The cichlids (family Cichlidae) of Rift Valley Lakes have high levels of endemism and are of particular interest to scientists researching the evolutionary mechanism of adaptive radiation occurring within short periods of time. African cichlids practice mouthbrooding parental care that ensures high survival rate of young. The cuckoo catfish (Synodontis multipunctatus) is the only known obligate brood parasite among fishes, and it uses the cichlid fish as a host to incubate their own eggs. In laboratory conditions previews studies show that Ctenochromis horei (parasitized in nature by cuckoo catfish) displayed more aggressive behavior toward the cuckoo catfish (S. multipunctatus) rather than the Metriclima zebra (not parasitized in nature). The goal of this study is to determine if egg size, larvae size or accelerated skeleton development differed between the C. horei and M. zebra in order to understand if there are other morphological charasteristic in the early stages of cichlid development that makes the parasitism of catfish more suitable. The cichlid eggs from both species were removed from females after spawning and maintained in a re-circulating incubator that mimicked the tumbling of the ducal cavity. Embryos were raised at 26.6°C and treated with methylene blue to minimize fungal infection. Egg size and larvae size was determined by measuring length using Axiovision software. From day one (1) post fertilization to day thirteen (13) post fertilization larvae were collected and fixed in paraformaldehyde to determine bone development using Axiovision software.

Results/Conclusions

Results showed no significant differences of larvae size and skeletal development between C. horei and M. zebra but there were significant differences in egg size. This shows that the catfish (S. multipunctatus) is more capable to succeed its parasitism using the M. zebra as a host rather than the C. horei because the egg size is smaller and easier to eat. This knowledge help to gather a broader view of behavioral dynamics of parasite and host species among fishes.