Osmoregulation performance, condition factor, and gonad maturity of tilapia (Oreochromis niloticus) in Cengklik reservoir, Boyolali

Osmoregulation is a physiological adjustment mechanism of fish to environmental conditions. Fish growth performance will reduce when large amount energy redirected for the osmoregulation process. The purpose this study was determine osmotic work level (OWL), pattern, condition factor (K), gonad maturity stages (GMS) and analyze relationship between OWL with GMS tilapia collected from three floating net cages in Cengklik reservoir, Boyolali. Samples were during March – April 2022 followed by some allometric measurements regression analyses. at ranged 4 10 mOsm/L H2O; they performed hyperosmotic pattern. male female were1,86±0,21 1,89±0,18. both dominated IV fecundity 9408±2092.54 eggs. did not reveal significant effect on factors or (p>0.05). Pearson correlation test showed weak (r = 0,204) -0,001). Therefore, uses less produce good because it has more growth, as indicated high (K>1) domination mature gonads.Keywords: Condition Factor; Gonad Maturity; Cages; Oreochromis niloticus;