Description of three new species within Scleropages formosus. Phylogenetic analysis of partial mitochondrial sequence variation of the cytochrome b gene was undertaken on several colour varieties of S. formosus and revealed that each colour variant represented a distinct monophyletic entity. Because these results were supported by morphological data, it is concluded that S. formosus is composed of four distinct species, of which three are new to science. Scleropages formosus (Müller & Schlegel, 1844) is restricted to the green variety and is characterised by long maxillaries reaching far behind the eyes (upper jaw length: 106.2-109.2% HL), a low head depth (86.5-101.2% HL), a narrow head width (65.3-74.0% HL), a long pre-pectoral length (25.0-27.2% SL), a short pectoral-pelvic length (27.8-30.4% SL) a short pre-anal length (68.6-72.4% SL) and a short anal fin length (25.9-28.0% SL). Scleropages macrocephalus sp. nov. also known as the Silver variety in the aquarium trade (including those with yellow or grey tails) is characterised by long maxillaries reaching the posterior border of eyes (upper jaw length: 106.3-108.9% HL), a high head depth (106.3-116.0% HL), a broad head width (76.3-82.5% HL), a long pre-pectoral length (25.3-27.4% SL), a long pectoral-pelvic length (31.2-35.3% SL), a long pre-anal length (73.2-77.2% SL) and a short anal fin length (24.7-27.6% SL). Scleropages aureus sp. nov. known as the Red Tail Golden in the aquarium trade is distinguished by short maxillaries never reaching the posterior border of eyes (its length: 99.1-101.8% HL), a high head depth (104.8-110.0% HL), a narrow head width (68.6-73.8% HL), a relative intermediate pre-pectoral length (23.9-24.6% SL), a short pectoral-pelvic length (28.3-30.1% SL), a short pre-anal length (68.9-71.0% SL) and a long anal fin (28.7-29.6% SL). Scleropages legendrei sp. nov. which is known as the Super Red arowana in the aquarium trade is diagnosed by its very short maxillaries only reaching the middle of eyes (its length: 95.9- 97.7% HL), a low head depth (90.1-102.3% HL), a narrow head width (65.9-73.9% HL), a short pre-pectoral length (22.2- 23.4% SL), a short pectoral-pelvic length (28.6-30.6% SL), a short pre-anal length (68.3-72.1% SL) and a short anal fin (25.6-27.9% SL). The occurrence of first generation hybrids specimens was observed in some Indonesian farms mainly between S. legendrei and S. macrocephalus. These specimens are easily distinguished from their parental species by their intermediate morphological and molecular characters.