Scylla serrata (mud crab or mangrove crab), is an ecologically significant species of crab found in the estuaries and mangroves of Africa, Australia and Asia. Generally, their shell color varies from a deep, mottled green to very dark brown. According to Shelle and Lovatelli1, during 1990 to 2010; extraordinary boost was observed in the world production of crustacea up to 9.7% and crab production reached up to 200.000 t in 2010. Perhaps, limited crab supply leads towards stumpy production.
This particular species have to perform molting in which cannibalism occurred which is the major factor of enhanced mortality rates in mud crabs2. Moreover, supply of mud crab still relies on natural stock because of restricted cultivation methods. These factors are contributing towards least crab production. Accordingly, in 2013; crab export reached 34.173 t but unfortunately decreased to 28.091 t in 2014. However; demand of mud crabs is increasing day by day.
High light intensity could promote stress and mortality in some aquatic species3. Therefore, in order to deal with cannibalism, crab container should be designed with proper bright and dark condition; to improve growth performance by plummeting stress. Moreover, the colors of rearing media and container could considerably reduce light penetration in water4 and also could affect stress response of fish.
Yuni Puji Hastuti and co members conducted an experiment; to evaluate the most favorable container condition for survival and growth of mud crab by protein profile and ammonia excretion. For this purpose, mud crab having original weight 45-65 g were kept in containers (60×40×30 cm3) in recirculation systems for 42 days with feeding trash fish restricted by 5% twice daily. Two treatments with three replications of bright containers and dark containers were utilized during this research. Scientists also noted growth performance of crabs as well several stress indicators including protein retention, total serum protein, ammonia secretion.
It was observed that dark container exhibited better growth performance for nursery of mud crabs, with survival rate of 30%, growth rate of 0.44%/day, protein retention of 15.59% and total protein serum of 3.3%. Hence, researchers concluded that intensive crab farming could be conducted in controlled condition because mud crabs performed better by using dark container to enhance survival rate, growth rate. Moreover, this investigation will definitely pave a way to offer meaningful data for aquaculturists to increase mud crab production.
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17 November, 2019