The threadfin sea catfish (Arius arius), also called the Hamilton's catfish, marine catfish or jella, is a species of sea catfish in the family Ariidae. It was described by Francis Buchanan-Hamilton in 1822, originally under the genus Pimelodus. It is migratory and is found in tropical brackish and marine waters in the Indo-western Pacific region, including Bangladesh, India, Cambodia, Malaysia, the Philippines, Pakistan, Sri Lanka, Myanmar, Hong Kong, Thailand, Singapore, and China. It reaches a maximum standard length of 40 cm (16 in), but more commonly reaches an SL of 15 cm (5.9 in).