Influence of salinity on growth increment, feed conversion and body composition of common carp, Cyprinus carpio (Linnaeus, 1758) fingerlings in the captivity

Present study was conduct to observe the effect of salinity levels (5‰, 10‰, 15‰, 20‰ and 25‰) on growth increment, feed conversion and body composition of Common carp, Cyprinus carpio (mean body weight 5±0.01 g) were examined. Fingerlings were randomly distributed into the glass tanks (60×30×45 cm each). 10 fish per tank with two replications. Fish were fed with floating pelleted feed having 35% protein with 3% body day^-1 for 60 days. Results shows that the growth increment reared on 5‰ - 15‰ salinity were significantly highest in term of weight gain, WG % of initial weight, daily weight gain, specific growth rate, condition factor and survival rate than those reared on 20‰ and 25‰ salinity, feed conversion ratio were found similar in all levels which is not significantly different (p 0.05) in all levels. Whole body composition i.e. crude protein (14.62 –15.48), moisture (77.11 –77.81), crude fat (3.52–3.61), ash (3.66–3.71) contents of fish whole body were not significantly (p 0.05) different in various salinity levels. Mean values of water quality were found acceptable for common carp i.e. temperature 28.08± 0.13°C, dissolved oxygen 7.4± 0.07 mg L^-1, pH 7.7±0.01 and ammonia 0.023±0.004 mg L^-1. Relationship between Log body weight and log total length of the present study shows that fingerlings reared on 5‰ ^-15‰ was significantly (p 0.05) higher than 20‰ and 25‰ salinity levels. Histology of gills shows normal appearance of gill filaments and gill lamellae up to 15‰ salinity. Present results prove that Common carp can be reared up to 15 ‰ salinity to get good growth and higher survival rate.