The transportation of rainbow trout in the presence of the anesthetic clove oil was investigated. Before the transportation tests, an acute experiment was conducted to verify that removal of the fish from the water for one minute does not significantly increase the glucose or cortisol concentration of the blood plasma. In the main experiment two different transportation conditions were compared: transport in water only and in water with anesthetic. During transportation without addition of clove oil, blood plasma glucose and cortisol concentrations changed significantly. The concentration of glucose increased from 4.92 mmol/L prior to transportation to 6.16 mmol/L and values similar to the initial ones (4.95 mmol/L) were observed 5 hours after transportation. Concentration of the stress hormone cortisol increased from the initial 37.2 ng/mL to 89.2 ng/mL and returned to a value of 36.1 ng/mL 3 hours post transportation. Respective values of glucose concentration have not changed significantly during transportation in the presence of clove oil (4.3; 4.4; 4.4 mmol/L), whereas those of cortisol showed a slight decrease with the passing of time (28.1; 26.7; 20.18 ng/mL). Results show that transportation stress can significantly be reduced by the use of anesthetics.
Hungarian pond fish production is based on grains, but in the last few years, new ideas and efforts have appeared to intensify carp production technology. The basic objective was to change grain-based feeding to nutritionally complete feeds, which ensure rapid growth and more efficient feed conversion rates. This study aimed to utilise empty ponds during the summer period for carp production. Thus, there is no need for fish producers to catch fish in large ponds at the operating water level to satisfy smaller market demands appearing during the summer.
The other aim was to compare the meat quality of fish raised on traditional and nutritionally complete feed until market size in the last year of production. Fatty acid profile and the levels of saturated, monounsaturated, and polyunsaturated fatty acids in fish fillets were specified, and their ratios were analysed. The result showed that nutritionally complete feed with different fatty acid composition affects the fatty acid composition of carp fillet during the rearing period. Quality of the fillet of carp fed with higher unsaturated fatty acid content became more favourable to the consumers due to health promoting effect of polyunsaturated fatty acids.