ABSTRACT. The profitability of rearing larval asp, Aspius aspius (L.), ide, Leuciscus idus (L.), and dace, Leuciscus leuciscus (L.), was assessed in a system of 12 aquaria with a combined volume of 600 dm 3 .Two feeding variants were used: a) natural feed exclusively; b) natural feed plus formulated feed after seven days of rearing. All rearing variants were profitable and posed relatively low financial risks. The variant in which only natural feed was used was the most profitable. The savings incurred by the addition of formulated feed did not offset the profit lost from lower larval stock survival rates. In light of profitability, the most important aspect of larval rearing was the price of the stocking material, which was 250% higher for asp than for ide or dace. In both feeding variants, asp rearing was the most profitable and the values of the indices used to describe profitability were the best.

The profitability of rearing the rheophilic cyprinid fish species asp, Aspius aspius (L.), and ide, Leuciscus idus (L.), in two independent closed recirculating systems was evaluated. The fish were fed live Artemia nauplii exclusively. The rearing of both species was profitable and the financial risk was relatively low. From the point of view of profitability, the purchase price of stocking material was the most significant factor. The price of juvenile asp was 2.5 times higher than that of ide. Rearing larval asp was the most profitable venture.

Assessment of the economic effectiveness of hormonal stimulation application in reophile cyprinid fish reproduction based on the example of asp Aspius aspius (L.) and ide Leuciscus idus (L.) was the goal of the studies presented in this paper. Three hormonal preparations: Ovopel, Ovaprim and carp pituitary were tested during this study. Economic effectiveness of application of those hormonal preparations for asp and ide reproduction stimulation considering the relative working fertility of asp and ide, effectiveness of the selected hormonal preparations and their price were assessed. The cost of hormonal injection per 1000 spawn grains and per 1000 spawn grains in eyed stage was assumed for the measure of economic effectiveness. In case of both studied species injections with Ovaprim and Ovopel were more economic than stimulation with carp pituitary. This is linked to the high application effectiveness of GnRH analogues with dopamine inhibitors found in controlled reproduction of asp and ide. The effectiveness of those hormonal preparations is confirmed by a high percentage of ovulations as well as the high survival rate of the embryos to the eyed stage.

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In the late 1980s, inland aquaculture in Poland produced about 20 and 4 thousand tonnes of carp and trout, respectively. In 2016, the total volume of the sector's production increased to over 35 thousand tonnes, including 18 and 16 thousand tonnes of the two species and above 1 thousand tonnes of another fish. This constitutes 94% of total catches of inland fish and about 15% including sea fishing. Globally, roughly 50% of seafood supply is produced by aquaculture, and farmed fish production exceeds that of farmed beef. The EU's Blue Growth Strategy identifies aquaculture as a sector which could boost economic growth across Europe.The key challenges in the Polish aquaculture sector is significant production growth to 49 thousand tonnes by 2020 and increasing its competitiveness by using resources more effectively, supporting the market by building distribution chains, improving the quality of products and marketing, as well as increasing contribution to environmental protection.