Taxonomy & naming
Tominanga aurea was described by the Swiss ichthyologist Maurice Kottelat in 1990, in a paper in Ichthyological Exploration of Freshwaters titled 'Sailfin silversides (Pisces: Telmatherinidae) of Lakes Towuti, Mahalona and Wawontoa (Sulawesi, Indonesia) with descriptions of two new genera and two new species.' That work erected the genus Tominanga and named T. aurea as one of its two species, alongside its only known congener, Tominanga sanguicauda. Eschmeyer's Catalog of Fishes records the valid name as Tominanga aurea Kottelat, 1990; because it was described in Tominanga, where it remains, no parenthetical authority is used.
The genus belongs to the family Telmatherinidae, the sailfin silversides, placed in the order Atheriniformes alongside the true silversides and their kin. The Telmatherinidae are overwhelmingly a Sulawesi affair: most of the family's species are confined to the Malili Lakes system, where the genera Telmatherina, Paratherina and Tominanga together form one of the most concentrated radiations of freshwater fishes anywhere on Earth. T. aurea is told apart from its sole congener T. sanguicauda chiefly by a higher gill-raker count — 31 to 36 rakers on the first gill arch, against 27 to 31 in T. sanguicauda — and by details of live-male coloration.
The genus name Tominanga derives from the Tominanga River in Sulawesi, the watercourse that connects Lake Towuti to Lake Mahalona within the Malili system. The specific epithet aurea is Latin for 'golden,' a reference to the yellow-gold coloration that displaying males can show across the body and fins.
Morphology
Tominanga aurea is a small fish, reaching about 2 in in standard length. It has the slender, silvery, somewhat translucent build typical of the sailfin silversides, with the family's characteristic two dorsal fins and a body adapted to life in the open and marginal waters of clear ancient lakes. FishBase records a total of nine to ten soft dorsal rays.
The most useful identifying characters are the gill-raker count and the coloration of mature males. Females and non-displaying fish are plain and silvery; live males show a silvery body marked with yellow or red spots, while the caudal, dorsal, anal and pelvic fins may be plain red or yellow, or hyaline (clear) and dotted with yellow or red. That combination — golden-to-red dotting on a silver ground, with variably coloured median and pelvic fins — separates the species from T. sanguicauda, whose live-male pattern differs. Much of telmatherinid identification rests on the colour and behaviour of breeding males rather than on hard skeletal characters.
No published data are available on maximum age, and growth and life-history details remain sparse. As with many small Sulawesi endemics, what is firmly documented is largely the meristic and colour information from the original description and later compilations.
Habitat
Tominanga aurea is endemic to the Malili Lakes ecoregion on the south-eastern peninsula of Sulawesi, Indonesia — a montane freshwater system that drains southward to the Gulf of Bone and the Banda Sea. The original 1990 description drew on populations from Lakes Towuti, Mahalona and Wawontoa, while FishBase associates the species particularly with Lake Mahalona. Mahalona is the smallest of the major Malili lakes, lying between the very deep Lake Matano and the large Lake Towuti, and linked to Towuti by the Tominanga River for which the genus is named.
The Malili Lakes are an ancient system, on the order of a million years old, and were historically ultra-oligotrophic — exceptionally clear and nutrient-poor. Field accounts of Lake Mahalona describe shallow-water zones vegetated with the endemic aquatic plant Ottelia mesenterium, found only in Matano, Towuti and Mahalona, together with stands of Limnophila aromatica. The Tominanga River runs through seasonal rapids and, near its mouth and in the lake, harbours saltwater crocodiles — these are wild, lightly disturbed waters, not placid ponds.
FishBase characterises the species' environment as tropical, pelagic, and tolerant of fresh and brackish conditions, consistent with a fish that ranges through the open and marginal waters of a large ancient lake. Precise in-situ measurements of temperature, pH and hardness for this species are not well documented in the accessible literature, so the habitat picture is qualitative rather than a set of firm numbers.
Feeding
Direct dietary studies of Tominanga aurea are lacking, but FishBase places the species at an estimated trophic level of roughly 3.1, the value expected of a small, generalist micropredator. In the ancient, historically nutrient-poor waters of the Malili Lakes, a fish of this size and build would be expected to feed largely on small invertebrates — zooplankton, insect larvae, and other small prey taken from the water column and from among marginal vegetation.
The sailfin silversides are active, visually oriented feeders of clear water, and a slender open-water species like T. aurea is well suited to picking small drifting and swimming prey. Beyond that inference, specific feeding observations are sparse, and the diet is best described as that of a small invertebrate-feeder rather than pinned to particular prey items.
Mating
As with most sailfin silversides, the breeding biology of Tominanga aurea shows up most visibly in the colour and behaviour of mature males. The species is clearly dichromatic: males in breeding condition flush with the yellow-to-red spotting and coloured fins described in the original account, while females stay plain and silvery. In telmatherinids generally, males put these colours to work in display and courtship, and the jostling among males to court females is a prominent feature of life in the Malili lakes, where related Telmatherina species are well known for their conspicuous male display.
Specific courtship observations for T. aurea itself are not documented in the accessible literature, so the detailed mating sequence — display posture, pair formation, spawning site selection — is inferred from the family rather than recorded for this species. What is firmly established is that male coloration is the key signalling trait and the basis on which the species was distinguished from its congener.
Breeding
No published data describe the reproductive output, egg type, or development of Tominanga aurea: FishBase carries no maturity, fecundity or age information for the species. Within the sailfin silversides, reproduction generally involves laying adhesive eggs among vegetation or other substrate, with no parental care, and a small lake-dweller of this kind would be expected to spawn a few eggs at a time over an extended period rather than in large single clutches.
Beyond that family-level expectation, the breeding biology of T. aurea is genuinely data-sparse. It should not be confused with documented accounts of better-studied Malili endemics; the honest position is that the specifics of spawning, incubation and fry development for this particular species remain undescribed in the sources available.
In the aquarium
Tominanga aurea is essentially a fish of scientific and conservation interest rather than an aquarium staple, and it does not appear in the ornamental trade in any meaningful way. There is no established body of hobbyist husbandry for the species, and what guidance can be offered comes by analogy with the better-known Sulawesi sailfin silversides and the conditions of its home waters.
The Malili Lakes are clear, warm, historically very pure ancient-lake waters, so keeping Sulawesi telmatherinids well comes down to stable, clean, well-oxygenated conditions, strong filtration, and a long open swimming lane for an active, shoaling open-water fish. A biotope-minded aquarist working from Lake Mahalona field notes might reach for the endemic vegetation — Ottelia mesenterium and Limnophila aromatica — for aquascaping context. But T. aurea is not a fish the hobby keeps, and no reliable captive-care record exists for it. Given its restricted range and Near Threatened status, it is better understood and protected in the wild than sought for the home tank.
Conservation
The IUCN Red List assesses Tominanga aurea as Near Threatened (NT), under criteria reflecting a very small range combined with continuing decline in habitat quality. The species is endemic to the Malili Lakes — a single, isolated cluster of ancient lakes, with nowhere for its endemics to retreat to.
The pressures on that system are well documented. Non-native cichlids ('flowerhorns') have spread from Lake Matano into Mahalona and Towuti, and invasive sailfin armoured catfishes (Pterygoplichthys, the local 'sapu-sapu') drive siltation and algal growth. The invasive aquatic plant Hydrilla verticillata is displacing the endemic Ottelia mesenterium of the lakes' shallow zones. On top of the biological invasions, the catchment is stressed by pollution from household sewage and from nickel mining above Matano and Mahalona, by deforestation and erosion, and by the loss of natural water-level fluctuation through hydro and mining operations.
Observers have noted that fast-swimming, small-egged fishes such as the sailfin silversides and ricefishes may be less directly affected by predatory invasive cichlids than other lake fauna. That is only partial reassurance: the broader decline in water quality and habitat structure still erodes the environment T. aurea depends on. Its narrow endemism within a single threatened lake system is the core concern, which makes the health of the Malili Lakes as a whole the decisive factor in its future.