Theses and Dissertations

Title: Some host - parasite relationships between white catfish and Ichtyophtyirium multifiliis

Name: Beckert, Heino

Degree: MS

Chair: Dr. Ray Allison

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1964

Pages: 36

Keywords: White catfish,Ictalurus catus,Ichthyophthirius multifiliis,Host,Parasite.


Some host-parasite relationships between the white catfish, Ictalurus catus, Linnaeus 1756, and Icthyophthirius multifiliis Fouquet 1876, were studied under various conditions in the laboratory. Fingerling white catfish were exposed to the parasite at temperatures of 54, 65, 75, or 85oF. At these temperatures visible infections occurred after 288, 200, 72, and 60 hours, respectively. Initial infection levels of 1 and 10 trophozoites of the parasite per fish did not result in mortalities. Infection levels of 50 or 100 trophozoites per fish resulted in a 33% mortality. No fish survived at infection levels of 500 or 1,000 parasites per fish. Initial infection levels of 0, 1, or 5 trophozoites per fish did not produce an immune reaction when challenged with 200 trophozoites per fish and a heavy infection resulted in all individuals. Initial infection levels of 10, 30, 50, or 100 trophozoites per fish resulted in an immune response in all fish and when challenged with 200 trophozoites per fish no re-infection occurred. Fish initially exposed to 10 trophozoites each did not show an infection when challenged with 10 or 50 trophozoites. When challenged with 30 trophozoites per fish, an infection occurred in 40% of the population and 10 percent of the fish died of ichthyophthiriasis. When challenged with 100 trophozoites per fish, 20% of the fish showed an infection and 17% died of ichthyophthiriasis. White catfish were exposed to the parasite at a temperature of 54oF. After an infection appeared, the fish were treated with malachite green at a concentration of 0.10 ppm which eliminated the infection. Unexposed controls were treated with malachite green and maintained at the same temperature. One-half of the previously exposed fish and one-half of the controls were transferred to a temperature of 78oF. All fish were then challenged with 20 trophozoites per fish. A mild infection occurred in controls and in previously exposed fish at 54oF. At 78oF., all controls showed a heavy infection while the previously exposed fish were immune to the parasite at that temperature and showed no signs of an infection. This shows that at a temperature of 54oF., white catfish were unable to produce an immunity to the parasite while at 78oF., these fish exhibited a definite immune response.

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