The growth of fish in intensive fish farming is carried out completely by the feeds supplied from externally. Different ingredients are used in feed production. The nutritional content of these ingredients is checked when purchased or brought to the factory. These ingredients are then stored until feed production. Storage duration and storage temperatures directly affect the freshness criteria of feed ingredient materials. Especially when high-energy ingredients with high levels of fat are stored in poor storage conditions, the fats in the ingredients are oxidized, therefore the peroxide number increases and the ingredient becomes bitter. Oxidation not only destroys the lipids in fish feeds but also vitamins. Slow growth, poor feed evaluation, color darkening, lethargy and deaths have been reported in fish fed with diets that are oxidized and inadequate in vitamin E. In this study, oxidation levels of fish feed ingredients were determined due to different storage conditions. Generally, the number of peroxides increased due to the increase in storage time and temperature, depending on the type of raw materials and oil content.

Fats have a function in transmitting the necessary fatty acids to fish as well as being an energy source in fish nutrition. In particular, high-chain unsaturated fatty acids are needed for feeding saltwater fish. In this study, the fatty acid composition of fish oils obtained from some whole-body fish and fish by-products used in the fish-feed industry in Turkey was determined and compared with each other. Accordingly, SFA (Saturated fatty acids) ratios were in the range of 15.57-33.38% in the oils obtained from the whole-body fish and in the range of 16.3-31.89% in the oils from fish by-products; MUFA (Monounsaturated fatty acids) ratios were in the range of 24-38.69% in the oils obtained from the whole-body fish and in the range of 25.81-47.57% in the oils from fish by-products; PUFA (Polyunsaturated fatty acids) ratios were in the range of 31-36.73% in the oils obtained from the whole-body fish and in the range of 33.54-36.78% in the oils from fish by-products. Given DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid) ratios which are among the most important PUFAs for nutrition, it was determined that DHA ratios were in the range of 14.08-19.10% in the oils obtained from the whole-body fish and in the range of 3.55-15.28% in the oils from fish by-products, whereas EPA ratios were in the range of 8-9.89% in the oils obtained from the whole-body fish and in the range of 2.63-15.28% in the oils from fish by-products.

Skeletal abnormalities in farmed fish are one of the main problems that negatively affect the production enterprises in terms of economic, biological and animal health. Fish with skeletal deformities in hatcheries are considered as non-economic individuals and are therefore detected and removed manually from the production tanks, which is a time consuming and laborious work for the facilities. Since the formation of abnormalities in the skeletal structure of the fish during the early growth period cause reduced swimming ability or speed that prevent fish to compete during feeding. Further, since deformed fish has no market value, even the share of a small amount of feed among deformed fish will reduce the feed conversion for the market targeted individuals within the culture tank that in terms may increase the production cost per fish. Therefore, in culture conditions it is important to remove the deformed fish from the tank environment by quickly determining those fellows at the early stage of growth. The present study evaluates the effects of water velocity on swimming behavior of juvenile seabass (Dicentrarchus labrax) and provides a solution for a rapid identification -and mechanical removal of deformed fish from the culture environment by using swimming speed slowdown -and behavioral differences as an indicator of deformation.

Tüm dünyada olduğu gibi Türkiye’de de su ürünleri yetiştiriciliği büyük bir hızla gelişmektedir. Türkiye’de yetiştirilen türler arasında alabalık ilk sıralarda yer almaktadır. Genel olarak Türkiye’de alabalık üretimi için ticari yatırımların 1970’li yıllarda başladığı bildirilmişse de aslında ilk deneme üretimlerinin ve göllerde balıklandırma çalışmalarının 1950’li yıllarda gerçekleştirildiği dikkati çekmektedir. Prof. Dr. Curt Kosswig öncülüğünde yapılan ilk denemeler ile Abant gölünde 1954 yılında Salmo trutta abanticus Tortonese 1954, türü alabalık yumurtalarından yavru üretilerek göle balıklandırma yapılmıştır. Daha sonraları alabalık, 1980’li ve 1990’lı yıllarda giderek artan bir ilgiyle üretilmiş ve 2000’li yıllarda sayıları artan balık çiftlikleriyle yetiştiricilik içerisinde büyük önem kazanmıştır. Başlangıçta yurt dışından getirilen gökkuşağı alabalığı yumurtaları ile başlayan üretim, özellikle kuluçkahanelerin sayılarının artması ve modernizasyonu ile gelişmiş ve önemli bir sektör haline gelmiştir. Ayrıca son dönemlerde Türk Somonu adı altında Karadeniz için önemli bir üretim hamlesi ile birlikte ihracat konusunda değerli bir katma değer yaratan ürün haline gelmiştir. Bu çalışma ile önemli bir tür olan alabalık yetiştiriciliğinin Türkiye’deki tarihi gelişimi konusunda bilgiler derlenmiştir.