Potassium iodide (KI) is one of the most important sources of iodine which influences the physiological processes connected with reproduction in aquatic animals. This study evaluated the effects of KI immersion on gonadal development of Australian red claw crayfish (Cherax quadricarinatus (von Martens, 1868)). A total of 90 crayfish (45 male and 45 female) were immersed in different concentration of KI, the concentration composed of different levels and added to the 1 liter of water: T1 (0.0 mL L-1), T2 (0.5 mL L-1), T3 (1.0 mL L-1), T4 (1.5 mL L-1), and T5 (2.0 mL L-1) for 14 days cultured under controlled conditions. At the end of the study, body weight, gonad weight, and gonadosomatic index (GSI) were determined for both male and female crayfish. The results of the study showed that KI immersion did not have significant effect (p > 0.05) on males because their body weight gonad weight, and GSI were comparable among treatments. On the other hand, KI immersion showed significant effect (p < 0.05) on females because treatment T2 showed the highest GSI value measured as 4.78±0.54%, while control treatment only recorded a GSI of 2.63±0.25%. This finding indicates that KI immersion at appropriate concentration may significantly improve ovarian development in female C. quadricarinatus as female GSI recorded was significantly higher than the treatment without KI.
