#stocking density

Stocking density of fish depicts the number of fish that are stocked supplied at first per unit area. It is one of the most significant factors in determining the production of a fish farm. The stocking fish at low density results in high production costs, low economic gain and inadequate utilization of space. Increasing stocking density may activate stress response which negatively affects growth parameters, survival, behavior, health, feeding of fish. Different metabolic pathways related to lipid, carbohydrate and protein metabolism are also affected by this stress. So, for good yield fish should be stocked at optimum level. Optimum stocking density is the level where the maximum yields are reached. Fish are considered as a potential source of animal protein and essential nutrients in human diet. Amino acids, the building blocks of protein, act as a precursor of many enzymes, hormones, neurotransmitters, nucleic acids and other molecules essential for life. High stocking density affects amino acid profile of fish. The enzymatic activities and synthetic rates of functional proteins that is associated with responses of stress, HSD that is used as a stressor may influence amino acid requirements. High stocking density significantly affects water quality, growth parameters and amino acid profile of fish and it may induce stress in fish and may have negative impact on fatty acid profile if environmental conditions are not suitable for fish.

The effect of four (12, 18, 24, and 30 larvae L-1) stocking densities (SD) on growth and survival of catfish, Clarias batrachus larvae (1.47 cm and 0.03 g) was investigated in triplicates in glass aquaria for a period of 28 days. The larvae were fed with Tubifex sp. four times daily until satiation. The larvae reared at high SD (30 larvae L-1) showed significantly slower growth performance than those held at low SD (12 larvae L-1). Water quality parameters were found within the productive range (temperature: 28.7°C, DO: 6.1 mg L-1, pH: 7.8, and alkalinity: 379 mg CaCO3 L-1) for all treatments. The specific growth rate varied significantly in fish reared at high SD than at low SD on day 14 only, but on day 7, 21, and 28 there were no significant differences among the four treatments. Heterospecific growth was observed in high SD resulting in increased coefficient of variance of length and weight on final day. On the other hand, there was no effect of stocking densities on the survival rate of the larvae during the experimental period. Based on these findings, a stocking density of 18 larvae L-1 appears to be optimum for intensive culture of C. batrachus in indoor static water system.