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ARS Home » Southeast Area » Stuttgart, Arkansas » Harry K. Dupree Stuttgart National Aquaculture Research Cntr » Research » Publications at this Location » Publication #224850
Title: Elimination of Asian fish tapeworms from grass carp with praziquantel bath treatments: The need for 24 hour exposures

Author
item Mitchell, Andrew
item Darwish, Ahmed

Submitted to: American Fishery Society (Fish Health Section) Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/2/2008
Publication Date: 7/9/2008
Citation: Mitchell, A.J., Darwish, A.M. 2008. Elimination of Asian fish tapeworms from grass carp with praziquantel bath treatments: The need for 24 hour exposures. Proceedings of American Fishery Society: Fish Health Section Annual Meeting.p.34.

Interpretive Summary:

Technical Abstract: Several states require that imported fish be free of the Asian fish tapeworm Bothriocephalus acheilognathi. Praziquantel has been used for several years to treat fish with Asian fish tapeworms but rates and exposure periods necessary to eliminate these tapeworms from infected fish have not been adequately determined. The objective of this study was to determine an effective praziquantel bath treatment that would eliminate all tapeworms from a group of naturally infected grass carp Ctenopharyngodon idella. Infected fish were exposed to 6-h (3, 6, 9, & 12 mg/L), 12-h (0.75, 1.5, 6, & 9 mg/L), and 24-h (1.875, 3.75, 0.75, 1.5, & 3.0 mg/L) praziquantel bath treatments. Fish were also exposed to two sequential 12-h treatments by repeating the initial treatment (0.75 and 1.5 mg/L) 3 d later. Treatments were applied at fish densities of 60 g/L of water under the following water quality parameters: temperature = 22.8 to 23.5°C, chlorides = 45 to 60 mg/L, total ammonia nitrogen = <0.1 mg/L, total hardness = 91.0 to 94.2 mg/L, total alkalinity = 206 to 211 mg/L, and pH = 7.57 to 7.68. Fish were necropsied 72 h after the treatments to determine treatment effectiveness since tapeworm clearance takes at least 48 h. None of the 6-h and 12-h single treatments eliminated tapeworms from grass carp; at least 10% of the treated fish were found with tapeworms. The 1.5 mg/L repeated treatment came close to eliminating tapeworms from the grass carp as only one tapeworm was found in 1 of 30 fish. Only grass carp exposed to 0.75 mg/L praziquantel or higher for 24 h were free of tape worms whereas 69 of 80 control fish were positive for tapeworms. Although this product is effective against tapeworms and some agencies have recommended the use of praziquantel on fish to be shipped into their states, the reader is cautioned concerning its use. Praziquantel is not approved by the U.S. Food and Drug Administration for use as a therapeutant on fishes. At the present time, the use of praziquantel against Asian tapeworms in grass carp can only be authorized if the fish producer has established a client relationship with a veterinarian and an extra-labeled prescription is given by that veterinarian. The fish cannot be consumed as food following treatment. Mention of the product praziquantel is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U. S. Department of Agriculture.