Taxonomy & naming
Chilatherina campsi was described by the Australian ichthyologist Gilbert Percy Whitley in 1957, in a paper titled 'Fishes from inland New Guinea' published in the Records of the Australian Museum (volume 24, part 3). The type material came from a small creek flowing into the middle Jimmi River, roughly six degrees northeast of the Mount Hagen airstrip at an altitude of about 1,200 feet, collected on 21 July 1954 by E. Troughton and N. Camps. The species was originally placed in a different genus and is now combined in Chilatherina, which is why the authority is cited in parentheses as (Whitley, 1957). Eschmeyer's Catalog of Fishes governs the valid name; FishBase lists the species under SpecCode 25605.
The genus name Chilatherina combines the Greek cheilos, 'lip', with atherina, an old Greek name for the silverside or smelt — a nod to the family's superficial resemblance to the marine silversides. The specific epithet campsi is a patronym honouring Norman John Ernest Camps, an assistant preparator at the Australian Museum between 1949 and 1955, who collected fishes from the Jimmi River during the expedition that yielded the type series. Chilatherina is one of the New Guinea rainbowfish genera within the family Melanotaeniidae, the true rainbowfishes that radiate across New Guinea and northern and eastern Australia.
Morphology
Chilatherina campsi is a moderately elongate rainbowfish. FishBase records a maximum length of about 3 in SL (Allen, 1991), while an Australian import-risk assessment cites larger wild fish of roughly 3–3.5 in SL — so a mature adult of around 3 in is a reasonable expectation, with the genus's typical laterally compressed, gently deepened body. As in other rainbowfishes the dorsal fin is divided into a short spiny portion and a longer soft-rayed portion; published meristics give 6 to 8 dorsal spines, 12 to 16 dorsal soft rays, a single anal spine, and 21 to 26 anal soft rays.
The live fish is marked by a broad blue mid-lateral stripe, most prominent along the posterior half of the body and set against a paler ground. The fins are largely white, sometimes with a yellow suffusion. Males run deeper-bodied than females and carry a more intense pattern, the usual sexual dimorphism of the family. Two colour forms are recognised in the aquarium — red-finned and blue-finned — reflecting geographic or strain variation across the species' wide range.
Habitat
This is the rainbowfish of the central highlands of Papua New Guinea, and its common name records that origin. It is unusual among Chilatherina in occurring on both sides of the Central Dividing Range, appearing in the north-flowing Markham, Ramu and Sepik drainages and the south-flowing Purari drainage. Recorded localities include Oomsis Creek and the Wampit River in the Markham, and the Lima, Pima and Wahgi Rivers in the Purari system, with most sites lying in the northern drainage division. It was first collected in 1954 from a tributary of the Jimmi River, some 261 mi from the mouth of the Sepik by way of the Yuat River.
The species favours clear, moderately fast to swift-flowing streams over rock, gravel or sand, typically in relatively open, sunlit rainforest reaches where the fish shelter among aquatic plants, roots and fallen branches. The water is generally soft and slightly turbid. Recorded conditions are warm and slightly alkaline: temperatures of about 21 to 26 degrees C and pH around 7.6 to 7.8 (FishBase gives a comparable 7.5 to 7.8). The elevational range is broad — roughly 200 to 1,1722 ft, with at least one lowland record near 262 ft in the Ramu valley — which is consistent with the species' wide highland distribution. Co-occurring rainbowfishes include Melanotaenia affinis, M. pimaensis and Glossolepis species.
Feeding
No diet study specific to Chilatherina campsi has been published, so the picture here is drawn from the genus and family rather than from this species directly — the data are sparse. Rainbowfishes of New Guinea are opportunistic omnivores, and Allen (1991) characterises the group as eating a mix of algae, ants and other terrestrial insects that fall onto the water, aquatic insect larvae, and small crustaceans. FishBase places the species at a low trophic level of about 2.9, consistent with a largely invertebrate-and-algae diet.
In its swift, sunlit highland streams the fish takes drifting and surface invertebrates from the current and grazes algae and small organisms off submerged surfaces. In the aquarium, fish of this genus are undemanding feeders. They accept good-quality flake and small pellets alongside frozen and live foods such as Daphnia, brine shrimp and bloodworm, and a varied diet with a real live or frozen component keeps up colour and condition.
Mating
Breeding behaviour has not been documented in detail for Chilatherina campsi specifically, and what follows is inferred from the well-studied reproductive pattern shared across the rainbowfishes — again, the species-level data are sparse. Melanotaeniid rainbowfishes are egg-scattering, plant-spawning fishes with no parental care, and they spawn over an extended period rather than in a single seasonal event.
In the family generally, dominant males establish display areas and court females with intense colour displays, flaring the fins and flashing the body so that pattern and stripe reach maximum saturation; courtship and spawning are typically most active in the early hours after first light. A receptive female follows a displaying male into fine-leaved vegetation, where the pair release small numbers of adhesive eggs at a time. Males display most vividly in the presence of rivals, so the species is at its most colourful when several males are kept together.
Breeding
Direct breeding records for Chilatherina campsi are lacking, so the account here reflects the standard rainbowfish reproductive mode rather than verified observations of this species. Like other rainbowfishes, it is expected to be a plant-spawner that deposits small, adhesive eggs which hang by fine filaments from fine-leaved plants or, in captivity, from synthetic spawning mops.
In the family, spawning is spread over many days, a female releasing a few eggs daily rather than a single clutch, with eggs hatching after roughly a week or more at typical breeding temperatures and the time shortening with warmth. The adults offer no care and will eat their own eggs, so breeders harvest mops or eggs to a separate rearing container; the tiny fry require very small first foods such as infusoria or commercial liquid fry food before graduating to newly hatched brine shrimp. The first live aquarium specimens of C. campsi were collected by Gerald Allen and Brian Parkinson, and Barry Crockford of Melbourne later collected the species from the Oomsis River near Lae in the early 1980s, which is how it entered the hobby.
In the aquarium
Chilatherina campsi is a stream fish from clear, flowing, slightly alkaline water, and that origin should guide its aquarium care. It is an active, schooling rainbowfish best kept as a group, ideally with several males so that they display against one another and hold their best colour. A long tank with an open swimming lane suits its restless habit, and a planted layout with some current and bright lighting both echoes the natural habitat and encourages the morning display behaviour.
Water should be warm and neutral-to-slightly-alkaline rather than soft and acid: temperatures in the low-to-mid 20s Celsius and pH near 7.5 to 7.8 match recorded field conditions. Given the swift highland streams it comes from, stable, well-oxygenated, clean water with good flow matters more than precise numbers. Tankmates should be similarly sized, peaceful and not easily outcompeted at feeding; other rainbowfishes are the natural companions. The red-finned and blue-finned forms give the species some pull with hobbyists who hunt down the less common New Guinea rainbowfishes, though it turns up in the trade far less often than the popular Melanotaenia species.
Conservation
Chilatherina campsi is assessed as Least Concern (LC) on the IUCN Red List, in an assessment dated 6 December 2019 (Red List version 2025-2). The species is neither listed under CITES nor under the Convention on Migratory Species. Its wide distribution across major river systems on both sides of the Central Dividing Range — the Markham, Ramu, Sepik and Purari drainages — together with its broad elevational range, underpins the relatively secure status. That is the opposite of the narrowly endemic rainbowfishes confined to single lakes.
FishBase rates the species as having low vulnerability to fishing pressure, consistent with its low trophic level and modest size. As with much of inland New Guinea, the principal long-term concerns for highland stream fishes are habitat-level — catchment disturbance, sedimentation and the spread of introduced species — rather than direct exploitation, but no specific declines have been documented for C. campsi, and the current evidence supports its Least Concern listing.