshwater. Two hundred and forty fish (4.50 ± 0.07g e 7.41 ± 0.03cm) were randomly distributed into 16 tanks (50L). These tanks were connected to a recirculating aquaculture system (RAS) equipped with UV sterilization, mechanical and biological filtration and temperature controller. A commercial diet (32%CP and 1.5% NaCl) was grinded to powder, supplemental salt was added, and cellulose was used to compensate for the extra salt. Fish were fed 3 times per day on diets supplemented with 0, 3, 6, and 9% NaCl. During the experiment, fish were maintained at temperature of 27 ± 0.1°C, oxygen saturation above 89%, 78.56 ± 1.09, 7.92 ± 0.02 and photoperiod 14C:10E. Fish were fed three times per day until apparent satiation. Biometry was made every 15 days. The data (average ± SE) were analyzed by analysis of variance (One-Way) (ANOVA) followed by Test of Tukey. All analyses were performed with significance level of p<0.05 and were conducted using the software statistic 6.0. Dietary salt supplementation did not affect survival of juvenile mullet, survival was above 90% in all tanks. Feed efficiency was not influenced by the experimental diets either, it averaged 0.31 ± 0.01 (p>0.05). However, final weight of juvenile mullet fed NaCl-enriched diets (6 and 9%) was significantly smaller than fish fed control or NaCl-enriched (3%) diets (p<0.05) (Figure 1). Considering the specific growth rate, juvenile mullet fed NaCl-enriched diet (9%) showed the poorest performance when compared to fish fed any other diet (Figure 2). Results indicated that diets supplemented with NaCl are not beneficial to juvenile mullet. Furthermore, excess salt (6% and 9% NaCl) are harmfull and compromise their growth

Description

Keywords

OSMOREGULATION, NUTRITION, GROWTH, RECIRCULATING AQUACULTURE SYSTEM, FISH CULTURE

Citation

URI

http://hdl.handle.net/10625/49789

DOI

Collections

IDRC Research Results / Résultats de recherches du CRDI
2010-2019 / Années 2010-2019
Battling pollution in coastal areas / Lutter contre la pollution dans les zones côtières