Kissing gourami (Helostoma temminckii), also known as the kissing fish or kisser, is a medium-sized tropical freshwater fish and the sole member of the monotypic labyrinth fish family Helostomatidae. It is native to Mainland Southeast Asia, the Greater Sunda Islands, and nearby smaller islands, and has been introduced outside its native range for aquaculture and the aquarium trade.
Taxonomy and Classification
The kissing gourami belongs to the order Anabantiformes (labyrinth fishes) and is the only species in the family Helostomatidae. Its scientific name, Helostoma temminckii, derives from the Greek elos (stud, nail) and stoma (mouth), referring to its distinctive mouth structure. The species was first described by French zoologist Georges Cuvier in 1829. The specific epithet honors Dutch zoologist Coenraad Jacob Temminck. The genus has always been monotypic, and the family Helostomatidae is considered an ancient lineage that diverged early from other anabantoid groups.
Description
The body is deep and strongly compressed laterally. The long-based dorsal fin (16–18 spinous rays, 13–16 soft rays) and anal fin (13–15 spinous rays, 17–19 soft rays) mirror each other in length. The pectoral fins are large, rounded, and low-slung, while the caudal fin is rounded to concave. The lateral line is divided in two, with 43–48 scales along its length.
The most distinctive feature is the highly protrusible, forward-facing mouth with thick lips lined with horny teeth. Unlike other gourami families, the mouth is terminal rather than superior. Teeth are absent from the premaxilla, dentaries, palatine, and pharynx. The species possesses an additional joint between the jaw and the rest of the skull (intramandibular joint), which increases the angle of jaw opening and allows access to nutrients attached to substrates. H. temminckii is the only species known to use this articulation in this manner.
Kissing gourami reach a maximum total length of approximately 30 cm (12 in). There is no outward sexual dimorphism, making it difficult to distinguish sexes.
Color Morphs
Two primary color morphs exist:
- Greenish-silvery (wild form): Lengthwise spotty stripes on the body, opaque dark brown fins.
- Pink (leucistic form): Rose to orangey-pink body with silvery scales and transparent pinkish fins. This is a result of selective breeding in captivity, not a naturally occurring wild form.
A "balloon" or "dwarf" variety with a shortened, rounder body has also been produced by breeders, though this mutated strain is less hardy and has a shorter lifespan.
Distribution and Habitat
The kissing gourami is native to Cambodia, Indonesia (Kalimantan, Sumatra, Java), Laos, Malaysia (Peninsular Malaysia), Thailand, and Vietnam. Its presence in Myanmar is uncertain. It has been introduced to Brunei, Papua New Guinea, the Philippines, Singapore, and parts of Indonesia outside its native range, as well as to Florida (United States), where introduced populations failed to establish.
The species inhabits shallow, slow-moving, and thickly vegetated backwaters, including floodplain lakes, oxbows, swamps, and peatlands. It is associated with both blackwater habitats (where pH can drop as low as 3.0–4.0) and clearer waters. Many of its habitats are subject to seasonal changes in water volume and chemistry.
Ecology and Behavior
Diet and Feeding
The kissing gourami is an omnivorous microphagic filter-feeder. It primarily grazes on benthic algae and aquatic plants, using its toothed lips to rasp algae from stones and other surfaces. It also consumes insects from the surface and supplements its diet with plankton through filter-feeding using its numerous, well-developed gill rakers. The rasping action, which looks superficially like kissing, is also used by males to challenge the dominance of conspecifics.
"Kissing" Behavior
The species displays a unique behavior in which two individuals approach with jaws fully extended and press their mouths together for several seconds. This "kissing" behavior, which gives the fish its common name, is considered an intraspecific aggressive behavior (mouth fighting) and a ritualized form of aggression related to establishing social dominance and territorial boundaries. It is not a courtship or affectionate behavior.
Communication
Kissing gouramis can communicate using their complex inner ear, which contains a suprabranchial air-breathing chamber capable of modulating sounds through air bubbles. They can also produce sounds by moving their teeth.
Ecosystem Roles
The species serves as a host to certain parasitic algal species that survive under the fish's skin, appearing as dark spots. These algae may receive nutrients required for photosynthesis from the host fish. Individuals with algal parasites are commonly found to be less healthy than non-afflicted individuals.
Reproduction
Kissing gouramis are oviparous, dioecious, and mate through external fertilization. Spawning occurs from May to October in Thailand at the beginning of the rainy season. Adults migrate through rivers to shallow lagoons or flooded forests to spawn. They are open-water egg scatterers; the female lays an average of 1,000 spherical buoyant eggs, which are not guarded by the adults. Eggs hatch after approximately one day, and fry are free-swimming two days thereafter. The species does not exhibit parental care. Sexual maturity is reached at three to five years of age.
Conservation Status
The IUCN Red List classifies Helostoma temminckii as Least Concern (assessed 2019, published 2020). The species is locally and seasonally common throughout its range. While threats include overfishing and pollution, declines are not considered significant. The overall population trend is thought to be stable.
Relationship with Humans
Aquarium Trade
Kissing gouramis are popular aquarium fish, prized for their peculiar "kissing" behavior. Large quantities are exported to Japan, Europe, North America, and Australia. The pink leucistic form is among the most widely traded ornamental fish globally. In the aquarium, they require a minimum tank size of at least 75 gallons (for long-term care), with water temperature between 22–30 °C (72–82 °F), pH of 6.0–8.5, and hardness of 5–30 dGH. They are territorial and can bully or chase tankmates; they may also kill other fish by sucking the mucus off their skin. Their average lifespan in captivity is 5–7 years, though they have been known to live in excess of 20–25 years under optimal conditions.
Food Fish
The kissing gourami is regarded as a food fish in its native range and is sometimes farmed. It is used fresh for steaming, baking, broiling, and pan-frying. Thailand and other Southeast Asian countries commercially breed the species for both the aquarium trade and food consumption.
Invasive Potential
The species has been introduced to several regions outside its native range, including parts of the United States (Florida), where populations failed to establish. It is considered a potentially invasive species in regions where it has been introduced.
