Yolk utilization and growth during the early larval life of the Silver Perch, Bidyanus bidyanus (Mitchell, 1838)

The aim of this research was to investigate the yolk sac and oil globule utilization by silver perch (Bidyanus bidyanus) larvae produced from domesticated broodfish. The larvae were kept unfed in the holding tank, sampled, and investigated by image analysis software to determine various characteristics, such as the diameters of ova, water-hardened eggs, yolk-sac, oil globules, and the total length of larvae. The research illustrated that, with the exception of oil globule diameter, all other morphometric parameters were significantly lower (P < 0.05) when compared to the larvae from the wild broodfish. The yolk sac was completely absorbed at 96 h post-hatching (hph) and the oil globule was visible until 240 hph. The larvae exhibited predatory movements and tried to catch rotifer at 4 days post hatching (dph). However, the onset of feeding took place at 5 dph, while 100% of feeding occurred at 6 dph. During the first 96 h (h), larvae grew significantly faster than the next 144 h. Larvae encountered low mortalities (<10%) during the first 96 hph, before increasing significantly in the next 24 h and no unfed larvae survived post 240 h. The results also suggested that the exogenous feed should be available at 96 hph, which is well after the yolk sac is completely depleted. In addition, although most of eggs and larval performance from domesticated broodfish were inferior compared to the wild one, it has larger oil globule that could make longer of its mixed feeding period and therefore could have better in viability

Optimalisation of the Activation Medium and Effect of Inhibiting Activities of Acid Phosphatase, Lactate Dehydrogenase and β-N-Acetylglucosaminidase on the Fertilisation Success of Eurasian Perch (Perca fluviatilis L.)

Although methods for the artificial reproduction of perch have been developed, a lack of information remains regarding the enzymes present in its semen, as well as their role in the fertilisation process. In this study, we first select the optimal activating solution for perch fertilisation and then determine the inhibition effect of enzymes that have already been reported as present in the sperm of teleosts—acid phosphatase (AcP), lactic dehydrogenase (LDH) and β-N-acetylglucosaminidase (β-NAGase)—on the percentage of motile spermatozoa and fertilised eggs. Of the 8 studied activation media, a solution composed of 80 mM NaCl, 20 mM KCl, 10 mM Tris, with pH 8.0 and 206 mOsm/kg proved to be optimal for perch gametes. The addition of ammonium molybdate (AcP inhibitor) caused no significant reduction in the percentage of fertilised eggs. On the other hand, the addition of 0.25 mM gossypol (LDH inhibitor) and 0.125 M acetamide (β-N-acetylglucosaminidase inhibitor) significantly decreased the fertilisation percentage to 41.1% and 52.4%, respectively, in contrast to the control (89.9 %). Both LDH and β-NAGase thus seem to play a very important role in the perch fertilisation process