Fecundity and oocyte diameter of Phoxinellus pseudalepidotus (Teleostei: Cyprinidae), an endemic and endangered species from Mostarsko blato (Neretva river basin, Bosnia and Herzegovina)

Mostarsko Blato is a karst field in western Herzegovina and is a habitat for the endangered fish species Phoxinellus pseudalepidotus (Bogutskaya and Zupančič, 2003). Present data suggest that species is restricted only to wetland of the Mostarsko Blato but it is considered to be distributed more widely in the River Neretva basin. According to IUCN Red List, P. pseudalepidotus is listed as Vulnerable D2 ver. 3.1. The purpose of this study is to analyze fecundity and oocyte diameter of P. pseudalepidotus in the area of Mostarsko Blato. The research was conducted at the area of Mostarsko Blato from January to December 2009. The samples were collected using gill nets, and “krtol”. Males and females were separated based on morphological characteristics of the gonads. Gonads were preserved in formaldehyde solution 4%. The absolute fecundity ranged from 965-4740 oocytes, with the mean value and standard deviation of 2524.7±820.63. The diameter of the oocytes inside the gonads varies. The diameter of oocytes of P. pseudalepidotus was between 10.02 µm and 1367.10 µm. The average diameter of the oocyte of P. pseudalepidotus reaches its maximum in January with a value of 446.59±351.74 µm, while the minimum average size was measured in November with a value of 188.05±138.94 µm. The average diameter of oocytes of P. pseudalepidotus during the spawning period was 315.01±284.16 µm. The type of P. pseudalepidotus spawning was categorized as ‘partial spawning’.