There has been a very rapid global expansion of freshwater prawn farming since 1990; this is mainly because of the huge production of China but also, in the last few years, because of a rapid take-off of farming in India and Bangladesh. Survival at the end of the nursery phase can vary substantially and may be related to the territorial and cannibalistic nature of prawn PLs when cultured at high densities. Nursery production may be enhanced by the addition of artificial substrates. Seed cost is a dominant variable cost in prawn production. Thereby, cost efficiency of nurseries significantly impacts the prices of stocker size juveniles, which in turn has a dramatic influence on the profitability of prawn grow-out. Therefore, investigation into potential benefits derived from using artificial substrates, a study was conducted in recirculatory system to evaluate the effects of substrates on the growth and survival of Macrobrachium rosenbergii postlarvae (PL). Result of the present study indicated that growth of M. rosenbergii PLs improved in presence of artificial substrates but the artificial substrates did not improved survival.

Currently two effective ways are used with the administration of a metronidazole composition. A single, large dose is given as a bolus to the patient which is clinically effective but a major drawback to the administration of single large dose of metronidazole is the occurrence of significant and undesirable side effects. A second and more generally accepted treatment entails orally administering smaller dose of metronidazole three time a day. The lower dosage of metronidazole over a period of a week significantly reduces the occurrence and severity of side effect but patient compliance is a problem can inadvertently forget to take one or more doses during the course of treatment, causing the plasma metronidazole level drop to bellow an acceptable therapeutic level for a period of several hours or more. Hence extended release formulation of metronidazole could be suitable alternative for reducing the number of daily doses needed to treat a microbial infection, while maintaining the benefit of making bioavailable effective amount of drug over an extended time period.

This book contains the findings of a study which was conducted for 60 days at the pond complex of the Freshwater Station of Bangladesh Fisheries Research Institute located about one kilometer away west of the Bangladesh Agricultural University, Mymensingh. The research was carried out to compare the performance of different nursing practices of giant freshwater prawn (Macrobrachium rosenbergii) post-larvae (PLs). Three treatments such as only fertilizers (T1), fertilizers with 5% supplementary feed (local feed) (T2) and 10% commercial feeds (T3) were applied in the nursing system of prawn PLs in earthen pond. The results showed that growth and survival in prawn nursery was better in commercial feed than only fertilizers and fertilizers with local feeds. So, this book will be helpful for those who are interested in prawn post larvae rearing, feeding and management in nursery ponds.