A Comparative Study to Investigate the Impact of Salinity on Breeding of tilapia-Red (Oreochromis niloticus×O. mossambicus)and tilapia-Nilotica(O. niloticus)in Captivity

Abstract

: Present study was conducted to get mass seed production of tilapia species, tilapia-Red (Oreochromis niloticus × O. mossambicus) and tilapia-Nilotica (O. niloticus) on different salinity (0‰ to 30‰ with 5% increment). Sexually mature and healthy brooders females having body weight of 145g-160g and male 140g-162g were selected andstocked in to net enclosure (hapa). Male and female ratio was 1:3 during experiment brooders were fed with formulated floating diet having 35% CP, 2% of total biomass in a day. Eggsfrom mouth of females were collected on weekly basis and incubated artificially. Results showed that highest degree of eggs, fertility rate and survival rateof hatchlings were obtained on salinity up to 20‰ (red tilapia)and up to 15‰(nile tilapia). Number of eggs/g / body weight were also calculated and found higher among both species i.e. 4.0 to 4.3 per female on 0‰ to 20‰in red tilapia and 0‰-15‰ in nile tilapia. Temperature of water was (28.5±0.2°C), dissolved oxygen (06.25±0.01 mg/L), pH-level (7.2±0.03) and ammonia-concentration (less than 0.021±0.001 mg/L) were monitored throughout the study period. Water quality parameters remained within the recommended range. Out-comes of current findings advise that tilapia-Red breed effectively up to 20‰ salinity with 70% survival rate of fry and Nile tilapia, O. niloticuscan breed successfully up to 15‰ salinity with 90% survival of fry.