Common carp (Cyprinus carpio L.) as a cultivated fish species has huge importance all over the world. According to FAO statistics, carp is the third most widely bred freshwater pond fish species; only two other Cyprinids (silver carp and grass carp) are bred in higher amounts. Carp is native all over Asia and in a large part of Europe. As a result of human intervention, at present, carp are widespread all over the world, except for the Arctic region. Carp breeding was launched in the antique period, in the ancient Chinese Empire and the Roman Empire. The presently applied method of breeding of common carp has a long evolution. From the effectiveness point of view, the propagation and early-life nursing are crucial parts of carp production, as they provide seed stocks for the further growing section. Without effective propagation, there is no intensive carp production. Nowadays, more advanced propagation methods are available all over the world; however, in the current review, only the main milestones and production efficiency of the propagation and nursing method used in the ponds of Eastern Central Europe are discussed. In the historical overview of carp reproduction, first the natural reproduction, then the semi-extensive and intensive hatchery propagation are presented and investigated in detail. The analysis focuses on the advantages and disadvantages of the method. In particular, the different important milestones of the advanced hatchery method are shown and explained. The effectiveness is proven even with practical calculations. Not only the reproduction, but the pond nursing method is also presented and discussed, concentrating on the management of evolutionarily adapted natural feeds (Zooplankton) and their effect on the survival of fish larvae.

We examined the effects of different stocking densities on the growth and survival rate of ide ( Leuciscus idus) and barbel ( Barbus barbus ) larvae. The fish were reared for 21 days in RAS. Ide larvae were stocked at four densities (25, 50, 75, and 100 larvae l ⁻¹ ), while for barbel, the effects of two different stocking densities (50, 100 larvae l ⁻¹ ) were examined. At the beginning of the experiments, 9 days post-hatch, total length, and body weight of ide larvae were 10.36 ± 0.36 mm and 2.39 ± 0.51 mg, respectively. The same parameters for the barbel were 13.06 ± 0.92 mm and 10.98 ± 1.77 mg. Initially, the fish were fed with live Artemia nauplii, and then they received dry food. The mean final length and weight of ide larvae (30 days post-hatch) across all treatments were 15.12 ± 1.76 mm and 26.85 ± 7.58 mg, respectively. The average survival rate was 82.7 ± 6.25%. Increasing stocking density did not affect adversely the examined indicators. The mean final weight of barbel larvae across all treatments was 629.3 ± 161.6 mg without a significant difference between the two groups. Significantly higher final length was measured in the 50 larvae l ⁻¹ group (20.04 ± 2.08 mm) compared to that of the 100 larvae l ⁻¹ group (18.83 ± 2.46 mm). High survival rates were recorded for both groups (above 90%) without differences. Pre-nursing of ide and barbel larvae in RAS resulted in perfectly developed offspring with extremely low mortality.

This study evaluates in vivo sperm insemination (SI) in European sea bass (Dicentrarchus labrax) to evaluate its applicability in marine finfish for broodstock management. LHRHa-induced females were inseminated with pooled sperm from selected males at a dose of 1 mL kg⁻¹ body weight 12 hours before expected spawning, while a control group spawned naturally. Both treatments were tested in triplicate tanks. Reproduction and larval rearing parameters, including fertilization rate, hatching success, larval survival, and specific growth rates, showed no statistically detectable differences between the SI and control groups (p > 0.05). Parentage was verified using a dynamic multiplex PCR protocol targeting ten microsatellite loci to distinguish involvement of selected sperm and males stocked for courting in SI treatment. Analysis of 569 offspring from the SI resulted in a 98.28% assignment rate to parental pairs, confirming the high resolution of the genetic marker panel. In three experimental tanks, where males providing pooled sperm and natural courting males coexisted, the inseminated sperm sired 52–57% of the genotyped offspring across replicate tanks, while the two courting males present in each tank accounted for 41–48%. Because the pooled dose was derived from four semen donors whereas only two courting males were present per tank, these group-level proportions do not constitute a per-male performance comparison. The results nevertheless demonstrate for the first time that sperm introduced approximately 12 h before spawning remained fertilization-competent and secured a substantial and reproducible share of paternity, with no statistically detectable differences between groups in embryo development or larval performance in European seabass.

The aim of the study is to determine the inhibitory effect of different protein sources on protease activity of Northern pike, E. lucius, during larval ontogeny. For this purpose, Northern pike were fed from yolk sac absorption until 21 days after hatching (DAH). At that point, larvae were sampled on 7, 14 and 21 DAH days and the activity of enzyme was analyzed in vitro. In the study, two different fish meal, chicken meal, krill meal, corn gluten, soybean protein concentrate, soybean meal and dried distillers grains with solubles were tested. Fish meal-I showed the lowest effect (7.53 %) on 7 DAH larvae. Moreover, chicken meal has the highest inhibitory effect on the proteases in the first week (68.27%). In the following period (DAH 14), although the inhibition ratio dramatically increased in all ingredients, fish meal-I has still the lowest effect on proteolytic activity (55.66%). In the same period, the highest effect was obtained from krill (82.28 %) and chicken meals (86.73 %), respectively. Then, there was no statistical difference between fish meal-I, fish meal-II and corn gluten in the 21 DAH and relatively lower than the others (p>0.05). Additionally, chicken meal again has the highest effect on juveniles with the ratio 89.27 %. As a result, the increase of proteolytic activity was notably increased in 7-14-21 DAH, however, it is concluded that feeding larvae and juveniles with live prey is still suggested to get better result for such a carnivorous species culture.