Monosex populations of channel catfish have been developed through hormonal manipulation of sex and subsequent breeding programs. Broodfish that will produce only male offspring have been developed. However, no heteromorphic sex chromosomes are present. Consequently, sex genotypes of fish with altered sex phenotypes must be determined by progeny testing. Molecular markers associated with sex in other animals are expressed equally in male and female channel catfish.
Efforts are underway to identify other sex-linked genes.
A long-term goal is to develop a molecular probe to identify the genotypic sex of individuals which would obviate the need for progeny testing. Gynogenetic techniques have been used to produce populations with reduced genetic variability. Analysis of recombination rates has permitted the development of genetic maps for a few loci. Unexpected sex ratios derived from broodfish produced by gynogenesis of sex-reversed females indicate the genetic control of sex determination may not be as direct as previously thought. Efforts are underway to better understand the genetic control of sex in channel catfish.