AUSTRALIAN RAINBOWFISH

Description:

A small rainbowfish, with laterally compressed body. Several geographically isolated populations are found in New Guinea, Northern Territory, northern Queensland. So far, genetic data separate Melanotaenia maccullochi into three groups, Burtons Creek, Etty Bay and Cape York populations. Male specimens of the variety found between Cairns and Innisfail have deep, black, irregular, horizontal stripes along a silver body. The dorsal and anal fins are orange-red with a lower black margin running along the body line. The caudal fin has a fan of orange-red colouration. Females are much less colourful, though some do show a hint of the male's coloration. The Harvey Creek and Cairns Red- Finned varieties are similar.

The variety found in the drainage division of the Jardine River are characterised by a series of fine black stripes on the sides, with black submarginal bands and white to yellowish margins on the dorsal and anal fins. Females generally have the stripes less defined. They are also much smaller than the other varieties, both in length and body depth.

Species Diagnosis: Dorsal spines (total): 5-8; Dorsal soft-rays (total): 7-12; Anal spines: 1-1; Anal soft-rays: 13-19.
Distribution: Australasia; Papua New Guinea (lower and middle sections of the Fly River westward to the Bensbach River) and northeastern Australia (3 separate populations as noted above).

Natural Habitat: benthopelagic; freshwater; pH range: 7.0; dGH range: 10.0; Climate: tropical; 20 - 25°C.  Inhabits lowland swamps and small streams, usually in clear, acidic waters with ample cover in the form of log debris or aquatic vegetation.
Conservation Status: Not in IUCN Red List.

Threats:  Habitat degradation.
Size: Max. size: 6.0 cm SL

Water Requirements: tropical freshwater 20 - 25°C.; pH range: 7.0; dGH range: 10.0;
Tank Habitat: dense planting and logs.
Diet: Omnivorous. Adapts to flakes.

Sexing: Males have a deeper body profile and longer fins. Females tend to grow larger and have more rounded bodies than males.
Reproduction: dioecism, external, non-guarders.

M. maccullochi, Harvey Creek.

Tank Community: The Australian form from Harvey Creek seems adaptable to water conditions from soft to moderately hard, pH adjusted to 70. - 7.4. Makes a good community fish with other rainbows and gudgeons requiring similar water conditions. If kept with  M. praecox the males may display aggression but do no damage in such displays..
Incompatible Species: Large fishes, rainbowfish that prefer alkaline water, Arowanas (Yes, mine swallowed them in one gulp when he grew big enough and decided that his tank mates were food).
Comments:  I have found that in a community tank they shoal with Tetras and dwarf rainbows of a similar size.

The fish from the Jardine River and the Etty Bay populations blue and black.

M. maccullochi, Jardine River                 M. maccullochi, Etty Bay

Black Banded Rainbowfish - Melanotaenia nigrans (Richardson, 1843)

Description: Colourful rainbowfish; deep bodied, with prominent black lateral line stripe. They can be recognised by a more slender body than most other rainbowfishes. This is the type species for Genus Melanotaenia.
Distribution: Melanotaenia nigrans has a discontinuous distribution across northern Australia, from the Kimberley region in Western Australia, across the northern part of the Northern Territory to Cape York Peninsula in northern Queensland, including a number of offshore islands such as Groote Eylandt in the Gulf of Carpentaria and Prince of Wales Island in Torres Strait.
Natural Habitat: benthopelagic; freshwater; brackish; pH range: 5.2 - 5.6; dGH range: 10.0 Melanotaenia nigrans has been found in a variety of freshwater environments
but seem to prefer slow-flowing clear water streams, billabongs, and swamps with abundant aquatic vegetation.
Climate: subtropical; 18 - 24°C. Inhabits rainforest streams, lily lagoons and small streams. Also occurs in larger streams, usually in backwaters or along the shoreline where there is minimal flow and grassy vegetation. Often found in brackish, coastal waters.
Conservation.Status: Not in IUCN Red List. Importance: aquarium: commercial.
Threats: Threatened: commercial over harvesting for aquarium trade; habitat degradation.

Size: Max. size: 10.0 cm TL; may reach a maximum size of 12 cm, but usually less than 7 cm.
Water Requirements: freshwater OR brackish water; pH range: 5.2 - 6.7; dGH range: 10.0; temperature 20°C- - 24°C.  Known in water to 35°C.
Tank Habitat: Well planted, depending on water conditions (brackish or freshwater) to provide adequate hiding places among submerged roots and branches; plant with Java Fern in brackish conditions.

Diet: Feeds mainly on aquatic and terrestrial insects and their larvae, and also filamentous green algae.

Sexing:  Melanotaenia nigrans is sexually dimorphic. In males, the spines of the first dorsal are usually extended and may lie well past the origin of the second dorsal when not erect. The posterior rays of the second dorsal and anal fins are extended caudally and may extend past the origin of the caudal fin. In females, the first dorsal spines are short, not reaching the origin of the second dorsal. The posterior rays of the anal and second dorsal fin are not extended. The spines and outer rays of the ventral fins of some males are also extended and may reach past the vent and the origin of the anal fin. Males larger than females. They can be recognised by a more slender body than most other rainbowfishes and may reach a maximum size of 12 cm, but usually less than 7 cm.
Reproduction: dioecism, external, non-guarders.
Tank Community: species tank is best; community fresh water tanks OK; Keep in shoals of 6 or more.
Incompatible Species: larger fish.

Northern Rainbowfish - Melanotaenia solata (Taylor, 1964) Darwin Rainbowfish, Adelaide River Rainbowfish.  

Description:  a colourful rainbowfish with a red tail; similar to M. splendida rubrostriata but paler in colour, with black and red stripes; some geographic variation exists, with deeper colours in some forms. In specimens from Yirrkala, the dorsal and anal fins are red; the caudal fin yellowish is orange; the pelvic fins are deep red; lower side bluish silvery; scale centres on side generally golden bronze; they form about five longitudinal rows, the lowermost of which is approximately on a level with the ventral surface of the caudal peduncle.

Distribution: Occurs in the north-western Northern Territory from the Fitzroy River to the Adelaide River, just east of Darwin. Confined primarily to Arnhem Land, Northern Territory between the South Alligator and Walker Rivers. Also found on the larger offshore islands of the Gulf of Carpentaria including Groote Eyland and Bickerton Island. This species was common in lowland tributaries and flood plains around submerged vegetation and swamps, of the Adelaide River, Northern Territory, and in associated swamps and tannin rich pools. When viewed from above their deep, red tails flashed like beacons. Also common in the Alligator River, southern Arnhem Land.

Natural Habitat: benthopelagic; freshwater rivers and swamps; pH range: 6.5 - 8.0 Climate: tropical; 22 - 28°C;  hardness not tested, but varies with location and season (as does pH).
Conservation Status: Not in IUCN Red List.
Threats:  Habitat degradation, mining pollution, feral animals (trampling of swamps).
Size: Max. size: 10.0 cm TL; 8.0 cm TL (female).

Habitat & Ecology: A stream dwelling rainbowfish mainly found around sub-surface vegetation, submerged logs, or branches in small tributary streams, but can also occur in swamps and lagoons. Their natural environment is subjected to seasonal variations with water temperature, pH, and hardness levels varying considerably. There is often a large fluctuation in water conditions between the dry and wet seasons. Males are easily distinguished from females by their brighter colours and longer and more elongated dorsal fin rays. Growing to a length of around 10 to 12 cm, males are usually much larger and deeper bodied than females. Spawning occurs from October to December, with females producing between 100 and 200 eggs. Eggs adhere to water plants and hatching occurs around 6 to 10 days. Growth is rapid reaching 2-3 cm in 10 to 12 weeks.

Tank Habitat: large tank with free swimming space, well planted. Water parameters pH 7.0 8.0; dGH 10, temperature 25-27^oC. I found that pH and water hardness was not a concern with M. solata, however the water needed to be well aerated and nitrite free. Cover the tank with a cover plate. An easy to keep fish, needing plenty of room and floating weed cover to overcome timidity.  Keep in shoals of 6+.
Diet: Omnivorous. Small crustaceans and insect larvae, vegetable matter- algae and Duck Weed; will eat flake foods, blood worms and daphnia; adaptable to flakes and granules.

Sexing: Males have a deeper body shape and larger dorsal fins.
Reproduction: Spawns in plant growth.

Water Requirements: freshwater tropical, pH 6.5- 8.0; ? dGH 10.
Tank Community: An active fish; keep in shoals of 6 or more; OK with other rainbows; suitable for community tanks.
Incompatible Species: Larger fish.

Melanotaenia solata

Comments: This was the first Rainbowfish that I kept, with the specimens coming from swamps near the Adelaide River, N.T.  I found that they varied in colour from billabong to billabong, some having a deeper brown to black longitudinal, lateral line stripe running from the eye to the tail and more or less prominent, golden stripes on either side of the lateral line stripe. Others showed variation in the red colouring on the tail, dorsal and anal fins. The waters were usually tannin-rich and deep, with the fish swimming near the surface and among sunken vegetation. They were very active fish, hard to catch in daylight but adapted to aquarium life easily.

I found that small, wild-caught specimens adapted well to an aquarium and showed good colour development as they aged. The tanks were well planted and had leaf cover at the surface, as the fish were easily frightened.

Billabong in Kakadu- a typical habitat for M. Solata.

The taxon, Melanotaenia splendida (Castelnau 1875, 1878) included species that are no longer placed in that taxon (e.g. M. australis, M. duboulayi, M. fluviatilis, M. solata, M. tatei). 

However, while  the name 'splendida' is still widely used to refer to several species that may appear similar, recent DNA studies and some aspects of reproduction habits differ sufficiently for different species status to be given.  Hence M. australis, M. duboulayi, M. fluviatilis, M. solata, M. tatei are removed from the former "splendida complex".

I currently keep M. splendida and the captive bred fish resemble those known as Melanotaenia splendida inornata.  I also keep M. fluviatilis and the two species are distinctly different in appearance.

M. splendida is a variable species, and specimens from different creeks and streams are now being sold in Australia under the name of their place of origin.

Melanotaenia splendida

Description: a small, slightly laterally compressed fish with small head and iridescent, green-blue body colour; silver below, bluish above; faint lines of orange-red spots between the rows of scales; very faint lateral line stripe anteriorly and bluish tail. Dorsal and anal fins edged in blue-black. This fish has been grouped in as a Melanotaenia splendida splendida, but some scientists believe it may be related to a M. fluviatilis.

Distribution: endemic to Australia, in the upper, Fitzroy-Dawson River system, Queensland, which drains a large portion of Central Queensland and empties into the sea at Rockhampton, on the Tropic of Capricorn.

Natural Habitat: benthopelagic; freshwater tropical, inland riverine; 10-30°C. Although found in the tropics, its occurrence in the inland reaches, where it is very cold during winter and at night, means that this species is adapted to long periods of cool temperatures. They regularly endure temperatures around 11C and are able to tolerate very high temperatures as well. They are reputedly are very robust fish.

The  Dawson River Rainbowfish

They are available by this name and make beautiful aquarium fish for unheated conditions in Australian homes. They should be kept so as not to hybridise with other Rainbows, to keep the form pure.

Natural Habitat: benthopelagic; riverine; freshwater rivers and swamps; pH range: 6.5 - 8.0 Climate: tropical; 22 - 28°C;  hardness dGH range 9.0 - 19.0., varies with location and season (as does pH).
Conservation Status: Unknown.
I suspect that the trade offers hybrids of this species under a variety of trade names, including M. splendida.
Threats:  Unknown.
Size: Approx. 6.0 cms.
Water Requirements: Freshwater; Soft and slightly acidic (6.8 - 7.0); adaptable to near neutral water.  Temperature 25- 27^oC.  Good filtration required.
Tank Habitat: Planted tank with open swimming spaces. 

Diet: Small crustaceans and insect larvae; brine shrimp, mosquito larvae, red midge larvae, blood worms and daphnia serve as live foods for captive fish; will eat flake foods, adaptable to flakes and granules. Eats Duck Weed (Lemna minor).

Sexing: Males brighter and deeper bodied; first dorsal fin longer in males and reaches the second dorsal fin- females do not. All fins more colourful in the male, with more pronounced yellow and black chequered pattern.

Reproduction: Spawn in plant growth.
Tank Community: Peaceful, active in shoals. Keep in shoals of 6 or more.
Comments:  Adult males can be aggressive towards other Rainbows. Keep these fish in shoals of 6+ with plant cover.

Considered a difficult fish to keep in water with an elevated temperature, as this species is subject to Epizootic Ulcerative Syndrome or 'red spot' disease.

Melanotaenia tatei (Zietz, 1896, et al) Desert Rainbowfish Syn. Melanotaenia splendida tatei

Description: Large rainbowfish, similar to M. australis but more silvery in colour; some geographic variation exists.

Distribution: inland Northern Territory, Queensland and N. E. South Australia, in permanent waterholes, springs and rivers.

Natural Habitat: benthopelagic; freshwater; pH range: 6.0 - 8.0; dGH range: 10 - 30.0, varies with seasonal rains; climate: tropical; 20^o - 30°C. Night temperatures can drop quite low, to near freezing.
Conservation Status:  Not in IUCN Red List.
Threats: Unknown; may be at risk due to desertification and climate change.
Size: Max. size: 10.0 cm TL
Water Requirements: freshwater, 20^o - 25^oC; pH range 6.0 - 8.0; dGH < 30.0; adaptable to a wide range of conditions due to its habitat being seasonally flooded. Water is usually hard and high pH, varying after heavy rains and floods.

Tank Habitat: a well lit, large tank, tropical, 20^o - 25^oC, hard water, pH above 7.2; well provided with hiding places among logs, plants and pebbles. This species can be kept indoors without heating in the tank in most places in Australia, making it adaptable as an aquarium species for unheated tanks. Cover the tank well, as this fish jumps.

Diet: Omnivorous, opportunistic. Small crustaceans and insect larvae; will eat flake foods, blood worms and daphnia; adaptable to flakes and granules.
Sexing: Males brighter in colour; slender; females deeper bodied.
Reproduction: egg layer, probably scatterers; little biology and ecology is available for this fish.
Tank Community: species tank; keep in shoals of 6 or more.
Incompatible Species:
Comments: An adaptable, shoaling species that is becoming more readily available in Australia from captive fish farmed from stock from the Barcoo. I have found that a surface cover of floating plants (Duck Weed) helped with timid fish.

Melanotaenia trifasciata (Rendahl, 1922) Banded Rainbowfish

Description:  Deep bodied fish with marked longitudinal stripes, wide black lateral line stripe, red fins edged in black and iridescent scales. 

Distribution: Northern Territory and Queensland, Australia.

Natural Habitat: benthopelagic; freshwater; pH range: 7.0 - 8.0; dGH range: 9.0 - 19.0; occurs at temperatures ranging from 22°-30° C. Lives mainly in small streams and waterholes in clear to moderately turbid water. Occurs over rocky or gravel bottoms or in well-vegetated areas, frequently around submerged logs and branches.
Climate: tropical; 25 - 30°C. 
Conservation Status: Unknown.

Threats: Unknown.

Size: Max. size: 11.0 cm SL.
Water Requirements: hard freshwater, tropical, temperature range 25 - 30°C, pH 7.0 - 8.0; dGH range 9.0 - 19.0.

Tank Habitat: gravel substrate and rocks or well planted and landscaped with rocks and branches.  Cover.
Diet: Omnivorous; takes small crustaceans, black worms and flake foods.

Sexing:  Males larger than females, with deeper colours.
Reproduction: Spawns in plant growth.

Tank Community: Keep in shoals of 6 or more.
Incompatible Species:  Unknown.
Comments:  Needs space and cover. Reportedly found associated with Melanotaenia splendida inornata and  Melanotaenia nigrans.

A tank of Wonga River M. trifasciata and the Cato River form at right, shows the variation in this species.

The rare, Cato River form, of M. trifasciata

Melanotaenia trifasciata Cato River is one of the new rainbows being developed in Australia.  It is a very colourful form of the species and will probably be much sort after. It comes from the Cato River near Dhalinbuy, in the Northern Territory and is a tropical species.

The future looks bright for Rainbow enthusiasts in Australia.

Utchee Creek Rainbowfish - Melanotaenia utcheensis (McGuigan 2001)

Description: small, Australian, laterally compressed rainbowfish; deep body body golden olive above, paler below, with silvery blue iridescent scales; has distinctive, bluish, mid-lateral stripe edged in orange/red stripes; four red stripes, 2 above and 2 below the lateral stripe, are prominent in adults. Compared to M. splendida, this species has a somewhat larger eye (indicating its darker, rainforest origins). The species was previously regarded as being a colour variety of either the Regal Rainbowfish, M. trifasciata or the Eastern Rainbowfish, M. splendida splendida. However, following mtDNA sequencing (McGuigan et al, 2000) and morphometric analysis (McGuigan 2001), it was elevated to species status.
Distribution:  limited to the coastal tributaries of the North and South Johnstone Rivers, and to tributaries of the North Johnstone on the Atherton Tableland, Queensland, Australia. Collected from Utchee, Fisher, Rankin and Short Creeks in the North and South Johnstone River catchments in north Queensland.
Natural Habitat: benthopelagic; freshwater; found in sites with moderate to high water flow over cobbles and boulders. Climate: subtropical; 24 - 30°C. The surrounding, natural vegetation was tropical rainforest, but this has been cleared to the stream banks. The waters of Utchee creek are on the coastal plain and grazing and dairying on the Tablelands. The impacts of clearing and agriculture on water quality are...

Given the habitat denudation, this species MUST be protected and conserved.

Melanotaenia utcheensis - photo© Günther Schmida

Conservation Status: Not in IUCN Red List: it must be consider to be vulnerable due to its limited distribution and severe threats. Local groups are lobbying for endangered species status.

Size: Max. size to 6.5 cm SL
Water Requirements: freshwater; temperature ranging from 23-27° C and pH 7.0 respectively.

Threats:  introduced fishes (Tilapia); habitat and water degradation- the habitat environment has been developed for intensive sugarcane and banana growing and grazing, removing the rainforest and affecting the creek.
Tank Habitat: well planted tank, with neutral pH; adapts to pH to 7.4 OK.

Diet:  Small aquatic insects and crustaceans. Adjusts to flake foods.

Sexing:  Females less deep in body shape; body colour golden yellow
Reproduction:   dioecism, external, egg layer: not much is known of the biology of this fish.
Tank Community:  As for other Australian rainbows; with plant cover.
Incompatible Species: Does best in a species only tank as a conservation project.
Comments: Peaceful. Needs conservation and protection. Shoals with other rainbows in captivity and may hybridise.  Breeders should not allow hybrids to develop and displace fish that are true to breed.