Microplate-based incubation method for quality assessment of eggs of Indian major carp Catla catla

Incubation of fertilised eggs from the Indian major carp species, Catla catla was carried out in tissue culture microplates to assess the quality in terms of hatching rate and post-hatch survival rate. Eggs from five females (F1, F2, F3, F5 and F6) were strip spawned and fertilised with milt from a single male. The fertilised eggs were distributed at one egg per well of 24 well microplates, with three plates for each female. The plates were incubated at 30oC in an incubator with continuous shaking and complete hatching was observed by 36 h. The hatching rate varied within a range of 0 to 52.8% showing the maximum of 5% for F5 followed by F1 (50%) which were significantly higher than the other three females (F2-18.1, F6-5.6 and F3-0%). The eggs from these two females (F1 and F5) thus could be considered as good. The survival percentage of hatchlings recorded for a period of 8 days post-hatching was found to vary from 58.3 to 83.3 and there was low variability among different females on any observed day. Thus, between these two egg quality determinants, the hatching rate was found to be more suitable considering the wide variability shown by different females indicating the quality difference. Thus, the microplate method seems to be an appropriate tool to assess the egg quality in catla and can be extended to other species as well.