Observations on intergeneric hybrids in tilapias

This study describes the hatchability, growth, sex ratios and reproductive behavior of intergeneric hybrids between Tilapia zillii (Linneus) and Sarotherodon galilaeus (Linneus), and between T. zillii and Oreochromis andersonii (Castelnau), O. aureus (Steidachner), O. macrochir (Boulenger), O. mortimeri (Trewavas), O. mossambicus (Peters), O. niloticus (Linneus), O. placidus (Trewavas), O. spilurus (Gunther) and O.tanganicae (Gunther). Only hybrid crosses using T. zillii as the maternal parent were successful. Mean fertilization rates of the pure T. zillii cross and the hybridcrosses were similar and ranged from 91 to 98%. Hatching rates varied from 67 to 91%. The growth of the juveniles varied among the hybrids, but the growth patterns were similar to T. zillii x O. andersonii and O. tanganicae to all females in the T. zillii x O. niloticus, O. placidus and O. aureus. By convention, the female parent is named first. Thehybrids in all crosses produced mature gonads. The characteristics of the eggs in all crosses were closer to the maternal parent.