Embryonic development and growth performances of an endangered fish species Nandus nandus: effects of dietary polyunsaturated fatty acids supplementation

The present study explored the embryonic and larval development of an endangered fish species Nandus nandus and resolved larval growth performances with the dietary supplementation of different types of lipids. Fertilized eggs were collected from fiber glass tanks immediately after spontaneous spawning of N. nandus, which were fed with a ۱% phospholipid (squid meal) supplemented diet for ۳ months. Fertilized eggs were transparent, spherical, yellowish and sticky in nature. The first cleavages of eggs were observed ۰.۳±۰.۰۱ h post fertilization at ۲۶oC water temperature. Hatching started around ۱۸ h post - fertilization and newly hatched larvae were found to be ۱.۲±۰.۱ mm in length. First feeding started ۶۴.۰±۰.۳۰ h post hatching. After rearing for ۱۰ days, they were divided into ۴ groups and separately fed with only dry tubificid worms, ۱% docosahexaenoic (DHA) supplemented with dry tubificid worm, ۱% phospholipid  supplemented with dry tubificid worm and live tubificid worms as treatment I, treatment II, treatment III and treatment IV, respectively. After ۵۰ days of the trial, larvae of treatment II showed significantly (p<۰.۰۱) higher growth performances in length: ۳.۱۸±۰.۱۳ cm, weight: ۳۳۹.۸ ± ۳۶.۹۴ mg and survival rate: ۷۸±۲ % which were comparable to that of treatment IV, which showed the highest (p<۰.۰۱) length of ۳.۴±۰.۱ cm, weight of ۴۰۶.۶±۲۷.۹۹ mg and survival rate of ۹۷±۱ %. Larvae in treatment I showed the lowest growth performances in length: ۲.۷۳ ± ۰.۱۶ cm, weight: ۲۵۹.۸±۲۹.۹۷ mg and survival rate of ۶۳±۳ %. As this is the first record for the determination of embryonic and larval development of N. nandus with different lipid supplemented diets, it might be possible to save this endangered fish species by adopting this technology at field level.