Investigation of some biological characteristics of the Ilgin lake (Ilgin, Konya) population of Gambusia holbrooki, an invasive fish species in Turkey

Gambusia holbrooki (Girard, 1859) belongs to the Poeciliidae family and is known around the world as an invasive species harmful to native species. Its global distribution is largely attributed to its intentional introduction for mosquito control in numerous aquatic habitats. Specimens of G. holbrooki were sampled from the designated area between May 2024 and April 2025 as part of this study This study examined the length–weight relationship and condition factor of G. holbrooki. A total of 318 individuals were captured from the sampling area, consisting of 103 males and 215 females. The means of length, weight and condition factor of the sampled specimens were 5.44±0.87 cm, 1.66±0.86 g, 1.00±0.35, respectively. Analysis of the population structure revealed a male-to-female ratio of 1.00:2.08. In conclusion, this study offers insights into the biology and phenotypic adaptability of the species in diverse inland water bodies.