''Betta balunga'' is a species of

gourami Gouramis, or gouramies , are a group of fresh water, freshwater Anabantiformes, anabantiform fish that comprise the family (biology), family Osphronemidae. The fish are native to Asia—from the Indian Subcontinent to Southeast Asia and northeas ...

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the island of

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

, and whose species name derives from the location where it was first described - the Balung River in

Sabah Sabah () is a States and federal territories of Malaysia, state of Malaysia located in northern Borneo, in the region of East Malaysia. Sabah has land borders with the Malaysian state of Sarawak to the southwest and Indonesia's North Kalima ...

, eastern

Malaysia Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...

. It inhabits forest and

blackwater Blackwater or Black Water may refer to: Health and ecology * Blackwater (coal), liquid waste from coal preparation * Black water (drink), a health drink * Blackwater (waste), wastewater containing feces, urine, and flushwater from flush toilets * ...

streams, and grows to a length of .

Habitat and distribution

The type locality of ''Betta balunga'' corresponds to a locality in

Tawau Division Tawau Division () is one of the five administrative sub-divisions of Sabah, Malaysia. It occupies a total of 14,905 square kilometres or 20% of Sabah's territory. The main towns include the capital of Tawau, Lahad Datu, Kunak and Semporna. Tawau ...

, Sabah State, Malaysian Borneo. Its distribution is currently considered to extend southwards from Tawau as far as the Sebuku and Mahakam watersheds in

Kalimantan Timur East Kalimantan (Indonesian: ) is a province of Indonesia. Its territory comprises the eastern portion of Borneo/Kalimantan. It had a population of about 3.03 million at the 2010 census (within the current boundary),Biro Pusat Statistik, Jakarta ...

(East Kalimantan) province in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

. In Sebuku it has been collected alongside '' B. albimarginata'' from a flowing forest streams in very shallow (depth 5-10 cm) water among marginal plants roots and

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall, or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that has fallen to the ground. This detritus or dead organic material and its constituen ...

. In the Mahakam basin it typically inhabits sluggish, black water streams among submerged marginal vegetation and leaf litter. Specimens from the Mahakam differ from Tawau fish in some meristic counts but Tan and Ng (2005) considered them conspecific with ''B. balunga'' due to a lack of comparative material from the type locality.

Sexual dimorphism

Males have brighter colors, more iridescent scales on the head area, a broader head shape, and more extended fins than females.

Diet

In the wild

In the wild, ''Betta balunga'' has a diet that consists of insects such as ''

Drosophila ''Drosophila'' (), from Ancient Greek δρόσος (''drósos''), meaning "dew", and φίλος (''phílos''), meaning "loving", is a genus of fly, belonging to the family Drosophilidae, whose members are often called "small fruit flies" or p ...

'' spp., zooplankton, and other small, aquatic invertebrates.

In the aquarium

The captive fish will normally accept dried products once they’re recognised as edible, but should be offered plenty of small live or frozen foods such as ''

Daphnia ''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the Order (biology), order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their Saltation (gait), ...

'', ''

Artemia ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp or '' sea monkeys''. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th cent ...

'' or bloodworm regularly to ensure development of optimal colour and condition.

Reproduction and development

''Betta balunga'' is a paternal

mouthbrooder Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a va ...

, which means that the fry are incubated in the male's mouth. The female plays the more active role in initiating courtship and defending the area against intruders. After courting, eggs and milt are released during an "embrace" typical of

gouramis Gouramis, or gouramies , are a group of freshwater anabantiform fish that comprise the family Osphronemidae. The fish are native to Asia—from the Indian Subcontinent to Southeast Asia and northeasterly towards Korea. The name "gourami", of I ...

in which the male wraps his body around that of the female, and several "practice" embraces may be required beforehand. Once spawning begins, eggs are laid in small batches and picked up in the mouth of the female before being spat out into the water for the male to catch. Once the male has all the eggs in his mouth the cycle is repeated until the female is spent of eggs, a process which can take some time. The incubation period is 14 – 21 days at which point the male will begin to release fully-formed, free-swimming fry. The male might swallow or prematurely release the fry when stressed. The fry are large enough to eat motile foods such as microworm and ''

'' nauplii immediately.

References

balunga Fish of Asia Taxa named by Albert William Herre Fish described in 1940 {{Anabantiformes-stub