Polydactylus is a genus of threadfin that mainly are native to the Indian, Atlantic and Pacific Oceans, especially in coastal or brackish waters (such as mangrove or estuaries). Some may even enter rivers and a single, P. macrophthalmus, is a freshwater fish from rivers in Borneo. Most species do not surpass 72 cm (2.4 ft) in standard length, but two can reach up to 1.7–2 m (5.6–6.6 ft).