Theses and Dissertations

Title: The immune response of channel catfish to infections of Ichthyophthirius multifiliis

Name: Joshi, Minerva

Degree: MS

Chair: Ray Allison


University: Auburn University

Location: Auburn, Alabama

Date: 1966

Pages: 35

Keywords: Channel catfish,parasites, Ichthyophthirius multifiliis,immune response


An investigation was begun on February 12, 1966, to determine the immune response of the 5 to 6-inch channel catfish to infections of Ichthyophthirius multifiliis. The fish were exposed to trophozoites at exposure levels of 0, 10, 30, and 60 per fish, with 10 fish in each aquarium at approximately 70oF. Malachite green was used to eliminate the initial infection, and the experimental fish were subsequently exposed to various challenge levels. It was found that the higher the exposure level, the higher the infection level, and the higher the mortality rate. There was 30 percent mortality in fish that were exposed to 60 trophozoites per fish in comparison to 0 mortality in other treatment levels. The agglutination studies of the sera from treated fish indicated that aggluatinins were present in the sera of treated fish and not in that of control fish. The sera of fish exposed to high levels of parasites had stronger agglutinins than those exposed to lower levels. The fish exposed to 60 trophozoites per fish showed strong agglutinins at a dilution of 1:320. The fish were challenged at various levels of parasites per fish in the aquarium. Almost all of the challenged fish became infected to some degree, however, there was 75 percent mortality in the control fish in comparison to 11.1 percent mortality in the previously infected fish. Fish initially exposed to 10 trophozoites per fish had 11 percent mortality at each level when challenged with 20 and 40 trophozoites. Control fish initially exposed to 20 and 40 trophozoites per fish had 55 and 67 percent mortality, respectively. Fish initially exposed to 30 trophozoites per fish and challenged with 40 and 60 trophozoites per fish shoed 33 and 67 percent mortality respectively. Fish initially infected with 40 and 60 trophozoites per fish had 67 and 78 percent mortality, respectively. Fish exposed to 60 trophozoites per fish and challenged with 100 trophozoites per fish had no mortality as compared with 100 percent mortality in fish initially exposed to 0 trophozoites per fish. The sera from the challenged fish showed stronger agglutinins than did those from fish with only an initial exposure. After the initial observation period of 60 minutes, no change was observed up to 390 minutes, however, the following day the tomites in all dilutions were dead.

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