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Abstract

A study on Sander lucioperca age classes to assess preference for background color was imagined. Two groups: G1 (92 days old, average weight: 6.2 ±1.6 g) and G2 (461 days and 101.7 ±27.1 g), were continuously observed for 24 hours after one day of acclimation, using 90 fish / group (30 fish / replication / 24 hours), their behavior being recorded with cam-recorders. For the study, the walls and bottom of a rectangular research tank were colored equally in: grey, light and dark blue and green. During the study, were made 216 observations / group (72 observations / replication) and were statistically analyzed using Duncan test, with a confidence level of P˂ 0.05 or lower. Results revealed that a significant number from G1 was located on the green space, in order, preferred background color being: green, grey, dark and light blue. The G2 group expressed also high affinity for the green color (P< 0.001) concluding that, green background can give a safety feeling to the pikeperch, thus, rearing or transport of pikeperch categories in green tanks could have the benefit of stress decreasing and added benefit for this fish species in the aim of advancing the Recirculating Aquaculture Systems.

The contents of artificial and natural radionuclides in tissues of the Percidae fish from the Dnipro Reservoir

“…A near-bottom lifestyle characterizes a common perch, but sometimes it rises to the surface, preys on young fish or catches insects that have fallen into the water. The larvae of dragonflies are included in the diet of large individuals of the common perch (Grozea et al, 2016). The pikeperch belong to the more thermophilic Ponto-Caspian complex; they feed on small objects of the boreal-flat faunistic complex (perch, roach).…”

“…The pikeperch, as active predators, hunt for living organisms and swallow them from their tails. Therefore, the modal size of the victims of these species is 3-6 cm, which is slightly larger than that of the common perch that are more likely ambush predators that swallow their prey from the head (Fortunatova & Popova, 1973;Grozea et al, 2016). The statistics of commercial catches of pikeperch in the Dnipro (Zaporizhzhia) Reservoir in the period 2006-2016 is unstable and characterized by low indicators.…”