Effects of ceramic balls on trout welfare during their live transfer conditions

Abstract

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/m(3). 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.