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Summary Five separate experiments were carried out on selected aspects of wild crucian carp controlled reproduction including: (a) spawner handling time after catching, (b) water temperature, (c) type of hormonal stimulation and (d) hormonal treatment procedures. The highest ovulation rates and embryo survival rates were obtained when fish were subjected to hormonal preparations within one to 3 days after capture. Administering the ovulation‐inducing injections at 17, 21 and 25°C, a temperature regime around 21°C can be regarded as the optimum for controlled reproduction of the crucian carp (80% of ovulated females; 87.5% embryonic survival rate; 159 eggs per g of female body weight). Much better results were achieved when injections were applied in two‐stages: 12‐h interval application of the dosing scheme as compared to 6 and 24 h intervals. The highest ovulation rate (~90%) was obtained in the groups stimulated with commercial preparations containing a LHRH analogue and dopamine inhibitor: Ovopel (dose 1.2–2.0 pellet kg−1 BW) and Ovaprim (dose 0.5–0.6 ml kg−1 BW). From the control group (treated with a 0.9% solution of NaCl), no females ovulated. These results are considered significant for aquaculturists engaged in controlled reproduction of crucian carp and other cyprinids.

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Effective and safe rearing of larvae of endangered fishes can be facilitated by using dry food diets being suitable for intensive culture. Accordingly, we tested the efficiency of some feeding protocols containing significantly decreased portion of live food or no life food at all in intensive rearing of crucian carp larvae Carassius carassius (L.) under controlled conditions. Based on 7 days long preliminary experiments, SDS 100 and Classic C22 were selected over Sera micron and Nutra HP 0.3 as potential components of a dry food diet. In accordance with other studies, it was found that neither of the pure dry food and mixed food diets tested proved to be as effective as the Artemia nauplii during the first 21 days of the exogenous feeding. Although, the survival rate of larvae could be maintained at high level in some of the protocols tested, a strong decrease in the growth rate was obvious in all diets containing dry food. It was concluded that crucian carp larvae adapt poorly to commercial dry foods, and thus if large larvae of good fitness are needed (i.e. for stockings to natural habitats) then they should be reared on live food diet.