Therapy. of Major Ectoparasitoses in Grasscarp (ctenopharyngodon Idella) Fry and Fingerlings

Willomitzer J.: Therapy of Major Ectoparasitoses in Grasscarp (Ctenopharyngodon idella ) Fry and Fingerlings. Acta vet., 49, 1980: 279-282. Dipping, short-term and long-term baths in solutions of common substances (potassium permanganate, formaline, common salt) currently recommended for the control of ectoparasites of the genera Chilodonella, Trichodinella and Dactylogyrus in grasscarp fry and fingerlings were tested under laboratory conditions. Dipping into a 1 : 1000 diluted potassium permanganate bath for 45 seconds was 100 per cent effective against Trichodinella spp. Short-term baths in a 1 : 2500 formaline solution for 60 minutes was 100 per cent effective against Chilodonella spp., Trichodinella spp. and Dactylogyrus spp., but 23.3 per cent of the treated fish died. The best results in the control of Chilodonella spp. and Trichodinella spp. in grasscarp fingerlings from the 3rd week after hatching were obtained with long-term baths in a 0.7 per cent solution of common salt for 21 to 24 hours. Chilodonellosis, trichodinellosis, dactylogyrosis, intensity of infection, formaline bath, salt bath. During our previous studies on parasitic diseases of herbivorous fish it became clear that grasscarp (Otenopharyngodon idella ) fry and fingerlings in Czechoslovakia were infected mainly with Chilodonella spp., Trichodinella spp. and Trichodina spp. These parasites attack the fry as early as 1 to 3 weeks after hatching and cause an impairment of the hosts. These infestations are followed by infection with Dactylogyrus spp. (Willomitzer 1980). Antiparasitic dipping baths recommended for the control of the aforementioned parasites were tested on a small number of grasscarp by T'esarcik and Ehl (1968). They found that dipping into a 1 : 1000 diluted permanganate bath for 30 to 45 seconds at 10.5 °C water temperature, pH 6.15, was well tolerated by grasscarp. The same applied to dipping into a 1 : 1000 diluted ammonia or trypaflavine bath for 2.5 minutes at 13°C water temperature. According to Musselius (1962) short-term salt baths for 5 minutes in 5 per cent NaCI caa be used at a water temperature up to 15°C, but are a hazard for herbivorous fish at higher temperatures. T'esarclk and Ehl (1968), in their exploratory experiments with salt baths, recorded an increased respiratory rate and excitation of the experimental fish. They reported good experience with short-term baths in malachite green at the concentration of 1 : 150 000 for 1.5 hours at 12.5 °C water temperature. Bauer et aI. (1963) controlled ectoparasites by long-term baths in 0.6 per cent NaCI for 18 hours. L j ubi m 0 v (1975) developed a method of exact chlorine dosing for the control of chilodonellosis, trichodinosis and costiasis in wintering ponds. The finding in our country of increasing infection of grasscarp fry and fingerlings with ectoparasites of the genera Chilodonella, Trichodinella and Dactylogyrus at the State Fishery, Pohofelice in 1978-1979 prompted us to evaluate under laboratory conditions some of the treatments recommended for the control of these parasites.