Gonadal and Germ Cells Morphology of Nuchequula gerreoides and Eubleekeria splendens (Leiognathidae) from the Pranburi River Estuary of Thailand

The decorated ponyfish Nuchequula gerreoides and splendid ponyfish Eubleekeria splendens are two abundant leiognathid species in the Pranburi River Estuary, Thailand. However, information about their reproductive activity is still limited, preventing the implementation of effective conservative management. In this study, we investigated the sex ratio and the reproductive characteristics in relation to the size distribution of these polyfish species. Fishes were collected during February to November in 2017. The male to female ratios in N. gerreoides and E. splendens were 1.00 : 5.65 (χ2 = 55.2) and 1.00 : 4.65 (χ2 = 40.0), respectively. These ponyfishes shared similar morphology and histology of the reproductive system. All females were classfied as a juvenile because only undeveloped stage (stage 0) oocytes were found in the ovary. Males below 3.4 cm were all juvenile, but all males above 3.4 cm were mature having spermatogenic cells at spermatogenic stages.