The First Data on the Biology of Anatolichthys meridionalis (Actinopterygii, Aphaniidae): an Endemic and Endangered Fish of Turkey (Dalaman River Basin)

Species belonging to the Aphaniidae, extant as well as fossil, are widel distributed along the late-period Tethys Sea coast lines. Among the mentioned genera, Anatolichthys is the genus that includes the 13 species. Anatolia has been a center in the diversity of Anatolichthys. The study is one of the first studies on the growth of the species. On this occasion, in study, it was aimed to examine the growth parameters of the Anatolichthys meridionalis Akşiray, 1948 population, which is an endemic and endangered species in Anatolia. The population structure of endemic species Anatolichthys meridionalis in Gökpınar Spring (Dalaman River basin-Turkey) (37.34° N, 29.44° E) was studied, using 108 fish in October 2019 and September 2020. The growth and reproductive characteristics of A. meridionalis were examined in the study. Males made up 42.59%, females 57.41% of the population. The length-weight relationship and Von Bertalanffy growth equation were W = 0.0112L(3.4638), R(2) = 0.9793, L(t) = 22.97 (1 – e(–0.0304 (t+2.834))), respectively. Average growth performance and condition factor are calculated as 1.21 and 1.84, respectively. The gonadosomatic index was found in a maximum value (12.742%) in July and a minimum value (0.545%) in January. Reproduction time was found to be in between of July and September. The mean fecundity and mean egg diameter were found as 147.94 ± 28.03 number/individual/year and 1.35 ± 0.04 mm, respectively. The first maturation was found to be at age I. First maturity length (L(m)) was estimated at 23.95 mm for females and 22.04 mm for males. Although the study shows that the species has no problem in finding food and is a population with a wide age range, the presence of invasive species in the habitat, the habitat is directly affected by pollution from agricultural activities, water is drawn by pumps for agricultural activities, and it is narrowly distributed and endangered species, A. meridionalis and its habitat Gökpınar Spring should be protected.