Analysis of endo- and ectoparasite infection of carps from specialized fish farms of Odessa region

Purpose. Conducting an analysis of parasitic diseases of different age groups of carps grown in specialized fish farms of Odesa region under different forms of ownership for 2014–2023. Methodology. The paper presents the generalized results of studies carried out during planned test catches in specialized fish farms of various forms of ownership located in Odesa region. Parasitological studies were carried out according to the Bykhovska-Pavlovska method. The study included: visual inspection; excision of skin and muscle tissue; microscopy of scrapings from the surface of the body, fins and gills; microscopy of eye lenses; pathological autopsy, search for parasites in the body cavity; compression microscopy of internal organs and muscle tissue; intestinal dissection; gallbladder microscopy; dissection and microscopy of the swim bladder walls. At the same time, the parasitic species were identified, and the extensiveness and intensity of the invasion were calculated. Parasites were identified using identification keys. Findings. The study was conducted by employees of the ichthyopathology laboratory of the Institute of Fisheries of the National Academy of Sciences in laboratory conditions and at sampling sites in the period from 2014 to 2023. The objects of the study were different age groups of common carp (Cyprinus carpio), hybrids of silver and bighead carps (Hypophthalmichthys spp.), grass carp (Ctenopharyngodon idella) and crucian carp. Parasitological analysis showed that carp were most often affected by monogeneans, the prevalence (P) was 50.6% of the studied fish, and infestation intensity (II) was an average of 10 parasites per fish. In addition, a large percentage of infection was caused by ciliates with P of 24% P, II was 9 parasites per fish. Grass carp, in turn, were most affected by ciliates — P 56.3% with an average II — 16 parasites per fish and monogeneans — P 36.4% with an average II — 12 parasites per fish and trematodes — P 25.4% with II 8 parasites per fish. Grass carp was the most affected by crustaceans, the P was 46.6%, and the II was 3 parasites per fish, trematode P 16.6% with an average II of 10 parasites per fish. In Prussian carp, infestation by monogeneans was most often detected, which reached 75% with II — 5 parasites per fish. In the period of 2019-2023, carp was most often affected by monogeneans, where P was 29.3%, and II was 3 parasites per fish, also a high percentage of infection was due to ciliates 24%, II was 6 parasites per fish. Chinese carps, in turn, was most affected by trematodes — P 59.1% at II — 60 parasites per fish. Grass carp was the most affected by diplostoma, where P was 45.5% with an average II of 45 parasites per fish. Crucian carp was most affected by lernea. Based on the analysis of data on parasitic diseases of freshwater fish, it can be concluded that both in the period 2014‒2018 and 2019‒2023, fish were most often affected by monogeneans and infusoria, but in the period 2019‒2023, the infestation of silver and grass carps by diplostomes and postodiplostomes increased significantly. Originality. An analysis of parasitic diseases of carp grown in specialized farms of various forms of ownership, located in the Odesa region for the period of over the past ten years has been presented. The results of these studies can be used for parasitological monitoring of water bodies as well as control of the spread of ecto- and endoparasites. Practical value. The obtained results can be used for a timely understanding of trends in the spread of parasitic diseases and allows using the obtained material for parasitological monitoring of fish farms.