Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2011
Publication Date: 7/27/2011
Citation: Green, B.W., Rawles, S.D. 2011. Comparative production of channel catfish and channel x blue hybrid catfish subjected to two minimum dissolved oxygen concentrations. North American Journal of Aquaculture. 73:311-319.
Interpretive Summary: Catfish farmers increasingly are interested in growing the hybrid catfish that is produced when a female channel catfish is mated with a male blue catfish because the hybrid is said to possess a number of positive attributes when compared to the purebred channel catfish, which is the fish most widely grown in the U.S. catfish industry. However, the performance of the hybrid catfish compared to the purebred channel catfish appears to be affected by the strain of maternal catfish and requires investigation. Channel catfish growth in ponds is affected by the concentration of dissolved oxygen in the water. Growth of channel catfish decreases as the lowest dissolved oxygen concentration catfish experience in the pond during a 24-hour period decreases. But little is known about how growth of the hybrid catfish is affected by dissolved oxygen concentration. An experiment was conducted to compare the production characteristics of the channel x blue hybrid catfish and purebred channel catfish, both of which shared the Jubilee strain of channel catfish as the maternal parent. Dissolved oxygen concentration in ponds was allowed to decline nightly to either 50% or 25% of the saturation concentration before mechanical aerators were activated to add oxygen to pond water. Growth and yield of fish in the high dissolved oxygen ponds was the same for channel catfish and hybrid catfish. Channel catfish in the low dissolved oxygen treatment grew and yielded less than in the high dissolved oxygen treatment, whereas hybrid catfish growth and yield was the same to both dissolved oxygen levels. Nearly three-quarters of the channel catfish from the low oxygen ponds were too small to process and would require additional growth to reach market weight. The results of this study provide farmers with fish performance information that they can use to guide their decision as to the most appropriate fish to stock in production ponds. Furthermore, the results of this study show the importance of maintaining pond dissolved oxygen concentration high enough to allow fast fish growth.
Technical Abstract: The effect of daily minimum dissolved oxygen concentration on growth and yield (kg/ha) of the channel catfish (Ictalurus punctatus) and the channel x blue hybrid catfish (I. punctatus female x I. furcatus male), which shared the Jubilee strain of channel catfish as the maternal parent, was evaluated in a 234-d study in 16 0.1-ha earthen ponds (15,113 fish/ha). Ponds were managed to maintain a minimum dissolved oxygen concentration of 25% or 50% of saturation. Each pond was equipped with an electric paddlewheel aerator (11.1 kW/ha). Each fish genetic group was fed a commercially formulated 32% of protein diets daily to apparent satiation. Net yield of channel x blue hybrid catfish did not differ from that of channel catfish, but mean channel x blue hybrid catfish individual weight was significantly greater. Net yield, individual weight, and feed consumption were higher for fish in the high compared to low dissolved oxygen concentration treatment. Fish genetic group responded differently to minimum dissolved oxygen concentration. Net yield, individual weight, and feed consumption for channel catfish were lower for the low dissolved oxygen treatment, whereas there was no difference in these variables between dissolved oxygen levels for the channel x blue hybrid catfish. Growth did not differ between fish genetic groups, but was faster in the high oxygen treatment compared to the low oxygen treatment. Channel catfish grew faster in the high dissolved oxygen treatment, whereas there was no difference in channel x blue hybrid catfish growth between high and low oxygen concentrations. Mean hours of daily aeration and total aeration hours were higher for the high dissolved oxygen treatment.