Catfish hybrid Ictalurus punctatus x I. furcatus exhibits higher resistance to columnaris disease than the parental species

We present experimental data on susceptibility to columnaris disease, caused by the bacterium Flavobacterium columnare, in hybrid catfish (female channel catfish Ictalurus punctatus x male blue catfish I. furcatus) (CxB). Under our experimental conditions, CxB hybrids were significantly more resistant to columnaris disease caused by the highly virulent strain of F. columnare BGFS-27 (genomovar II) than channel catfish and blue catfish. Channel and blue catfish cumulative mortalities after immersion challenge were 74 and 87%, respectively, whereas mortality in the CxB hybrid was 31%. Susceptibility to the strain ARS-1 (genomovar I) was lower among all catfishes, although channel catfish was the least resistant species at 32% cumulative mortality. By contrast, CxB hybrid and blue catfishes were strongly resistant to the ARS-1 strain, with <10% mortality. Our data suggest enhanced disease resistance of the CxB hybrid to columnaris disease.