INFESTATION OF LARNAEA CYPRINACEA (CRUSTACEA: CEPOPODA) IN DIFFERENT CATEGORIES OF COMMON CARP ( CYPRINUS CARPIO ) REARED IN SERBIA

Lernaea cyprinacea in common carp and other warm water fi shes is one of the major problems of aquaculture industry in Serbia. Infestations with Lernaea are most prevalent in the summer months and occur more commonly in stagnant or slow-moving water bodies. Th e optimal temperature range for Lernaea development is 26–28°C. In the present study infection rate of L. cyprinacea in two diff erent categories of fi sh pond cultured common carp was done. Pathological eff ects and control of the disease of infected fi sh were also followed. Fish sampling was done during the summer months of 2014, in 3 common carp fi sh ponds. One hundred twenty fi sh samples were collected from all carp ponds (n=120). Aft er fi sh sampling collected Lernaea were transferred to the laboratory for parasite study. Prevalence of the infection was calculated for two age populations of carps. According to the obtained results, the parasite prevalence were signifi cantly higher in carp fi ngerlings than in older carps (P<0.05). Th e highest numbers of parasites were found on fi ns and skin. Carps fry infestation of Lernaea caused intense infl ammation and ulcers what leading to secondary bacterial and fungal infections. Th ese secondary infections sometimes worsen and kill the fi sh. In carps for consumption L. cyprinacea infestation reduces the meat quality and lessening marketability of fi sh, because infected carps cause disgust of consumers and cannot be recommended for human consumption. Technological measures such as improvement of ambient conditions, adequate feed, optimum stock density, reduction of stress, good water quality and lime addition twice a week in quantity of 50 kg/ha are the most effi cacy in combatting this disease.


INTRODUCTION
Lernaea cyprinacea Linnaeus, 1758 (Crustacea: Copepoda), commonly known as "anchor worm", is an important crustacean parasite of freshwater fi sh that has a wide geographic range. Parasite is widely distributed in Africa, Asia, North America and Europe, and there are reports about incidence of it in fi sh ponds and natural aquatic ecosystems (Demaree, 1967;Dorovskikh, 1993 Barson, 2010). If temperatures fall below 20°C, juvenile Lernaea are unable to complete their development and at 14°C, females will not reproduce. However, adult females can overwinter on the fi sh host, producing eggs when water temperatures warm up in the spring. Lernaea cyprinacea have serious deleterious eff ects on their freshwater fi sh hosts (Hoff man, 1999). Lernaea creates skin damages, reduces growth and osmoregulation ability, and also infl uences behavior and decreases fi sh resistance against stressful condition. Infection by the Lernaea can decrease the marketability of older fi sh intended for consumption. Lerneosis occurs in diff erent age categories of common carp. Th e relationship between the size of cyprinid fi shes and L. cyprinacea infections has been studied by Amin et al., (1973), Dorovskikh, (1993) and Pérez-Bote, (2000).
Th e main goal of the present study was to determine infection rate of L. cyprinacea in two diff erent categories of fi sh pond cultured common carp, i.e., carp fry and carp for consumption. We also aimed to investigate its pathological eff ects, control of the disease and marketability of infected fi sh.

MATERIALS AND METHODS
Th e investigation was carried out during 2014, on 3 common carp fi sh farms in Serbia, Vojvodina province. Fish material included 1-to 4 yr-old pond-cultured common carp (Cyprinus carpio). Sampling at the fi sh farms was conducted out between June and August within the intervals of 7-14 days. One hundred twenty fi sh samples were collected from all carp ponds (n=120). From each pond were collected 20 samples of young (fi ngerlings) and 20 samples of older (for consumption) fi sh. Th e sampling program was done using nets. Th e external body surfaces as well as the gill chamber and mouth cavities of each fi sh were examined for the presence of adult parasite and penetration sites for anchored cepopods were localized. A method used by Barson et al., (2008) was used for L. cyprinacea parasite identifi cation. All live and healthy fi sh were returned to the fi sh pond.
Data analysis was performed to determine signifi cant diff erences in the two age categories of carps. Statistica 12 soft ware and Excel (Microsoft Excel, 2007) were used for data analysis. Post-hoc Duncan tests were used for statistical analysis of diff erences. P ≤ 0.05 was considered statistically signifi cant.

RESULTS AND DISCUSSION
Th e infection parameters (the number of parasitized fi sh and prevalence) obtained of L. cyprinacea infestation on the 3 cyprinid fi sh ponds are given in Table 1. L. cyprinacea prevalence (Tabble 1, Graph 1) were signifi cantly higher in carp fi ngerlings than in older carps which are ready for consumption (P<0.05). Th e highest numbers of parasites were found on fi ns (Figure 1), and skin. L. cyprinacea was not found in the nasal and oral cavities.  Controlling many important parasitic diseases is still far from satisfactory condition, and more supervision is needed. Aquaculture development over recent decades and concerns about the prevalence of parasites have caused experts' more attention to this problem created by parasites and their importance in decreasing aquatic animals reproduction power. In general, the most important common crustacean parasites of fresh water fi shes in Serbia is L. cyprinacea. Lernaea infestations are particularly common in cyprinids, especially in common carp, but also in koi, goldfi sh, and other related carp, altho-ugh numerous other freshwater species are susceptible (Lester and Hayward, 2006). It is oft en present in all categories and species of freshwater fi shes. So, it is necessary to pay attention to the incidence, pathological eff ects and control of this parasite, what is essential for carp aquaculture enhancing. In the present study prevalence was 16.6 % in carp fi ngerling, respectively 5 % in carps for consumption. Th is is because the parasites usually occur more frequently in younger than in older category of common carp, especially when fry are cultured in high stock density with poor body condition (Ćirković and Novakov, 2013). Th e parasite in cyprinid species seems to be mainly located in the fi ns. In the present study, the preferred site was the fi ns what is in accordance with the studies of Amin et al., (1973); Saraiva and Valente, (1988); Sterling et al., (1995); Dorovskikh (1996); Pérez-Bote (2000). Th e pathogenic eff ect comes down to the infl ammation of the aff ected tissue. At the attachment places there is infl ammation and ulcers with narrow white brim. Th ese are the places which may become inhabited by pathogenic bacteria and fungi. Infected fi ngerlings are weak and anaemic (Ćirković and Novakov, 2013). In older caterogy the major problem is marketability of fi sh. Since this parasite is the arthropod that are found on the skin it is easily visible, should be removed before harvesting of fi sh. Otherwise, such carps cause disgust of consumers and cannot be recommended for human consumption. Th e most important is control of disease. In order to prevent the disease it is necessary to rear young fi sh separately from other fi sh categories and prevent weed fi shes which can be source of the infection from entering fi sh pond (Ćirković et l., 2015). Several therapies are available for control of lernaeids; however, options are very limited for food fi sh and pond production (Francis-Floyd and Reed, 2011). Th e most effi cacy measure is application of lime twice a week in concentration of 50 kg/ha. Th e improvement of ambient conditions, adequate feed and optimum stock density deliver best results.

CONCLUSION
Lerneosis is one of the most common diseases in freshwater fi shes. L. cyprinacea prevalence was 16.6 % in carp fi ngerling, respectively 5 % in carps for consumption. Lernea in carp fry cause infl ammation and ulcers at the attachement place which result in offt en pathogenic bacteria and fungi infections. Th e major problem of L. cyprinacea infestation in older cytegory is reducing the quality and lessening marketability of fi sh. Technological measures (optimal density, feeding, reduction of stress, good water quality) and lime addition are key factor in combatting this disease.