Taxonomic evaluations are needed to accurately determine the host selection of fish parasites. The present study is a multidisciplinary research in the field of basic and fish diseases sciences. The description of the hybrid species of Squalius orientalis and Alburnus derjugini and infection of Ligula intestinalis in these hybrid fish were reported for the first time from the Kürtün Dam Lake in northeast Turkey. A total of 450 fish were sampled in March, August, and October in 2020 using gillnets. Detailed morphological characteristics (n = 24) were compared to determine the difference among ancestors and hybrid species. The prevalence of L. intestinalis between the sampling periods and the size groups of fish (0 – 10, 11 – 15, and ≥16 cm in length) were examined. Moreover, the highest prevalence of the parasite was observed in October (78.94 %), with a size range of 0 – 10 cm in length (77.8 %). In addition, the total prevalence of the parasite was 48.44 %. The results revealed that most of the diagnostic metric and meristic features of hybrid fish were ranging between the data of S. orientalis and A. derjugini. According to previous reports, when hybrid individuals were compared with their ancestors in terms of prevalence, hybrid individuals were more susceptible to L. intestinalis infections. This study was unique as it provided the first record of L. intestinalis in a hybrid fish population.

The effects of ceramic balls on live transfer conditions of rainbow trout (Oncorhynchus mykiss, (Walbaum,1792)) were determined by examining ammonia, pH, dissolved oxygen, and temperature of water and gill histology of fish. Salt addition and various pH levels of water were also studied for comparison. The study was designed two different pH levels (high 7.98±0.2 and low 6.01±0.1), salt (6g/L), and ceramic ball (10g/l) addition and fish stock density to be 62.3 kg/m3. The trial tanks were mounted on a vehicle to represent actual transport conditions. Fish were sampled every hour for gill histology. As a results, the lowest ammonia value was determined as 1.98 mg/L in the ceramic ball. The highest ammonia value in the high pH group was 2.83 mg/l. When the gill tissues of the fish were examined, the significant differences observed were oedema and epithelial lifting in the control and high pH groups. Hyperplasia, epithelial lifting, and multiple deformations were observed in all the experimental groups except the ceramic ball group. This study showed that based on the histological results of the gills and the stability of the pH levels of the water and the effect on the reduction of the ammonia value of the water, that the ceramic balls are particularly useful for the transport of live fish.

Türkiye’nin, Doğu Karadeniz Bölgesi’nde bulunan Kürtün Baraj Gölü’nde, Georgian shemaya (Alburnus derjugini), Karadeniz alabalığı (Salmo labrax) ve gökkuşağı alabalığı (Oncorhynchus mykiss) olarak isimlendirilen 3 farklı balık türünden, Ekim 2016 ve Eylül 2017 tarihleri arasında, toplamda 129 örnekleme yapılmıştır. Balıklarda Ligula intestinalis, Paradiplozoon sp., Trichodina sp., Chilodonella cyprini, Vorticella sp., Apiosoma sp., Gyrodactylus sp., Ambiphyra sp., ve Ichthyophthirius multifiliis parazitleri bulunmuştur. Gyrodactylus sp., Trichodina sp., Vorticella sp., ve Apiosoma sp. parazitleri bütün balık gruplarında yaygın olarak gözlemlenmiştir. I. multifiliis sadece yetiştiriciliği yapılan alabalıklardan izole edilirken, baraj gölünde sazan türünden izole edilen Ligula intestinalis’in yetiştiriciliği yapılan türlerde kaydına rastlanılmamıştır.