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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #177662
Title: EFFICACY OF FORMALIN AS AN EGG DISINFECTANT FOR IMPROVING HYBRID CATFISH (ICTALURUS PUNCTATUS X I. FURCATUS) HATCHING SUCCESS

Author
item Small, Brian
item CHATAKONDI, N - HARVEST SELECT FARMS

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2005
Publication Date: 1/1/2006
Citation: Small, B.C., Chatakondi, N. 2006. Efficacy of formalin as an egg disinfectant for improving hybrid catfish (ictalurus punctatus x i. furcatus) hatching success. North American Journal of Aquaculture 68:9-13.

Interpretive Summary: A slow economy and foreign fish imports threaten the profitability of US catfish farming. In response, researchers and producers have begun to evaluate the channel catfish female x blue catfish male hybrid as a potential aquaculture candidate. However, hybrid catfish fingerlings are not readily available to farmers at this time because of poor hatching success and fry survival. Research was conducted to determine the most effective means of treating diseases affecting hybrid catfish eggs as a means of improving hatching success and fry survival. After evaluating several disinfecting agents, doses, and treatment methodologies, a recommendation was made for improving hybrid catfish hatching success. Thrice daily treatment of hybrid catfish eggs with 100 ppm formalin as a 15 min bath is recommended. Studies such as this one will lead to improvements in hybrid catfish fry production, which could lead toward to adoption of large-scale hybrid production.

Technical Abstract: Formalin is currently the only aquaculture drug approved by the U.S. Food and Drug Administration for the control of fungi on the eggs of all finfish. The efficacy of formalin for disinfecting hybrid catfish (Ictalurus punctatus x I. furcatus) eggs was examined and initially compared to three other potential chemotherapeutants. Two experiments were conducted to evaluate treatment dose and frequency on hybrid catfish hatching success. In the first experiment, hybrid catfish egg masses were divided and assigned to one of 13 treatments administered as daily 15 min baths. The treatments included: (1) Control (no treatment), (2) 50 ppm formalin (F), (3) 100 ppm F, (4) 200 ppm F, (5) 125 ppm hydrogen peroxide (HP), (6) 250 ppm HP, (7) 500 ppm HP, (8) 50 ppm povidone iodine (PI), (9) 100 ppm PI, (10) 200 ppm PI, (11) 2.5 ppm copper sulfate (CS), (12) 5 ppm CS, and (13) 10 ppm CS. Hatching success tended to be highest among eggs treated with 100 ppm formalin (87.7%), 2.5 ppm copper sulfate (87.0%), or 100 ppm povidone iodine (85.2%), although not significantly (P>0.05) different from the control treatment (82.8%). Treatment with 500 ppm hydrogen peroxide resulted in a significant (P < 0.05) decrease in hatching success (31.5%). In the second experiment, the optimal frequency of formalin treatments was assessed by treating hybrid catfish eggs 0, 2, 3, or 4 times daily. Eggs treated three times daily with 100 ppm formalin had the highest (P < 0.05) percentage of hatched eggs. To maximize hatching success, thrice daily treatment of hybrid catfish eggs with 100 ppm formalin as a 15 min bath is recommended.