Scientists help build a more resilient catfish industry

Catfish farmers in the United States had revenues of $421 million in 2021, up 12% from $377 million the previous year, according to the USDA’s National Agricultural Statistical Service. The top four states (Mississippi, Alabama, Arkansas and Texas) accounted for 97% of total US sales.

With support from USDA’s National Institute of Food and Agriculture, researchers at Land-grant Universities conduct research that supports the catfish industry (the largest part of U.S. aquaculture) and helps build a more resilient food system.

Understanding the effect of increased water hardness in catfish aquaculture

In Arkansas, the birthplace of the commercial catfish industry, University of Arkansas at Pine Bluff scientists have discovered the level of water hardness that is deadly for channeling catfish. Hardness is one of the integral water quality parameters that determines the success of aquaculture efforts. Proper water hardness is required for bone development, blood clotting, enzyme activity, eggshell integrity and embryonic development in fish. Most fish species perform well over a wide range of hardness values, but can suffer if hardness values ​​are too low or too high. Optimal requirements are often species specific.

In southern states, including Arkansas, fish producers experience significant changes in total hardness due to water evaporation during the summer months or due to dilution of pond water during periods of high rainfall. This ultimately affects overall fish productivity. For successful fish farming it is important that increased hardness remains within the safe range of the farmed fish species. However, information on the maximum safe tolerance for hardness is lacking for catfish or other fish.

Researchers found that, despite channel catfish having ways of coping with high hardness, exposure to calcium carbonate levels of 1500 mg/L and above was harmful. The results provide a guideline for the “maximum level” of hardness a farmer can safely raise in a catfish aquaculture system. As such, the result of this work can be applied in aqua farming worldwide.

Improving the health of catfish

Mississippi State University researchers are investigating diseases that limit the production efficiency of commercially farmed catfish. Scientists are developing rapid, molecular-based diagnostic tests for use in disease surveillance, disease treatment and prevention, and best management practices that reduce the impact of infectious and non-infectious diseases.

The research focuses on practical problems in catfish health or disease that limit catfish production in the southeastern United States. These include identifying emerging pathogens in and developing disease diagnostic methods for field surveillance studies; development of primary catfish cell lines for identification and confirmation of fish viruses; determining the distribution of channel catfish virus (CCV), and evaluating trends in the occurrence and virulence of different genetic strains of CCV in channel and hybrid catfish; and optimizing vaccine delivery and evaluating the economic impact of a live attenuated vaccine.

Preventing losses in catfish aquaculture due to algal toxicosis

Fish losses attributed to episodes of toxic algae remain a major problem facing aquaculture in Arkansas. In the late 1990s, Arkansas catfish producers lost an estimated $900,000 annually to catfish attributed to this problem. Today, these losses would equal $1.68 million.

The University of Arkansas in the Aquaculture/Fisheries Program of the University of Arkansas at Pine Bluff has adopted a proactive approach to an algae monitoring program. This program is ongoing to this day. An Renewal Specialist visits the farms weekly during the production season, for 40 or more weeks. Algae samples are collected weekly from approximately 166 ponds. The samples are examined microscopically with the presence and abundance of the algae, Aphanocapsa, noted. When the algae population exceeds the estimated 5 million cells per liter, treatment with an approved algicide is recommended. In some cases, flushing the affected ponds with massive amounts of water from adjacent ponds has also worked to reduce the number of culprits.

More than 2,800 algae samples were processed during the 2021 production season. Pond owners were advised to treat the algae 10 times. The program was successful in 2021. No economic losses were attributed to algae toxicosis. Treating the affected ponds saved an estimated $200,000 worth of catfish.

Top photo: left image of catfish producers holding a captive catfish. Right image of catfish swimming. Images courtesy of Adobe Stock.

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