The investigation of the life-history traits of invasive fish species, Coptodon zillii (Gervais, 1848), from Köyceği̇z lake

Turkey has the high variety of inland fish fauna due to zoogegraphical location and high diversity of aquatic habitats. However, recent studies show that with the addition of more than 25 species, this richness is threatened by invasive species. In order to conserve the diversity of freshwater fish biodiversity, there has to be taken effective struggles againist invasive species in both natural and artificial habitats. The Chiclid species C. zillii introduced into Köyceğiz Lake which is a lagoon-eustary system located in the South Aegean region of Turkey. This species accepted as an invasive fish species. In recent years, this species has been reported to very serious problem in terms of the ecology of the water system and aquatic organism by rapidly spread its exanding, especially in Köyceğiz Lake. Therefore growing and reproduction of C. zillii population in Köyceğiz Lake were examined. Between June 2016- September 2017, 1199 C. zillii specimens were captured monthly periods. During the study fish hooks throw nets, hand nets and beach seine were used. The age of the obtained samples was determined and life span, lenght- weight, age- weight, age- lenght characteristic von Bertalanffy growth model, sexuality rate, condition factor, gonadosomatic and hepatosomatic index were calculated. And breeding season and fecundity values were determined fort he revealing of its reproductive success. The total lenght of the caught specimens ranged from 18.2 to 236 mm and the weight ranged from 0.563 to 246.112 g. The lenght-weight relationship logW=3.2533logTL-19432 for the population, r2=0.9971for the determination coefficent, indicating a positive allometric growth. Age was range between 0 and V for both sexes. According to the obteined data from GSI and gonad development, it was determined that the breeding period of the population is between May and August. Fecundity values indicate that the breeding success is high.