Artificial reproduction of the indoor-cultured brackish form of maraena whitefish (Coregonus maraena) under recirculated aquaculture system (RAS) conditions

Can Puntius sophore breed artificially under controlled conditions? Tracing the life cycle of Puntius sophore through artificial captive breeding

The development of new strategies for breeding indigenous fish species is of utmost importance in the wake of unfavorable weather events, as a result of climate change. Therefore, an attempt has been made to achieve artificial breeding of an indigenous barb, Puntius sophore. Two groups of juvenile fish, collected from the wild, were reared till sexual maturation. One group was reared under a natural photothermal regime and the other was reared under strictly controlled conditions with photothermal stimulation till sexual maturation and subsequently, hormonal stimulation with OVAFISH was also done for inducement of spawning. The spawning efficiencies were analyzed and the results in terms of latency period (6.74 Hrs), ovulation rate (92.2 %), fertilization rate (90.6 %), hatching rate (89.9 %), and spawning efficiency coefficient (Se) (0.828) were found better in Puntius sophore reared under the indoor controlled condition with photothermal manipulation and hormone administration compared to the group of fish which was reared under a natural photothermal with a hormonal stimulation. The results of this study demonstrate the captive artificial breeding of Puntius sophore spawners reared under a natural photothermal regime and controlled photothermal regime in indoor conditions. The outcome of the present study can be used for developing key strategies for a climate smart aquaculture for fish farmers.

Effect of temperature and spawning agents on wild female asp (Leuciscus aspius) reproductive efficiency under controlled conditions

Artificial reproduction is a bottleneck to produce stocking material for many species of freshwater fish. One of these species is the asp, Leuciscus aspius. Research in the field of artificial reproduction of this species is very scarce and often incomplete. There are no breeding protocols specifying optimal environmental conditions and hormonal stimulation for many species of rheophilic cyprinids, including asp. Since the number of natural asp populations is constantly decreasing, it is important to support natural stocks by restocking with high quality stocking material. For this reason, optimized protocols are needed to breed this species under controlled conditions to produce stocking material with high biodiversity and good health. Such an approach will make it possible to maintain the population of natural asp at a constant level. The aim of this study was to develop the protocol of asp artificial reproduction using optimized thermal conditions and appropriate hormonal stimulation. In experiment I, the influence of constant temperature (10.0, 12.0 and 14.0 °C) on the effectiveness of artificial reproduction of asp. In experiment II, the effectiveness of asp reproduction was checked after the application of spawning agents: Ovopel, Ovaprim or a combination of these two agents The obtained results indicate that for the final maturation of oocytes (FOM) and artificial reproduction of asp in controlled conditions, water temperatures of 10-12 °C are the most useful. Under these thermal conditions, the highest percentages of female's ovulation and embryo survival, as well as the percentage of hatching, were obtained. Hormone injections are necessary to perform final oocyte maturation (FOM) in female asp in captivity. All spawning agents used were especially useful for artificial reproduction of asp, however, the best values of the studied indices, such as ovulation rate and embryo survival, were obtained after the application of Ovaprim or the combination of Ovopel and Ovaprim in water temperature at a range of 10-12 °C. It was found that the pH of ovarian fluid may be a preliminary indicator of the biological quality of eggs in asps. The optimal pH value is 8.0-8.4. At pH below 7.4, no viable embryos were observed.

Can sympathetic induction be a convenient technique for breeding Amblypharyngodon mola (Hamilton, 1822)?

Mola carplet (Amblypharyngodon mola) is one of the most popular small fish species of the Indian subcontinent. There are limited studies on captive breeding of this species, which is important for aquaculture and the conservation prospects of this species. The conventional induced breeding method using an inducing agent (GnRHa and dopamine antagonist) is one of the most effective and prevalent methods of breeding fish. It is a laborious and time-consuming process, particularly in mass fish breeding and in lieu of that, a less time-consuming method - sympathetic induction of the broodstock, is used in some regions of India, particularly in big carp fish. However, this method has not been reported in commercial-scale breeding of small indigenous fish species. Therefore, an experiment was conducted to compare the spawning efficiency of Amblypharyngodon mola bred by sympathetic induction with the conventional complete induced breeding method. The spawning performance in terms of latency period, relative fecundity, fertilization rate, incubation period, and hatching rates of sympathetically induced Amblypharyngodon mola were compared to completely induced Amblypharyngodon mola brooders. Although the latency period (7.8 hrs), relative fecundity (39 nos./g), fertilization rates (81.61%) and spawning efficiency coefficient (0.681) were better in conventionally induced fish, but lower post-spawning mortality (1.29%) and better hatching rates (86.21%) were observed in sympathetically induced fish. The results indicate that quality offspring of Amblypharyngodon mola could be obtained in terms of survivability through sympathetic breeding. Sympathetic induction breeding could be a cost-effective, convenient, time-saving method of mass-scale breeding and aquaculture of Amblypharyngodon mola.

Effect of anti-adhesive supplement doses on sperm motility characteristics in the European whitefish (Coregonus lavaretus)

Sperm adhering to glass slides is one of the main problems during fish sperm motility analyses with CASA systems. To mitigate this, albumin is the supplement added most frequently to activating solutions. However, there is no data on the use of supplements other than albumin (in various concentrations) in analyses of European whitefish (Coregonus lavaretus) sperm motility. This issue was investigated in the presented research using three anti-adhesive supplements (albumin, casein, Pluronic F-127) that were added to Billard solution (BS: 20 mM Tris, 1 mM CaCl2, 154 mM NaCl, 30 mM glycine at pH 9.0) at different concentrations (0.0; 0.1; 0.2; 0.5; 1.0; 2.0%). It was noted that the addition of the lowest concentration (0.1%) of albumin, casein, or the pluronic to BS had a significant effect on the motility and kinetic parameters of whitefish sperm compared to pure BS. BS supplemented with 0.2-0.5% albumin was the most appropriate variant used for whitefish sperm motility activation in the present experiment. BS supplemented with the pluronic at 1.0-2.0% concentrations resulted in significantly higher values of almost all CASA parameters compared to casein at the same concentrations. Moreover, CASA parameters determined in this variant of the pluronic (1.0-2.0%) were similar to those when BS was supplemented with the same albumin concentrations. This indicated that instead of albumin, the pluronic at higher concentrations in BS might be used to analyze whitefish sperm motility.