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Abstract. Four cladoceran species of importance as fish food organisms, viz. Daphnia similes (Claus), Simocephalus vetulus (Schodler). Moina macrocopa (Straus) and Ceriodaphnia cornuta (Sars), were raised in the laboratory on nutrient sources including manures, rice bran and Chlorella. The organisms responded better with rice bran and Chlorella. The productivity of culture organisms appeared to depend upon inoculum and residual densities, indicating a relationship between periodic harvesting and increased production. Associated study reveals the importance of space per individual in the success of laboratory cultures. The optimum space requirement of each species determined by the size of culture organism may vary from 4·5cm3 per individual for small species like Ceriodaphnia to 41·8cm3 per individual for the larger species, Daphnia.

The freshwater crab, Paratelphusa masoniana was collected for a period of one year to investigate the seasonal fluctuation in the proximate composition. Marked seasonal variation in protein, lipid and moisture were observed during a period of one year to determine their viability in the course of the reproductive cycle. Both protein and lipid content are inversely related to moisture content. Maximum protein (62.15±0.30%; 55.85±0.48) and lipid (5.85±0.46%; 5.49±0.38%) were observed during non-spawning period and minimum during spawning months. The relationship between protein and lipid is however a direct one. On the basis of the investigation, it has been recorded that the local freshwater crab, P. masoniana, is a biannual breeder.

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Genetic variations among prawns act as an important tool to characterize and differentiate between the species. Molecular and phylogenetic analysis of shrimps and prawns like any other organism rely on high yields of pure and better quality genomic DNA. In this regard isolation of DNA is the first and basic step. In spite of the availability of many protocols of DNA extraction from animal tissues, it is difficult to ascertain that which one would provide desired results for prawn tissue. In the present study, three different techniques of DNA isolation i.e., salting out, phenol-chloroform and Qiagen DNA extraction kit were performed and compared for their yield. Cephalothoracic tissue and muscle tissue of pleopods were used for isolation. Tissue samples from fresh specimens as well as from alcohol preserved specimens were employed for extraction. The quantity (µg/ml) and quality of isolated DNA were determined by UV spectrophotometry and agarose gel electrophoresis. Results showed that Phenol-chloroform method with slight modifications obtained higher yield of genomic DNA as compared to other methods. The present work also revealed that among fresh specimens cephalotoracic tissue yielded high concentration DNA than muscle tissue. However, among alcohol preserved specimens, the concentration of DNA was higher in muscle tissue of pleopods. The high quality DNA was then subjected to randomly amplified polymorphic DNA (RAPD) and inter simple sequence repeats (ISSR) analysis. The DNAs produced clear, sharp and reproducible PCR (Polymerse chain reaction) product pattern.