Morphological Changes and Larval Development in Sterlet Sturgeon (Acipenser ruthenus)

This study was carried out to find developing stages of Sterlet sturgeon (Acipenser ruthenus) during the daily sampling from hatching to 20 days post hatch (DPH). Samples were fixed in formaldehyde and measurements were carried out by a loop equipped with a micrometer. In this study, with increasing the age, all organs increased in sizes except in yolk sac volume which was decreased by increasing the age and absorbed in 10 DPH with mean total length (TL) of 19 mm. Melanin plug concentrated in last part of the digestive tract in 1 DPH larvae with mean TL of 8.2 mm, and in 4 DPH with 12.6 mm TL, started to excreted while in 7 DPH (16 mm TL) completely excreted with the opening of the anal. According to the results, for increasing the growth rate and resistance of larvae, it is recommended that to start the feeding of Sterlet sturgeon from 7 DPH.