Taxonomy & naming
Mogurnda wapoga was described by Gerald R. Allen and S. Renyaan in 1996 from specimens collected in the Wapoga River drainage of Irian Jaya, the Indonesian half of the island of New Guinea (now administered as the province of West Papua). The Catalog of Fishes places the genus Mogurnda in the family Eleotridae — the sleepers and gudgeons — not in the Gobiidae proper. The distinction matters: true gobies have their pelvic fins fused into a cup-shaped sucker disc, whereas eleotrids keep the fins separate, and that single character is the clearest way to tell the two families apart in the hand. In the hobby, Mogurnda species are routinely marketed as "purple-spotted gobies" or simply "gudgeons", and both names turn up in care literature; the more precise common name is Wapoga gudgeon, though no widely established vernacular appears to have attached itself to this particular species.
No earlier combination has been confirmed in the literature for M. wapoga — it was described directly into Mogurnda and has not been moved. The genus Mogurnda is the largest elotrid genus centred on New Guinea and Australia, encompassing more than twenty described species of small, cave-spawning freshwater gudgeons. The Catalog of Fishes is the authority for valid names used here.
Morphology
Mogurnda wapoga is a compact, bottom-oriented fish that reaches a maximum standard length of about 2.5 in. The body is moderately elongate and somewhat flattened below, as is typical of demersal eleotrids that spend much of their time resting on or very close to the substrate. Colouration is striking for the genus: the upper back is blue-grey, the head and ventral surface yellow-tan, and the midbody carries a band of iridescent blue with red spotting — a pattern that can flash brilliantly under side-lighting in an aquarium. Unpaired fins are well developed in breeding males.
Sexual dimorphism follows the Mogurnda template: males are generally larger, more intensely coloured, and develop more extended finnage than females, which are typically smaller and plainer. As with related congeners, a ripe female will appear noticeably fuller-bodied. The pelvic fins are separate, not fused — the key structural difference from the true gobies — and the species lacks any sucker apparatus.
Habitat
The Wapoga drainage lies in the lowlands of western New Guinea, and the collection habitat for M. wapoga is described as a small swampy pond on a floodplain — still or nearly still, very shallow water (0–3 ft), over soft mud substrate with leaf litter, in tropical rainforest. This is a warm environment: recorded temperatures from natural habitat data fall around 81–84 °F. The pH range in natural waters spans from approximately 6.6 to 8.0, suggesting the species tolerates a fairly broad range of carbonate hardness conditions, though the warmer, shaded floodplain habitat is likely to trend toward soft to moderately hard water.
This is a strictly freshwater fish. The Wapoga drainage is an interior floodplain system with no evidence that M. wapoga makes any use of marine or estuarine environments; it is a resident species and the whole life cycle is completed in fresh water. Submerged leaf litter and mud provide both cover and foraging habitat.
Feeding
Mogurnda wapoga is a micro-predator. In the wild, related Mogurnda species are known to take worms, aquatic insect larvae, small crustaceans and plant material, and also small fishes when these can be caught — a dietary breadth typical of small to medium eleotrids that exploit whatever live prey is available on or near the substrate.
In captivity, the genus generally does best on a varied diet of live and frozen meaty foods: bloodworm, brine shrimp, daphnia, cyclops, tubifex and similar items. Dry flake is typically refused or taken only reluctantly, and a fish maintained solely on flake tends to lose condition. Sizing prey to the fish's small mouth is important, particularly for juveniles. Regular feeding with small frozen or live items is the single most important dietary practice for keeping this species well.
Mating
Like all resident Mogurnda, M. wapoga is a cave-spawning substrate guardian with genuine parental care — not an amphidromous species, and not an open-water egg-scatterer or mouthbrooder. The male establishes and defends a spawning site: a cave, crevice, overhanging rock, coconut shell or similar enclosed surface, and courts females with extended fins and intensified colour. Courtship in related Mogurnda follows a display in which the male spreads his fins widely to attract a ripe female into his territory.
In a well-set-up aquarium, pairs will self-select from a small group, with the male advertising his site repeatedly to condition females. Males may spar over prime cave sites, so providing multiple potential spawning locations reduces aggression in a group tank.
Breeding
Mogurnda wapoga breeds as a resident cave-spawner in fresh water — the entire cycle takes place without any marine phase, which is what distinguishes resident gudgeons like this species from the amphidromous gobies that cannot be captive-bred. The female lays 20–200 adhesive eggs on a hard surface inside the chosen cave, typically on the roof or wall, and then the male takes sole charge. He guards the clutch and fans it continuously with his fins to maintain oxygenation until the eggs hatch.
The newly hatched larvae are semi-pelagic and small; first foods should be appropriately sized live items such as newly hatched brine shrimp nauplii or infusoria-level micro-foods, graduating to larger live and frozen prey as the fry grow. Because the male's guarding behaviour is active and reliable, a mature tank with suitable caves can yield fry without elaborate intervention, though moving the egg-bearing site to a separate rearing vessel improves survival where predation risk is present. This is the same strategy that makes related congeners like Mogurnda mogurnda a manageable breeding project in the hobby.
In the aquarium
Mogurnda wapoga is a small, demersal gudgeon best suited to a species or semi-species setup rather than a bustling community tank. A tank of 23.5–31.5 in with stable, warm, clean fresh water — 81–84 °F, pH 6.5–8.0 — suits it well. The tank must be densely furnished: bogwood, smooth stones, leaf litter, and multiple caves or hollow structures reduce territorial stress between males and provide the spawning sites the species needs. A dark substrate shows off the fish's iridescent midbody band most effectively. A tightly fitting lid is advisable, as eleotrids are capable jumpers.
It is not a community fish in the conventional sense: it will eat anything it can fit in its mouth, and small, slow tankmates such as tiny rasboras or nano fish may be at risk. It does well with similarly sized, robust companions or in a single-species setup. It needs no salt — this is a freshwater fish throughout its range. Feed live or frozen meaty foods; do not rely on dry flake. Given stable water quality, appropriate temperature, adequate cover and a varied carnivore diet, M. wapoga is a rewarding specialist fish with the added attraction that it can be bred in the home aquarium.
Conservation
Mogurnda wapoga is assessed as Least Concern on the IUCN Red List (assessed 2019), reflecting a population with high resilience and a minimum population doubling time of fewer than fifteen months — characteristics consistent with the small, fast-breeding biology of the genus. The species is known from the Wapoga drainage of West Papua (Irian Jaya), Indonesia, making it an endemic with a geographically limited range.
The primary conservation concern for a drainage-restricted endemic of this kind is habitat degradation: deforestation, agricultural runoff, and land conversion in the New Guinea lowlands can alter or destroy the shallow, leafy floodplain ponds and swampy habitat the species depends on. The Wapoga drainage has historically been relatively undisturbed compared to coastal lowlands, but this may change with ongoing development pressure. Trade collection is not currently identified as a driver of concern; the species is occasionally encountered in specialist aquarium markets but is far less commonly traded than related congeners such as Mogurnda mogurnda.