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ARS Home » Southeast Area » Auburn, Alabama » Aquatic Animal Health Research » Research » Publications at this Location » Publication #277666
Title: Susceptibility of three strains of blue catfish to parasite Ichthyophthirius multifiliis

Author
item Xu, Dehai
item Klesius, Phillip
item Bosworth, Brian
item Chatakondi, Nagaraj

Submitted to: Journal of Fish Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2012
Publication Date: 8/23/2012
Citation: Xu, D., Klesius, P.H., Bosworth, B.G., Chatakondi, N.G. 2012. Susceptibility of three strains of blue catfish to parasite Ichthyophthirius multifiliis. Journal of Fish Diseases. 35(12):887-895.

Interpretive Summary: Ichthyophthirius multifiliis (Ich) is one of the most prevalent protozoan parasites of freshwater fish and causes heavy economic losses in aquaculture. Currently there are no effective chemical treatments available and commercial vaccines for Ich prevention have not yet been developed. Genetic improvement of disease resistance through selective breeding could be an alternative way to minimize the loss due to this parasite. Two trials were conducted using both cohabitation and separate-tank methods to compare the susceptibility of 3 strains of blue catfish (D&B, USDA 101 and USDA 102) to Ich infection. The infection level, survival time-span and mortality were evaluated for 3 strains of blue catfish. When exposed to 1000 theronts fish-1 in cohabitation trial, USDA 102 strain of blue catfish showed significantly lower mortality (78.5%) compared to USDA 101 and D & B strain (92.7% and 100%). In trial II with separate-tank methods, all D & B and USDA 101 blue catfish died; however 42.3% of USDA 102 strain survived the infection when exposed to 1000 theronts per fish. The results indicate that there are differences among strains of blue catfish for susceptibility to Ich and these differences will be useful in development of improved catfish germplasm for commercial aquaculture. The information on the susceptibility of blue catfish to Ich would be helpful to blue catfish culture and the breeding program of catfish hybrids.

Technical Abstract: This study compared the susceptibility of 3 blue catfish (Ictalurus furcatus) strains (D&B, USDA 101 and USDA 102) to the parasite Ichthyopthirius multifiliis (Ich). In Trial I, a cohabitation study (all strains stocked communally) was conducted and fish were exposed to theronts at 0, 200, 1000, 5,000 or 25,000 theronts fish-1, respectively. All fish died when exposed to theronts at 5000 or 25,000 theronts fish-1. When exposed to 1000 theronts fish-1, USDA 102 strain of blue catfish showed significantly lower mortality (78.5%) compared to USDA 101 and D & B strain (92.7% and 100%). In Trial II, the same 3 strains of blue fish were evaluated for their susceptibility to Ich with strains challenged in separate tanks by adding Ich theronts at 0, 200, and 1000 theronts fish-1, respectively. All D & B and USDA 101 blue catfish died; however 42.3% of USDA 102 strain survived the infection when exposed to 1000 theronts per fish. The results indicate that there are differences among strains of blue catfish for susceptibility to Ich and these differences will be useful in development of improved catfish germplasm for commercial aquaculture.