The development of pisciculture in inner reservoirs and converting pond pisciculture into industrial basis with high level of intensification cannot be successful without improving general piscicultural, veterinary and sanitary standards in this sphere of agroindustry. Thus studying preventive measures and developing modern measures of helminthosis control for fish industry, especially in period of reformation is topical.

The aims of our research were 1) to study dynamics of carps’ parasitological fauna during the vegetative period of breeding and 2) to study terms of parasites infestation.

The investigation was carried out on the basis of fish site “Voloshki” piscicultural and reclamative station “Oleksandriivska” in 2015-2016. The objects of investigation were such species as lamellar carp and wild carp hybrids which are bred in this farm.

In order to study the dynamics of carps’ parasitological fauna and terms of parasites infestation during breeding period once a month were conducted parasitological autopsy of 300 fries and this year’s specimens according to E. Bykhovska-Pavlovska and K. Sekretariuk.

The greatest extensity and intensity of invasion showed disease-producing factor of philometroidosis – Philometroides lusiana. In July were detected: Ichthyophthirius multifiliis (extensity of invasion – 5-8%, average intensity – 4 parasites), Trichodina epizootica (extensity of invasion – 4-6%, average intensity – 4-8 parasites), Bothriocephalus acheilognathi (extensity of invasion – 8-12%, average intensity – 9-16 parasites). Also it was detected increasing in intensity and extensity of invasion of such disease-producing factor as Dactylogyrus vastator.

In August was detected infectious agent of Argulosys – Argulus foliaceus (extensity of invasion – 14-19%, average intensity – 7-9). Maximum extensity of infestation showed Ichthyophthirius multifiliis (extensity of invasion – 8-16%, average intensity – 8-12), Trichodina acuta (extensity of invasion – 12-16%, average intensity – 13-30) and Bothriocephalus acheilognathi (extensity of invasion – 14-16%, average intensity – 19-28).

In August infestation of fries with these three infectious agents was reached top. At the same time was detected decreasing in extensity and intensity of infestation with Apiocoma piscicola (extensity of invasion – 4-6%, average intensity – 2-6), Dactylogyrus vastator (extensity of invasion – 8-10%, average intensity – 20-40) and Philometroides lusiana (extensity of invasion – 26-28%, average intensity – 6-8) and in ponds № 1 and № 2 with Trichodina epizootica tor (extensity of invasion – 6-8%, average intensity – 4).

In September in ponds № 1 and № 2 was firstly detected Gyrodactylus elegans (extensity of invasion – 6%, average intensity – 10-11). At the same time was detected decreasing of intensity and extensity of all infectious agents.

So terms of first infestation of fries and this year’s specimens with different parasites in ponds corresponds with climatic conditions of the year. It is necessary to note that at first fries and this year’s specimens were infected with epizoic parasites with direct development cycle and later with endoparasites with complex cycle of development.

Intensity of infestation of fries was relatively low: 4-30 specimens for protozoa Ichthyophthirius multifiliis, Trichodina acuta, Trichodina epizootica, Apiocoma piscicola;  10-62 specimens for Gyrodaectylus elegans, Dactylogyrus vastator; 8-28 specimens for Bothriocephalus acheslogna; 3-11specimens for nematodes Philometroides lusiana; 2 specimens for crustaceous Argulus foliaceus.

Taking into consideration results of investigation it is possible to conclude that agents of protozoan diseases Ichthyophthirius multifiliis, Trichodina acuta, Trichodina epizootica, Apiocoma piscicola were detected in negligible quantities and do not cause noticeable pathological influence. But deterioration of environmental conditions and favorable conditions for development can cause their quick reproduction and outbreak of diseases.

During parasitological investigation of breeding system of fish site “Voloshki” were detected nine infectious agents in negligible quantities (Ichthyophthirius multifiliis, Trichodina acuta, Trichodina epizootica, Apiocoma piscicola, Gyrodaectylus elegans, Dactylogyrus vastator, Bothriocephalus acheslogna, Philometroides lusiana, and Argulus foliaceus) and observed their seasonal dynamics. Among detected diseases wide epizooty had philometroidosis; maximum infestation was in July.

Key words: lamellar carp, invasion, parasitological fauna, fries, this year’s specimens, infectiousness, extensity, intensity, parasitological autopsy.