The purpose of this study was to analyse the influence of water salinity on the incubation of eggs and growth of the larvae of sichel Pelecus cultratus (L.) under controlled conditions. The following water salinity was considered: 3, 6, 9, 12, 15 and 0 ppt for the control. The eggs incubation time depended on the water salinity, lasting from 56.3°D [9 ppt] to 107.7°D [0 ppt]. The higher water salinity, shorter the incubation time. The highest survivability of larvae was obtained in water of the salinity equal 3 ppt and in freshwater, where respectively 87% and 84% of the larvae survived. No hatched larvae were obtained in water of the salinity of 12 and 15 ppt, as all embryos died during the experiment. Larvae were reared up for 21 days. The final body weight, depending on the water salinity, reached from 43.5 mg [9 ppt] to 74.6 mg [3 ppt], at the respective body lengths of 19.3 mm and 23.2 mm. The highest body gains and lengths of larvae were observed in water of the salinity of 3 ppt. The lowest survivability of sichel larvae occurred in water of the salinity 9 ppt, where it was only 53.2%. The survivability of larvae in freshwater and water of the salinity of 3 ppt was quite similar: 96.2% and 95.6% respectively. Water salinity degree of 12 and 15 ppt appeared to be lethal for both embryos and larvae of the sichel.

This study analyzed the influence of temperature on the rearing of sichel Pelecus cultratus larvae under controlled conditions. Five constant temperature regimes were tested: 14°C, 18°C, 22°C, 26°C and 30°C. The larvae were reared for 30 days in aquaria with 50 dm 3 working capacities. The larvae density was 40 individuals/ dm 3 and the fish larvae were fed live artemia nauplii. The assessment of the effect of thermal conditions during the rearing period on fish was based on the final size of fish, increment in the total length, relative growth ratio, survivability and condition (the Fulton index). At the end of the 30-day rearing period, it was determined that the largest larvae had been obtained in the 30°C water (average weight 374.2 mg with average length 43.1 mm). The smallest larvae grew in the coldest water (14°C), where their average weight was 32.2 mg with an average length of 19.4 mm. No negative effect of temperature was observed on the survivability rate of reared larvae, which oscillated around 91 ± 5 %. Sichel larvae are characterized by high tolerance and high survivability when reared in high-temperature water.