The infestation of pond fish ciliated infusoria
Recently in fish farms of Ukraine, the cases of emergence and spread of protozooses. caused by the ciliated infusoria. The spread of disease contributes to the pollution of waters with organic substances, violation of fish and animal health requirements.
For modern aquaculture is characterized by a sharp deterioration of water quality in ponds. This considerably weakens the body of fish, lowers its resistance to diseases, promotes the accumulation of pathogenic microorganisms, which when tight crop of fish raises the risk of a protozoal disease.
We investigated parasitological situation in feeding and nursery ponds of fisheries Krinichansky. This is a full-cycle farm with a cascading arrangement of ponds. The total area of the ponds is 465 ha. Water is pumped from a selection of water from Dneprodzerzhinsk reservoir and Wet of the river Sura. The objects of fish farming are carp and silver carp, which are grown in polyculture. We used the classical method of complete parasitological dissection of fish ( Bykhovskaya-Pavlovskaya. 1969). When conducting parasitological studies in carp yearlings during the summer period were found several species of ciliated infusoria: Trichodinella epizootica. Trichodi na acuta and Ichthyophthirius multifiliis. Extensionactivity (EI) tradename reached 100 %, the intensity of invasion (AI) – 4,5±1,20 instances on the fish.
The infestation rate Ichthyophthirius were as follows: EI was 40 %, an AI of 4.5±1,20 parasites on fish.
In autumn the young of the year carp in the species composition of the protozoan parasite appeared Trichodi na pediculus. but EI parasites of this genus decreased to 70 %, and the AI remained at the same level of 4.3±0,80 ind./fish. Ichthyophthirius fish during this period was not detected.
In the study of parasitic ciliates from the yearlings of silver carp were found to have the same types as that of the young of the year carp – the genera Trichodi na. Trichodinella and Ichthyophthirius. The extensiveness of invasion by tradename in the summer months has reached 70 %, intensity of infestation – 6,7±1.60 instances of fish; Ichthyophthirius EI was 10 % when the intensity of infection in average 2 of the parasite on the fish.
In autumn the young of the year carp were only found ciliated infusoria of the genus Trichodi na. When EI dropped to 40 %, intensity of infestation also decreased to 3.2±0,90 ind./ fish. The ciliate Ichthyophthirius R. during this period were detected.
Exploring seasonal changes of infection year old carp of the ciliated infusoria, it was found that in spring in fish parasitized ciliated infusoria: Trichodinella epizootica. Trichodi na acuta and Ichthyophthirius multifiliis. The extensiveness of invasion by tradename reached 60 %, intensity of infestation – 6,8±2,0 instances on the fish. The extensiveness of invasion by Ichthyophthirius was 10 %, intensity of infestation was represented by single parasites.
In the summer the year old carp were found to have the same kinds of ciliated infusoria. The infestation rate increased slightly, the EI tradename – to 62.5 %, AI to 8.2±2.30 parasites on fish. The extensiveness of invasion by Ichthyophthirius increased to 25 %, the AI was on average 2.5 per instance per fish. In the autumn the year old carp were found ciliated infusoria only one kind – Trichodi na EI with 75%, the AI is 3.5±0,50 ind./fish.
In the study of seasonal changes of infection year old silver carp ciliated infusoria were obtained the following data: in the spring the fish parasitizing ciliate ciliated Trichodi na acuta and Ichthyophthirius multifiliis. The extensiveness of invasion by tradename reached 75 %, the intensity of infestation was 7.3±1,20 instance on the fish; the EI Ichthyophthirius was 25 %, the AI – 2 – 6 parasites on fish.
In the summer the year old carp were found the same species of parasitic ciliates. The extensiveness of invasion by tradename remained at the same level – 70 %, and the AI almost tripled to 23±5,90 ind./fish. The extensiveness of invasion by Ichthyophthirius dropped to 10 %. In the autumn I year old silver carp were found only ciliated infusoria R. Trichodi na. The extensity of infestation was 60 %, the intensity of invasion was 5.6±1,20 instances on the fish.
Thus, studies have shown that pond fish Krinichansky of fish parasitized ciliated infusoria four types: Trichodinella epizootica. Trichodi na acuta. T. pediculus and Ichthyophthirius multifiliis. Moreover, species composition of trichogin differed by seasons. Quantitatively, the maximum infected fishes of these parasites was noted during the summer period. In the spring and fall infestation of fish with a ciliated infusoria decreased. It is known that the above species of ciliates are not oncospecific for fish, therefore, were detected in all species of farmed fish.
When comparing the contamination of different age groups of fish, it was found that the extensity of infection of ciliated infusoria were higher in yearlings, and the intensity of infestation by these parasites – year old. For juveniles the danger of epizootic in the plan was Ichthyophthirius.