Results show that specific growth rates of triploid hybrids, control hybrids and triploid rainbow trout, raised separately, are about equal after the ¢rst feeding. Growth of hybrids was found to be higher than for rainbow trout controls between days 110 and 200. Once breeding problems are worked out, these hybrids may be useful in culture as they show heterosis
for growth rate and are superior to rainbow trout and Black Sea trout. An increased growth rate was reported in the sunshine bass, a cross between the white bass (Morone chrysops) and the striped bass (M. saxatilis) (Smith 1988); Crosses of the silver carp bighead carp (Hypophthalmichthys molitrix Aristichthys nobilis) (Krasnai 1987); black crappie white crappie (Pomoxis nigromaculatus Pomoxis annularis) (Hooe, Buck & Wahl 1994); catfish hybrids between the African catfish (Clarias gariepinus),