Reproductive biology of the invasive Coptodon zillii in the Shadegan International Wetland, Iran

This study explores the reproductive biology of the redbelly tilapia (Coptodon zillii, Gervais, 1848) in the Shadegan International Wetland, southwest Iran. An acceptable number of samples were examined, revealing significant differences, with males averaging 156.17 mm in total length and 78.19 g in weight, compared to females' 144.23 mm and 63.66 g. The sex ratio was skewed in favor of males. The highest Gonadosomatic Index (GSI) values were recorded in April (4.35) and June (2.76), correlating with the reproductive peak and water temperatures of 25.87°C and 34.06°C, respectively. The absolute fecundity ranged from 1,274 to 8,299 eggs per female, with an average of 3,091.25 eggs in the spring and summer months. This study provides essential baseline data for managing and controlling C. zillii, an invasive species threatening the biodiversity of the Shadegan Wetland.