Semen collection in catfish species, with particular emphasis on the African catfish.

Abstract

Abstract This minireview describes the current knowledge on semen collection in captive male catfish. It is well known that when some catfish species, such as the African catfish ( Clarias gariepinus and Heterobranchus longifilis ), channel catfish ( Ictalurus punctatus ), blue catfish ( I. furcatus ), Asian catfish ( C. macrocephalus ), and Indian catfish ( Heteropneustes fossilis ) are kept in captivity, hand-stripping of semen is impossible. To reproduce these species artificially, males are sacrificed and intratesticular semen is spread over the eggs. This is considered the major constraint in catfish culture, as both selection and genetic improvement are compromised. Different hormone treatments that either induce or mimic the prespawning gonadotropin surge have been tested with respect to their ability to induce semen release and possibly facilitate stripping of semen under abdominal massage. However, little or no success has been obtained. Recently, the effects of oxytocin on sperm transit in catfish have been tested, but the results are still not conclusive. It has been demonstrated that stripping of semen in catfish species is not possible because of an anatomical blockage. This has been observed in African catfish that have been fed on 17α-methyltestosterone (MT)-supplemented diet during larval stages and have developed without seminal vesicles but can be stripped following treatment with carp pituitary suspension (cPS). The efficiency of these hormone treatments and their ability to facilitate hand-stripping of semen in catfish species are discussed.