Age Structure and Length-Weight Relationship of Non-native Redbelly Tilapia Coptodon zillii (Gervais, 1848) (Cichlidae) in the Pinarbasi Spring Creek (Burdur, Turkey)

Abstract

The redbelly tilapia, Coptodon zillii, is found in more than 56 countries as a native or introduced fish. In Turkey it is a non-native species and it is present with several acclimatised populations. A population of C. zillii, which almost certainly originated from aquarium industry ponds located in the area of Burdur, is well-established in the Pinarbasi Spring Creek (Burdur, Turkey). This paper aims to study the population structure and some growth properties of C. zillii living in Pmarbast Spring Creek. For this purpose, age and sex composition and length-weight relationships were examined and then compared with those reported for other populations. During the study period (from November 2013 to June 2016), a total of six fish species (C. zillii, Oreochromis niloticus. Oxynoemacheilus anatolicus, Gambusia holbrooki, Carassius gibelio, Clarias sp.) were caught by electrofishing. Among all, C. zillii has the highest abundance (54.77%). Totally, 155 specimens of C. zillii, ranging in size from 2.4 to 20.5 cm in total length and from 0.16 to 166.1 g in total weight, were collected. Of all the examined C. zillii, 80 specimens were immature, 44 were female and 31 were male. The overall sex ratio of females to males was 0.7:1. Ages of captured specimens ranged from 0 to IV. The length-weight relationship for all individuals was described by the parameters a = 0.0078 and b = 3.3543.