Threadfins

threadfins tropical fish of the family Polynemidae, are so called because the lower part of their pectoral fins consists of very long rays, sometimes longer than the body of the fish. These serve as organs of touch, helping them to detect their prey.

Eleutheronema tetradactylum, a species which has a range from India through SE Asia, may reach a length of over 1.5 m (60"), but is usually much smaller. It is silvery-green above and creamy below. It is a fish of commercial importance in India, and is highly esteemed in Thailand—to be fried, boiled, steamed, roasted, pickled, or dried. The specific name means ‘three-fingered’, referring to the three long rays. Some related species have six or seven, but the one which costs most in Thailand, where it is in demand for some special fish soups, is E. tridactylum, which has three.