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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #169703
Title: OPTIMIZING CHEMOTHERAPEUTIC TREATMENT OF HYBRID CATFISH EGGS FOR MAXIMAL HATCHING SUCCESS

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

Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: 8/4/2004
Publication Date: 1/20/2005
Citation: Small, B.C., Chatakondi, N. 2005. Optimizing chemotherapeutic treatment of hybrid catfish eggs for maximal hatching success. Aquaculture America Conference.

Interpretive Summary:

Technical Abstract: Fungal and bacterial egg infections can be a significant problem in commercial catfish hatcheries. Dead eggs and other organic matter in hatchery culture systems provide excellent substrates for fungi and bacteria. Without chemotherapeutic treatment, these pathogens can quickly overtake the egg mass and significantly reduce embryo survival. Several chemical therapeutants have been investigated as potential treatments to control fish egg diseases and are currently designated by the U.S. FDA as a approved aquaculture drugs or low regulatory priority aquaculture drugs. We report three studies conducted to identify the chemotherapeutant, respective concentration, and treatment methodology that yields the greatest hybrid catfish (Ictalurus punctatus x I. furcatus) hatching success. In the first study, four egg masses were divided into thirteen equal sub-masses. Each sub-mass was subjected to once daily chemotherapeutic treatment as a 15-min static bath until eyed. The treatments were as follows: (1) Control (no treatment), (2) 125 ppm H2O2, (3) 250 ppm H2O2, (4) 500 ppm H2O2, (5) 50 ppm formalin, (6) 100 ppm formalin, (7) 200 ppm formalin, (8) 50 ppm povidone iodine, (9) 100 ppm povidone iodine, (10) 200 ppm povidone iodine, (11) 2.5 ppm copper sulfate, (12) 5 ppm copper sulfate, and (13) 10 ppm copper sulfate. In the second study, four trials were conducted with four egg masses per trial to determine the optimal frequency of formalin application for maximizing hatching success. Formalin treatments were administered 0, 2, 3, or 4 times daily as a 100 ppm static bath. In the third study, four trials were conducted with four egg masses per trial to determine the effect of withholding treatments during a putative, formalin sensitive, developmental period. Formalin treatments (100 ppm) were administered thrice daily, such that treatments were administered at 42 hours post hatch (control) or withheld from 42-44, 42-46, or 42-48 hours post hatch. Hatching success for each study was calculated as the percentage of eggs hatched. In the first study, hatching success was greatest among eggs treated with 100 ppm formalin, 100 ppm iodine, or 2.5 ppm copper sulfate. In the second study, the optimal frequency of formalin treatments was determined to be thrice daily. In the third study, 42 hours post hatch (28C) was microscopically identified as a putative, formalin sensitive, developmental stage for hybrid catfish, and formalin treatments administered at 42 hours post hatch significantly reduced hatching success. Together, these data identify an optimal chemotherapeutic treatment regime for managing maximal hatching success of hybrid catfish.