Distribution and growth of Nga Myin Yinn, Silonia silondia (Actinopterygii: Siluriformes: Schilbeidae), in the Ayeyarwady River, Myanmar

The silond catfish, Silonia silondia (Hamilton, 1822), known locally as Nga Myin Yinn, is rare in Myanmar fish markets and can fetch a high price. Efforts are being made to increase the production for domestic demand. We examined the distribution and growth of S. silondia based on catches in the Ayeyarwady River and growth records in fish farms near the river. The smaller fish were observed downstream near their nursery and the medium fish were around 1 m total length (TL) were often widespread, whereas the larger fish preferred upstream locations. Estimating the individual age from poorly defined periodic rings on the surface of otolith sections was difficult, but their microchemistry may reflect a shared nursery environment and subsequent migration throughout the entire river region. The growth curve estimates in the farmed population revealed a mean TL of 60 cm at four years, indicating that farmed fish were smaller than commercially captured wild fish. This is one of the first comprehensive studies of the river region, but more detailed surveys are needed to manage the fish resource sustainably.