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发表于 2009-3-20 01:57:55
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来自: 中国北京
Experimental treatments
The search for new chemicals and methods to control Cryptocaryon irritans continues. The following two treatments are presented as examples and are not intended as a comprehensive list.
The effectiveness of fatty acids against Cryptocaryon irritans was examined using the red sea bream Pagrus major (Hirazawa, et al., 2001). Caprylic acid was found to have the strongest antiparasitic effect. The fish were fed caprylic acid at a rate of 75mg/kg of body weight per day. The results indicated that caprylic acid has an antiparasitic effect against Cryptocaryon irritans, reducing the number trophonts on the fish. However, despite the reduced number of Cryptocaryon irritans, all of the test subjects died as a result of the infection.
The Food and Drug Administration (FDA) has classified hydrogen peroxide as a Low Regulatory Priority (LRP) drug for use in controlling fungus on fish and fish eggs. Hydrogen peroxide has been experimentally proven to be effective against Amyloodinium sp., a marine fish ectoparasite. It was used at a dosage of 25ppm for 30 minutes to treat Pacific Threadfin, Polydactylus sexfilis infected with Amyloodinium ocellatum. (Montgomery et al., 1999b). Some species of fish tolerate the treatment well, but others are highly sensitive to the chemical (Noga, 2000). Results may also vary between juvenile and adult fish.
Hydrogen peroxide is effective against other ectoparasites, such as Ambiphrya and Gyrodactylus spp. (Rach et al. 2000). Sodium percarbonate is a compound that releases hydrogen peroxide when dissolved in water. Sodium percarbonate was demonstrated to kill the freshwater ectoparasite, Ichthyophthirius multifiliis, at the theront stage or free-swimming, infective stage (Buchmann, et al., 2002). It is currently used in Denmark with rainbow trout Oncorhynchus mykiss at a concentration of 50-100 mg/L is twice a week without any apparent ill effects on the fish.
If more than 50% of the theronts died the concentration of hydrogen peroxide was recorded as effective (Buchmann, et al., 2002). A dosage of 12.5mg/L at a temperature of 12°C kills theronts within 3 hours. This same dosage was not effective against the tomocysts stage of Ichthyophthirius multifiliis. However, dosages of 12.5 mg/L for 180 min and 62.5 mg/L for 90 min were effective against theronts (Buchmann, et al., 2002).
The life cycle of Ichthyophthirius multifiliis is temperature dependant, so the warmer the water temperature the shorter the duration of the parasites life cycle. At 12°C, the medium time frame for tomocsyts to hatch is 9 days and the attached parasitic stage has a duration of 10-12 days. This means that at 12°C treatment should continue daily for a minimum of three weeks. Caution should be taken when using hydrogen peroxide as accidental spills may have an immediate adverse effect on human skin.
Studies to test the effectiveness and safety of hydrogen peroxide for the treatment of other ectoparasites such as Cryptocaryon irritans are fully warranted (Montgomery-Brock, D. et al., 2000). However, this treatment is considered to be highly experimental, therefore it cannot be recommended. The side effects and survival rate when using hydrogen peroxide may not prove to be acceptable. Protective clothing and safety glasses should be worn when using a dose of 35% and higher. The water temperature should be carefully monitored when treating with hydrogen peroxide, because it becomes more toxic as the temperature rises. At this point, the safety, effectiveness, correct dosage and duration of treatment for this experimental method have not been established.
To be continued
The forth installment in this five part series will cover some alternative methods of combating Cryptocaryon irritans. These will include the use of formaldehyde and malachite green, ultra violet sterilizers, freshwater dips, hypersalinity and the sand removal method. Part four will also cover the use of biological cleaners, antimalaria drugs, raising the water temperature, the so-called "reef safe medications and the use of herbal remedies (i.e. garlic) to control Cryptocaryon irritans.
References
Bartelme, T.D. "Cryptocaryon irritans: An Update on the Scourge of Marine Aquariums, Part One." Freshwater and Marine Aquarium Magazine, February 2001a.
Bartelme, T.D. "Cryptocaryon irritans: An Update on the Scourge of Marine Aquariums, Part Two." Freshwater and Marine Aquarium Magazine, March 2001b.
Bartelme, T. D. "Treating Saltwater Ich without Medication" Tropical Fish Hobbyist, January 2001c.
Buchmann, K. Jensen, P. B. & Kruse, K. D. "Effects of Sodium Percarbonate and Garlic Extract on Ichthyophthirius multifiliis Theronts and Tomocysts: In Vitro Experiments." Department of Veterinary Microbiology, Section of Fish Diseases, Royal Veterinary and Agricultural University, Stigbøjlen 4, DK-1870 Frederiksberg C., Denmark, 2002.
Cardeilhac, P. & Whitaker, B. "Copper Treatments: Uses and Precautions." Veterinary Clinics of North America: Small Animal Practice, 18, 85-88, 1988.
Cheung, P.J., Nigrelli, R.F. & Ruggieri, G.D. "Studies on Cryptocaryonosis in Marine Fish: Effect of Temperature and Salinity on the Reproductive cycle of Cryptocaryon irritans Brown 1951." Journal of Fish Diseases, 2, 93-97, 1979.
Colorni, A. "Aspects of the Biology of Cryptocaryon irritans and Hyposalinity as a Control Measure in Cultured Gilt-Head Sea Bream Sparus aurata." Diseases of Aquatic Organisms. 1, 19-22, 1985.
Evans, D.H. "The Roles of Gill Permeability and Transport Mechanisms in Euryhalinity." Fish Physiology, 10, part B (Hoar, W.S. & Randall, D.J., Eds), pp. 239-283. New York Academic Press. 1984.
Goodlett, R. & Ichinotsubo, L. "Salinity and pH Adjustments for Quarantine Procedures for Marine Teleost Fishes." Drum and Croaker, 28, 23-26, January 1997.
http://www.colszoo.org/internal/drum_croaker/pdf/1997.pdf
Hirazawa, N. Oshima, S-I. Hara, T. Mitsuboshi, T. & Hata, K. "Antiparasitic Effect of Medium-Chain Fatty Acids against the Ciliate Cryptocaryon irritans Infestation in the Red Sea Bream Pagrus major." Aquaculture, 198(3-4), 219-228, 2001.
Montgomery-Brock, D. Sylvester, J.Y. Tamaru, C. S. & Brock, J. "Hydrogen peroxide treatment for Amyloodinium sp. on mullet ( Mugil cephalus) fry." Regional Notes, 11(4), Summer 2000.
http://www.ctsa.org/upload/note/RN_11_4631705490300293193.pdf
Montgomery, D., J. Brock and V.T. Sato. "Using hydrogen peroxide for Pacific threadfin infected by Amyloodinium ocellatum." Regional Notes, 10(2), Winter 1999b.
Noga, E.J. "Fish Disease: Diagnosis and Treatment." Ames, IA: Iowa State University Press, 2000.
Rach, J.J. Gaikowski, M.P. & Ramsay, R.T. "Efficacy of Hydrogen Peroxide to Control Parasitic Infestations on Hatchery-Reared Fish." Journal of Aquatic Animal Health, 12, 267-273, 2000.
Copyrights: Terry D. Bartelme |
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