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Trigonostigma heteromorpha

Trigonostigma heteromorpha
Harlequin Rasbora
The Harlequin Rasbora a small fish belonging to the Family Cyprinidae, subfamily Rasborinae, which was originally given the scientific name of Rasbora heteromorpha. The specific name heteromorpha, translating from the Greek as "differently shaped", alludes to the fact that the body shape of this species differs from that of other members of the genus Rasbora, and as a consequence of this and assorted other factors (including the difference in breeding technique), the fish was assigned to a new genus, Trigonostigma, and is thus now known to science as Trigonostigma heteromorpha. The common name for this fish, Harlequin Rasbora, alludes to the black triangular patch upon the body, which is reminiscent of the patterns found on the costume of a Harlequin.
The species is a popular aquarium fish, and is perhaps the best known of all the Rasboras. The species has been in circulation among aquarists since 1934
The Harlequin Rasbora is a native of Malaysia, Singapore, Sumatra and southern Thailand. It is an inhabitant of streams and other waterbodies that are located in peat swamp forests

The Harlequin Rasbora is a fish that has an approximately lozenge-shaped body, whose basal colour from the head to the caudal peduncle is an orange-pink, the exact hue varying depending upon such factors as water conditions and the original population from which the fish was obtained. The posterior half of the body is overlaid with a large, roughly triangular black marking, that tapers toward the terminal end of the caudal peduncle, and begins approximately below the midpoint of the attachment of the dorsal fin (commonly called a "black wedge"). In common with all Cyprinids, the articulation of the pectoral and pelvic fins follows a familiar pattern, the pectoral fins being located immediately posterior to the operculum or gill cover, whilst the pelvic fins are located some way further back along the ventral portion of the body, in this case almost directly in a vertical line drawn through the dorsal fin. This relationship between the pectoral and pelvic fins is seen in Characins as well as Cyprinids, and is a feature of all the Ostariophysans (fishes possessing an auxiliary mechanism for detecting sound consisting of a set of internal bones called the Weberian Ossicles).
The dorsal, anal, caudal and pelvic fins are all tinted red, the caudal fin being forked, with the red colour concentrated in the outermost rays, the inner section of the tail fin being more hyaline.

It is possible to confuse this fish with two similar species that were indeed originally considered to be subspecies of T. heteromorpha, namely Trigonostigma espei and Trigonostigma hengeli. These fishes are more slender in body shape than T. heteromorpha, and the black marking, instead of being approximately triangular, has a horizontal stripe which tapers towards the caudal peduncle, and is greatly thickened and extended downwards below the dorsal fin. Due to this fishes with this marking are commonly known as "Lamb Chop Rasboras" due to its perceived resemblance to the butchery cut known as a Lamb Chop.
A fully mature individual Harlequin Rasbora attains a standard length of 2 inches (5 cm).
Males are cited as possessing a slightly larger black body patch than females, with the section adjoining the anal fin being more rounded in males. Ripe females are noticeably fuller in body outline.
The Harlequin Rasbora inhabits streams and other watercourses characterised principally by low mineral content, high concentrations of dissolved humic acids, a consequence of those waters flowing through peat swamp forests. The waterlogged soils of these forests inhibit the complete decay of leaf litter, and result in the formation of peat, which leaches humic acids and related compounds into the watercourses flowing through these forests. The conditions thus resemble those found on a different continent, namely the blackwater habitats of South America, and the water chemistry of the Asian habitats of the Harlequin Rasbora is accordingly similar to that of the Rio Negro.

  蓝三角鱼对水质要求较严,以水温20-26昼夜温差不越过3摄氏度的弱 水为宜,必要时,还要在水中添加一些腐殖酸。