INFLUENCE OF A DIFFERENT WATER EXCHANGE RATE
ON THE GROWTH OF RAINBOW TROUT (Salmo truta)
Rodne Nastova, Vasil Kostov, Nedeljka Nikolova
University “Ss. Cyril and Methodius” in Skopje, Institute of Animal Science, Bul. Ilinden 92-a, Skopje, Republic of Macedonia
rodne_nastova@yahoo.com
The objective of the experiments which were conducted in the fish ponds of the Bošava fisheries ‑ Kavadarci, R. Macedonia, was to investigate the influence of a different number of water exchanges per day on the growth rate and food conversion. Based on the results obtained the following conclusions can be drawn: 1) The weight growth rate was affected by the quantity of fish in the pond. Most favourable results were achieved with 72 water ex¬changes per day. 2) The length growth rate of fish was also affected by the water flow but far less than the weight growth rate. The differences of the length growth rate of fish reared under the conditions of 40 and 72 water exchanges per day were insignificant. 3) The lowest value of food conversion was obtained with 72 water exchanges per day proving thereby that food was utilized most efficiently under these conditions. Mortality rate was lower and had no effect on the overall fish production.
Keywords: rainbow trout; growth; food conversion; water exchange rate
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