No abstract

Survival and growth of tiger shrimp (Penaeus monodon) at three salinity levels, 5, 10 and 15 g/L were investigated in potassium deficient natural inland saline water (PD-ISW) and potassium supplemented inland saline water (PS-ISW). Shrimps reared in PS-ISW survived well, whereas total mortality occurred in PD-ISW. The survival at 45 and 60 days at the salinities of 5, 10 and 15 g/L was assessed in PS-ISW. The supplementation of potassium showed significant effect on the survival rates at different salinities. Length-weight studies at different salinities and periods of time in PS-ISW showed significant differences in the linear component, but there was no significant difference in respect to interaction of salinity and rearing periods in a two-way ANOVA repeated measures. Growth parameters indicated that a salinity of 10 g/L was best for the survival and growth of shrimps in inland saline water of the site with potassium supplementation. Individual cations and ratios between other cations were found to be equally important for survival and growth. The results of the present study will be useful in utilizing degraded ISW sites for the culture of tiger shrimp.

No abstract

Potassium deficient inland saline (10 g L −1 salinity) well water was supplemented with muriate of potash to achieve 50% (57 mg L −1 ) and 100% (114 mg L −1 ) of seawater potassium concentration and used for the production of tiger shrimp ( Penaeus monodon). Total mortality was observed in non-supplemented water within 6 days compared to 88.0% survival in K + 100% and 85.3% survival in K + 50% up to 60 days. P. monodon were subsequently cultured for 110 days in two identical 0.25-ha ponds supplied with water of 10 g L −1 and supplemented with the potassium equivalent of 35% of seawater. Survival and production were 55.8% to 64.25% and 157.70 kg (630.8 kg ha −1 ) to 172.75 kg (691 kg ha −1 ), respectively.

A feeding trial was conducted to study the e¡ect of dietary protein (DP) levels on the growth and digestive enzyme activities of di¡erent wild stocks of Macrobrachium rosenbergii juveniles. Wild juveniles of M. rosenbergii were collected from the west coast of India, Gujarat (G), Maharashtra (M) and from the east coast of India, Andhra Pradesh (A), and raised in culture ponds of 200 m 2 at 1juvenile m À 2 . All the animals were tagged individually with Elastomer tags of a particular colour assigned to their respective stock and acclimatized for 7 days before being released into the pond at a ratio of 70:65:65 (A:M:G). Each of the two feeds, the ¢rst with 27% DP, termed the suboptimum level (S), and the second 32% DP, termed the optimum level (O), was fed in duplicate ponds at 6% of the body mass for the ¢rst 30 days and 4% for the last 30 days. The average weight of stocked prawn, respectively, in O DP and S DP fed ponds was 0.90 AE 0.04 and 1.06 AE 0.08 g for the G stock, 0.80 AE 0.07 and 1.01 AE 0.1g for the M stock and 3.06 AE 0.13 and 3.10 AE 0.23 g for the A stock. Both the protein level and the stock type had a significant (Po0.05) e¡ect on the weight gain% of the prawn. There was an approximate 95% change in weight gain with a DP change. Similarly, G and M stocks exhibited signi¢cantly higher (Po0.05) growth rates of approximately 90% than the A stock, although no di¡erence was noted between the G and the M stocks. However, for protein  stock (interaction) levels, there was no signi¢cant di¡erence (P40.05) among the groups. Although insigni¢cant, the survival rates among the di¡erent stocks varied from 56% to 77%. Optimum protein level showed a signi¢cant increase (Po0.05) in the speci¢c growth rate (SGR). Feed conversion ratio, feed e⁄ciency ratio, protein e⁄ciency ratio and net protein utilization were not a¡ected either due to DP, stock type or their interaction. The O  A group exhibited the maximum variation in body weight. Digestive enzyme activities were similar in all the groups, but enzymes for phospho-monoesterase were signi¢cantly higher (Po0.05) at O DP. Both the G and the M stock showed a signi¢cantly higher (Po0.05) alkaline phosphatase activity while acid phosphatase activity was signi¢cantly higher (Po0.05) in the M stock only. Overall, the G and M stocks showed higher growth responses compared with the A stock. Material and methods Experimental animals and taggingWild juveniles of M. rosenbergii were collected from Godavari River, near Rajamundary, in Andhra Pradesh (East coast); Surya River, near Palgarh, in Growth and digestive enzymes of M. rosenbergii juveniles V Sagar et al.