Abstract Buško Blato Reservoir, the third largest hydro accumulation in Europe, is situated in the south-eastern part of the karstic Livanjsko Polje Valley. This aquatic ecosystem is distinguished by a very rich ichthyofauna and the presence of four endemic fish species. Numerous studies focus on ichthyological researches of Buško Blato Reservoir. Its ichthyofauna has been exposed to changes in ecological factors, which in turn reflected on the structure and composition of fish populations. The main objective of this paper was to assess the current state and predict future trends in the ichthyofauna structure and dynamics based on the field data and comprehensive analyses of literature data. The results of the research indicated the presence of 11 fish species from four families, which is the largest number of fish species ever recorded in this ecosystem. Sander lucioperca, Lepomis gibbosus, Pseudorasbora parva and Tinca tinca were recorded for the first time in this ecosystem, while some previously recorded species were not found. The results of the analyses clearly indicate the presence of natural interspecific competition and significant level of threats to the endemic fish species caused by human activities.

Tramadol hydrochloride/paracetamol is an opioid that is composed of two different analgesics, tramadol (opioid, 37.5 mg) and paracetamol (non opioid, 325 mg). The study presents first data of tramadol hydrochloride/paracetamol effects on haematological parameters and glucose levels in Wistar rats. Oral administration ad libitum of tramadol hydrochloride/paracetamol was administered during a twenty days period. This research includes two groups of animals. Group I include animals that were administered tramadol hydrochloride/paracetamol daily at dosage of 1.12 g/300 ml and group II that were administered daily at dosage of 1.68 g/300 ml of water. We analayzed 14 haematological parameters and glucose concentration. Significant changes were established for all analyzed parameters. Significantly low numbers of erythrocytes, leukocytes and lymphocytes were observed. Tramadol hydrochloride/paracetamol has an extremely negative effect on haematological parameters in Wistar rats, particularily on the blood coagulation due to the thrombocitopenia, anaemia and weakened immunity. If properly administered, tramadol hydrochloride/paracetamol can be an effective analgesic but at high dosage and over a prolonged period it may cause adverse effects in Wistar rats.

Copper sulfate has been used for many years as an algaecide and parasite treatment. The usage of copper has certain issues as there is a thin line that separates effective treatment levels from overdoses. Copper sulfate can be extremely toxic to fish under certain conditions. This study is focused on the effects of copper sulfate on some blood indices in Oncorhynchus mykiss during a 24 hour period. Our research used one procedure 40 Oncorhynchus mykiss with the average weight of 220 ±10 g. The experimental group had 20 fish that were treated with the blue vitriol (dose of 0,012 g/40l), during a 24 hour period. The control group had 20 fish. The presence of copper in the water leads to the significant increase of erythrocyte, hemoglobin, MCHC and leukocyte levels while the MCV levels were noted to be considerably low. Monocytes, unsegmented and segmented granylocites were significantly increased in the experimental group of fish. Lymphocyte count was considerably reduced in the same group of fish.

Studies based on biochemical and hematological parameters in fish are significant in monitoring of health and early detection of pathological conditions. This research obtained values of serum electrolytes and hematological parameters in crucian carp (n = 15) and common carp (n = 13). Significantly different values of K, Cl and Ca concentration were detected. In serum of common carp there were significantly higher concentration of K and Cl and lower concentration of Ca, compared to the crucian carp. Hematological parameters differ in these two species. In blood of common carp significantly lower PCV, hemoglobin concentration, RBC and MCV and notably higher MCHC and WBC were obtained, compared to crucian carp. This preliminary research is important in establishing referential range of biochemical and hematological parameters in cyprinid fishes.