Crimson-spotted Rainbow Fish Melanotania fluviatilis
A small species that is slender and compressed when young but increasing in depth with age head moderate in size, with a relatively large eye, upper edge of eye is close to upper profile of head. Mouth very oblique, and upper jaw protrudes strongly. Jaw teeth conical to canine-like several rows extending outside of mouth; teeth present on vomer and palatines.
Two dorsal fins are separated by a small gap. First dorsal fin origin closer to snout tip than to caudal base, slightly in front of origin of anal fin. Tail slightly forked, usually with 15 branched rays.
Sexual dimorphism (differences)
Mature males have a higher 1st dorsal fin (it overlaps 2nd dorsal fin when depressed; that of females falls short of 2nd dorsal). In addition, the rear tips of the dorsal and anal fins are pointed in males and rounded in females. Males tend to exhibit brighter body and fin colours particularly during courtship and spawning.
Ground colur silvery on sides, with a greenish iridescence, and whitish on belly and lower portion of head. Most body scales have a dusky brown margin, and there is sometimes a narrow reddish stripe (faint or absent in females) between each row of scales. Fins are mainly clear in juveniles and females but males usually have red spotting on dorsal anal and caudal fins. Courting males usually exhibit a blackish margin on all fins.
Males may reach a length of about 90mm but females are usually under 60-70mm
Crimson – spotted rainbow fish inhabits the inland Murray-Darling system of south Australia, northern Victoria, New South Wales and southern Queensland.
Habitat includes rivers, creeks, drains, billabongs, ponds and reservoirs. Victorian population exist in a marginal habitat situation. Spawning is seasonal at least over the southern part of range. In Victoria it occurs mainly between October and January. Each female lays several eggs a day and these are summarily fertilised by the male. The eggs attach to aquatic plants by means of adhesive threads. Hatching occurs in about one week at 25-29oC. Food includes insects and their aquatic larvae, microcrustaceans and algae. This rainbowfish is an active swimmer that congregates in small to large schools often near the surface.
Rainbows in Dam and ponds
Rainbow are very resilient for ponds and dams especially because they can tolerant a wide range of temperature (between 11 – 25oC). They are excellent addition to the biodiversity of ponds and dams. Because they tend to move around in large schooling groups, they are good sporting fish for other predatory fish.
The large males have the capacity to eat their larvae though and other specie larvae.
They are excellent in keeping mosquito larvae down in back yard ponds.