Growth of channel catfish (Ictalurus punctatus), blue catfish (I. furcatus), and their F^sub 1^, F^sub 2^, F^sub 3^, and F^sub 1^ reciprocal backcross hybrids in earthen ponds

The F^sub 1^ hybrid between a channel catfish female (Ictalurus punctatus) x a blue catfish (I. furcatus) male outperforms both parental species in most environments. However, reproductive isolating mechanisms between the species made it difficult to mass produce the F1 hybrid for commercialization until recent improvements in hormone usage. This study was undertaken to mix the genomes of the 2 species in an attempt to obtain faster-growing catfish that would eventually be easier to reproduce. Despite the recent improvements, it would still be advantageous to have an animal that does not require hormone dosing for reproduction and does not require the growing of 2 separate species by breeders. Additionally, a F^sub 1^ backcross or a multigeneration backcross has the possibility of being an improvement compared to an F^sub 1^ hybrid. At low density, there was no difference in growth between channel catfish and channel-blue F^sub 1^ hybrids. At higher densities, the F^sub 1^ hybrid grew faster (666 g) than channel catfish (577 g), blue catfish x F^sub 1^ (520 g), F^sub 1^ x F^sub 1^ (508 g), F^sub 1^ x channel catfish (436 g), blue catfish (396 g), F^sub 1^ x blue catfish (379 g), channel catfish x F^sub 1^ (359 g), and F^sub 2^ x F^sub 2^ (359 g; P < 0.05). The channel-blue F^sub 1^ males were heavier than the F1 females. Individual heterosis had a strong positive effect on growth, whereas individual epistatic recombination loss had a strong negative effect on growth. The channel-blue F^sub 1^ hybrid and blue catfish had low coefficients of variation, whereas the F^sub 2^ and F^sub 3^ hybrids had high coefficients of variation. This gives a high amount of variation for selection, which might be used to select the faster-growing catfish.