Taxonomy & naming
Melanotaenia naramasae was described in 2015 by Kadarusman, Nugraha and Pouyaud as part of a major systematic study of the rainbowfishes of the Bird's Head (Vogelkop) region of West Papua, Indonesia. The full work — Nugraha, Kadarusman, Hubert, Avarre, Hadiaty, Slembrouck, Carman, Sudarto, Ogistira and Pouyaud, published in Cybium 39(2):99–130 under the title 'Eight new species of rainbowfishes (Melanotaeniidae) from the Birds Head Region, West Papua, Indonesia' — described eight new Melanotaenia at once, of which naramasae is one. Eschmeyer's Catalog of Fishes governs the valid name; the species was described in Melanotaenia and remains there, so no parenthetical authority applies.
The genus name Melanotaenia combines the Greek melan, 'black', with the Latinised taenia, 'stripe' or 'band', a reference to the dark lateral marking common in the genus. The specific epithet naramasae is taken from the type locality, the Naramasa River. No single striking feature sets it apart; instead it is diagnosed on a combination of meristic and morphometric characters: dorsal-fin elements IV–V + I,13–15; anal I,21–24; 33–35 lateral-line scales; 15 gill rakers; a relatively deep body (greatest depth 33.3–37.8% of standard length); the origin of the soft dorsal fin lying behind the anal-fin origin; and the absence of stripes along the margins of the anal and dorsal fins.
Morphology
Melanotaenia naramasae is a small, laterally compressed, moderately deep-bodied rainbowfish. FishBase records a maximum length of about 4 in SL, a figure based on the type material and flagged as provisional; the holotype itself measures roughly 3 in SL. It runs deep for the genus, with the greatest body depth measured at 33.3 to 37.8 percent of standard length.
The diagnostic fin counts are a divided dorsal fin of four to five spines in the first portion followed by one spine and 13 to 15 soft rays in the second, an anal fin of one spine and 21 to 24 soft rays, 33 to 35 scales along the lateral series, and 15 gill rakers. Two further features are diagnostic: the origin of the soft dorsal fin sits behind the origin of the anal fin, and the anal and dorsal fins lack the dark marginal striping seen in some congeners. Detailed live colouration is not well documented in the available sources — there is no FishBase photograph — so this profile does not assert a colour pattern the record does not support; data on the living fish's appearance are sparse.
Habitat
The species is endemic to the Bird's Head (Vogelkop) region of West Papua, Indonesia, and is known from the Naramasa River, its type locality. The type series was collected from a river flowing through primary rainforest over a bottom of gravel and sand, with the specimens found chiefly along the riverbank in association with submerged log debris.
This is clear, flowing forest-stream water, not a still lake — which separates it from the better-known Vogelkop rainbowfishes that live in lakes. FishBase characterises the species as a freshwater, benthopelagic fish of tropical waters. Specific physico-chemical data — temperature, pH, hardness — for the Naramasa River were not captured in the sources available for this profile, so precise water parameters are not asserted here; the broad picture is of warm, clear, well-oxygenated rainforest stream water over a gravel-and-sand bed.
Feeding
No species-specific diet study is available for Melanotaenia naramasae. FishBase places it at a modelled trophic level of roughly 2.9, consistent with the omnivorous-to-mildly-predatory feeding typical of the genus, in which rainbowfishes take small aquatic and terrestrial invertebrates along with algae and plant material.
By inference from the genus and from the habitat — a forest stream where the fish shelter around log debris near the bank — the natural diet is most likely small invertebrates drifting in the current and picked from submerged surfaces, supplemented by algae and fine plant matter. The available record does not document stomach contents or feeding behaviour directly, so this account treats the diet as an informed inference rather than a measured fact.
Mating
There is no published account of courtship or spawning behaviour for Melanotaenia naramasae specifically. The species was described in 2015 from preserved type material, and FishBase records no maturity, reproduction or spawning data for it.
Rainbowfishes of the genus Melanotaenia are, as a group, egg-scattering plant-spawners in which displaying males court females over fine vegetation and the pair release small numbers of adhesive eggs at a time, typically with no parental care. These genus-level generalisations are the best available guide to how naramasae is likely to behave, but they are inference, not observation; the specific mating biology of this fish remains undocumented.
Breeding
No breeding records exist for Melanotaenia naramasae in the sources consulted. The species is not established in the commercial aquarium trade, and no hobbyist or scientific account of captive or wild reproduction was located. FishBase lists no reproduction, fecundity or development data.
Where relatives in the genus have been bred, the pattern is consistent: adhesive eggs deposited on fine-leaved plants or spawning mops over an extended period, hatching after roughly a week to a week and a half at warm temperatures, with tiny fry requiring very small first foods. Whether naramasae conforms to that pattern is plausible but unverified. Pending direct observation, the honest position is that the breeding biology of this species is unknown.
In the aquarium
Melanotaenia naramasae has essentially no aquarium track record. Described only in 2015 and restricted to a single West Papua river, it has not entered the ornamental-fish trade in any meaningful way, and no dedicated hobby care or breeding page for the species could be located. FishBase notes a general aquarium potential for the species, but that reflects the appeal of the genus rather than established husbandry experience.
Any keeping advice has to be borrowed from general Bird's Head Melanotaenia husbandry: clear, well-oxygenated, warm tropical water around the mid-20s Celsius; a group rather than a pair, since the genus is social and shows best in numbers; an open swimming lane with some current; and a varied omnivore diet. These are reasonable defaults, not species-specific guidance, and a prospective keeper should treat husbandry for this fish as provisional. The data here are sparse by design — the species is far better known as a scientific entity than as an aquarium fish.
Conservation
Melanotaenia naramasae is assessed as Endangered (EN) on the IUCN Red List under criteria B1ab(iii), in an assessment dated 4 December 2019 (IUCN species ID 161109855). The listing rests on the species' extremely restricted range — it is known from a single river system in West Papua — combined with an inferred decline in the extent and quality of that habitat, which is what the B-criterion captures.
A fish confined to one forest stream has little buffer against habitat change — there is no large outlying population to absorb a local decline. CITES has not evaluated the species. Unlike some of its lake-dwelling relatives, naramasae has not been subject to heavy collection for the aquarium trade, simply because it is not established in that trade; the principal concern is the integrity of its single, small native range rather than collecting pressure. Continued protection of the Naramasa River catchment and its surrounding primary forest is the central conservation need.