Evaluation of selected metal nanoparticles on hatching and survival of larvae and fry of Indian major carp, rohu (Labeo rohita)

Different laboratory synthesized metal nanoparticles viz. Copper oxide (CuO), Zinc oxide (ZnO) and silver doped titanium dioxide (Ag-TiO2) were studied for their effect on hatching and survival of larvae and fry of Indian major carp, rohu, Labeo rohita both in direct application in tank water & coated onto tanks. Among these nanoparticles, CuO and ZnO nanoparticles exhibited highest percentage of hatching in both direct addition (78.0 ± 3.1% and 78.05 ± 4.2%, respectively) and coating onto tanks (58.6 ± 2.1% and 61.2 ± 2.7%, respectively) at 1 mg mL−1 while least percentage of hatching was recorded in Ag-TiO2 nanoparticles irrespective of its concentration & mode of supplementation. Highest survival of L. rohita fry (50.13 ± 2.2%) was observed after 15 days post hatching in CuO coated tanks followed by ZnO coated tanks (38.6 ± 2.8%) while least was recorded in Ag-TiO2 coated tanks (22.53 ± 3.0%). However in control tanks coated with Poly-Urethane base with hardener and uncoated control tanks, the survival was 42.4 ± 1.2% and 41.36 ± 1.8% respectively. Further, significantly lower microbial load of water was recorded in CuO nanoparticles coated tanks (1.5 × 1010 CFU L−1) as compared to uncoated control tanks (1.1 × 1016 CFU L−1) without affecting water quality parameters. On the other hand, in Ag-TiO2 coated tanks, significantly lower microbial load (1.0 × 106 CFU L−1) as compared to uncoated control tanks at 15 days post hatching was recorded. However, Ag-TiO2 was toxic to L. rohita larvae & fry both in direct application and coating onto tanks. Considering the beneficial effects of CuO nanoparticle application, it has the scope of being used in a more eco-friendly way in hatchery operations.