Dwarf gourami
| Dwarf gourami | |
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| A male (left) and a female (right) specimen | |
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| Genus: | Cuvier, 1831
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| Species: | T. lalius
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| Binomial name | |
| Trichogaster lalius (Hamilton, 1822)
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Dwarf gourami (Trichogaster lalius, formerly known as Colisa lalia) is a South Asian labyrinth fish. Males have an almost translucent blue color, with vertical red to dark orange stripes. In its native range it is dried for food, and it is also kept as an aquarium fish. It has become highly popular for aquaria.
Distribution and habitat
The dwarf gourami originally came from South Asia; it originates from Pakistan, India and Bangladesh. However, it has also been widely distributed outside of its native range.[1] This fish inhabits slow-moving streams, rivulets, and lakes with plenty of vegetation.
Appearance and anatomy
As its name implies, this is a small gourami: at maturity, it will reach an average size of 4 to 5 centimeters (1.5 to 2 inches), though some individuals can grow as large as 8.8 centimeters.[1] Male dwarf gouramis in the wild have diagonal stripes of alternating blue and red colors; females are a silvery color. Besides the difference in color, the sex can be determined by the dorsal fin. The male's dorsal fin is pointed, while the female's is rounded or curved.[2] They carry touch-sensitive cells on their thread-like pelvic fins.[3]Dwarf gouramis sold in fish stores may also be solid colors (e.g., powder blue dwarf gourami or red flame variety).
In the Aquarium
Aquarium requirements
Most dwarf gouramis live for about four years. However, with proper care, they can live longer. Dwarf gouramis are generally peaceful fish, although sometimes they can become aggressive. They do well in most community aquaria. They require a tank that is at least five gallons (ten gallons is much better). They are usually found swimming on the middle to top regions of the aquarium because gouramis are labyrinth fish - they can breathe oxygen from the air through their labyrinth organ if necessary. It is important, therefore that the surface of the water be exposed to fresh air. This is usually accomplished by using a hood that allows air ventilation. If efficient air pumps are used, this is not always needed, since the air pumps will refresh the air above the water.
The aquarium should be heavily planted and have at least part of the surface covered with floating plants. A darker substrate will help show off the gouramis' colors, and peat filtration is recommended. Dwarf gouramis should not be kept with large, aggressive fish, but are compatible with other small, peaceful fish as well as with smaller fellow gouramis. Dwarf gouramis should not be kept in tanks with any breeding fish which provide parental care, such as cichlids, as they will likely badger the timid gourami relentlessly in defense of their young. Dwarf gouramis are so docile that they will allow themselves to be bullied to death rather than fight back. Male Siamese fighting fish may attack dwarf gouramis and should be avoided. The males of larger gouramis species may also bully dwarf gouramis.[3] Despite their shy, and docile nature they are aggressive towards fellow dwarf gourami. Each fish tends to establish a territory, and hiding places are a must. Loud noises often scare them, so the tank should be in a quiet area. Regular water changes are necessary, as this gourami can be susceptible to disease.[3]
Dwarf gouramis are tolerant of fairly high temperature. This can be used to eliminate fish diseases such as ich from the aquarium. Temperatures of 80 °F (27 °C) are easily tolerated.
Dwarf gouramis raised for aquarium trade in Singapore may carry dwarf gourami iridovirus. Recent research has shown that 22% of Singapore Trichogaster lalius carry this virus.[4]
Feeding
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A varied diet is very important to the dwarf gourami, which is an omnivore that prefers both algae-based foods and meaty foods. An algae-based flake food, along with freeze-dried bloodworms, tubifex, and brine shrimp, will provide these fish with proper nutrition.
Breeding
The male builds a floating bubble nest in which the eggs are laid. Unlike other bubble nest builders, males will incorporate bits of plants, twigs, and other debris, which hold the nest together better.Once the nest had been built the male will begin courting the female, usually in the afternoon or evening. He signals his intentions by swimming around the female with flared fins, attempting to draw her to the nest where he will continue his courting display. If the female accepts the male she will begin swimming in circles with the male beneath the bubble nest. When she is ready to spawn she touches the male on either the back or the tail with her mouth. Upon this signal the male will embrace the female, turning her first on her side and finally on her back. At this point the female will release approximately five dozen clear eggs, which are immediately fertilized by the male. Most of the eggs will float up into the bubble nest. Eggs that stray are collected by the male and placed in the nest. Once all the eggs are secured in the nest, the pair will spawn again. If more than one female is present in the breeding tank, the male may spawn with all of them. The spawning sessions will continue for two to four hours, and produce between 300 and 800 eggs. Dwarf gouramis have afecundity of about 600 eggs.[1] Upon completion, the male will place a fine layer of bubbles beneath the eggs, assuring that they remain in the bubble nest.The male will protect the eggs and fry. In 12 to 24 hours the fry will hatch, and continue developing within the protection of the bubble nest. After three days they are sufficiently developed to be free swimming and leave the nest. When the fry are two to three days old the male should also be removed or he may consume the young.
The water level should be reduced to 7–10 cm (6-8 inches) during spawning, and the temperature should be approximately 28-30 °C (82 °F). Vegetation is essential, as males build their bubble nest using plant material, which it binds together with bubbles. Nests are very elaborate and sturdy, reaching several inches across and an inch deep. Limnophila aquatica, Riccia fluitans, Ceratopteris thalictroides, and Vesicularia dubyana, are good choices for the breeding tank. Peat fiber may also be offered as building material.
After spawning the female should be moved to a different tank. The male will now take sole responsibility for the eggs, aggressively defending the nest and surrounding territory. When first hatched, the tiny fry should be fed infusoria, and later, brine shrimp and finely ground flakes.[5] Freeze-dried tablets may also be fed to older fry.
Colour variations
Breeders have created different colour variations, varying degree of red/blue colouring.[3] The powder blue variant is almost entirely bright blue. The reddest variety (flame red) can be confused with the red variety of honey gouramis (Trichogaster chuna). One of the most common color morphs is the turquoise / neon blue, featuring stripes of dark red and bright blue.
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Flame red -
Powder blue -
Turquoise / neon blue
References
- ^ a b Froese, Rainer; Pauly, Daniel (eds.) (2011). "Trichogaster lalius" in FishBase. October 2011 version.
- ^ Ristic, Mihajlo (1973), Sex, Nolit
- ^ a b c d Sanford, Gina (1999). Aquarium Owner's Guide. New York: DK Publishing. ISBN 0-7894-4614-6.
- ^ Clarke, Matt (2006-11-23). "Aquarium trade may have spread gourami virus". Practical Fishkeeping magazine.
- ^ Axelrod, Herbert R. (1996). Exotic Tropical Fishes. T.F.H. Publications. ISBN 0-87666-543-1.
- "Colisa lalia". Integrated Taxonomic Information System. Retrieved 11 March 2006.