The standardisation and optimisation of a one step single tube reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) procedure is described for rapid diagnosis of white tail disease, a viral disease caused by Macrobrachium rosenbergii noda virus (MrNV) and extra small virus (XSV), in giant fresh water prawn, M. rosenbergii. Time, temperature and quantity of each reagent were optimised for the detection of the two viruses. This method was more sensitive than the conventional reverse transcriptase polymerase chain reaction (RT-PCR) for detecting the two viruses. The RT-LAMP reaction is highly suited for disease diagnosis in developing countries. Amplification of DNA can be detected without the use of agarose gel electrophoresis, by the production of a whitish precipitate of magnesium pyrophosphate as a by-product. The cost of RT-LAMP for one reaction is nearly 4 times less than that of RT-PCR.

Shrimp processing waste is the single largest industrial waste in India causing diverse environmental problems. Extraction of carotenoids from the shell waste of the Arabian red shrimp Aristeus alcocki was investigated using different organic solvents, and vegetable oils, under wet and dry conditions, with and without deproteinization. The highest carotenoid yield was obtained with non-deproteinized wet waste extracted using acetone. The carotenoid yield was found to be double that of Pandalus borealis shell waste, which is currently used as one of the commercial sources of natural astaxanthin. Thin Layer Chromatography (TLC) analysis of the carotenoid extract showed that it contains free astaxanthin, astaxanthin monoester and astaxanthin diester in the ratio 1:1:2. gas chromatography (GC) analysis of the fatty acids esterified with astaxanthin revealed that saturated fatty acids, monounsaturated fatty acids and poly unsaturated fatty acids (PUFAs) are in the ratio 5:3:2 in monoester, whereas in diester they are in the ratio 4:3:3. The main fatty acids in monoester and diester are palmitic acid, oleic acid, stearic acid and -3 PUFAs: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The in vitro antioxidant activity of the carotenoid extract showed significant hydroxyl radical scavenging activity, superoxide anion scavenging activity and inhibition of lipid peroxidation at nanogram levels. The carotenoid extract significantly reduced carageenan induced paw edema in mice, percentage inhibition being 47.83 and 67.11 percent at astaxanthin concentrations of 0.5 mg/kg body weight and 1.0 mg/kg body weight, respectively. The inhibition of inflammation at 1.0 mg/kg body weight was greater than that produced by the standard reference drug diclofenac. The strong antioxidant and anti-inflammatory activities exhibited by the carotenoid extract of the shrimp shell might be due to the combined action of astaxanthin and -3 PUFAs present in the astaxanthin esters.

The efficacy of pharaoh cuttlefish (Sepia pharaonis Ehrenberg, 1831) liver lipid in the feed for juveniles of giant freshwater prawn Macrobrachium rosenbergii (De Man 1879) was tested by feeding five experimental diets prepared using clam meat, groundnut oil cake, wheat bran, tapioca powder, vitamin–mineral mixture and cellulose powder as the major ingredients. The test diets T1, T2, T3, T4 and T5, containing five levels (1, 2, 3, 4 and 5%, respectively) of lipid, extracted from the liver of pharaoh cuttlefish, were fed to 30‐day‐old prawn juveniles for 60 days, in triplicates and compared against a control. Analysis of variance of the growth parameters showed that the juveniles fed with T2, containing 2% cuttlefish liver lipid with a total lipid content of 9.85% and lipid–carbohydrate ratio of 1 : 3.8, showed significantly better growth (P < 0.05) with the highest weight gain of 118%, greatest food conversion and protein utilization efficiency, and the highest body protein content, although the survival rates remained unaffected among treatments. Growth of the juveniles, however, declined at lipid levels >2%. Addition of cuttlefish liver lipid led to an increase of ω‐3 and ω‐6 fatty acids in T2, the proportion of ω‐6 being higher than the former. The crude lipid content of the body of test animals also increased with the increase in dietary lipid from 1.51% in T1 to 3.27% in T5. The present study indicates that cuttlefish liver lipid can be successfully used as a substitute for conventional lipid sources in rearing juveniles of giant freshwater prawn, an eco‐friendly practice in recycling cuttlefish waste – a discarded fishery by‐product.

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