Taxonomy & naming
Apistogramma urteagai was described by the Swedish ichthyologist Sven O. Kullander in 1986, in his monograph Cichlid Fishes of the Amazon River Drainage of Peru (Swedish Museum of Natural History, Stockholm), on pages 163 and following with figures 51-53 and plate 17. The holotype, NRM 16659, is held in the fish collection of the Naturhistoriska Riksmuseet in Stockholm, with an extensive series of paratypes deposited there and at the California Academy of Sciences, the Academy of Natural Sciences in Philadelphia, and the Smithsonian. The type locality is Lago Tupac Amaru, a lake near Puerto Maldonado in the Río Madre de Dios drainage of southeastern Peru. The name has stood unchallenged since: the Catalog of Fishes lists no synonyms, and the species has been treated as valid in every subsequent checklist and revision, from Kullander's own 2003 treatment in the Reis et al. checklist of South American freshwater fishes to Römer's Apistogramma atlases and Staeck's field guides. Within the genus it sits in the Apistogramma regani species-group — the most widely distributed and, on morphological grounds, one of the more ancestral assemblages in the genus, characterized by a full complement of infraorbital and lower-jaw sensory pores and a generally plain two-banded body. In the hobby it carries the DATZ catalogue number A035 and is occasionally sold under the made-up trade label 'Madre de Dios dwarf cichlid', but no settled English common name has ever attached to it.
Morphology
This is a true dwarf cichlid. The largest measured specimen on record is about 1.5 in in standard length (the snout-to-tail-base measurement), and most adults fall between 3 and 1.5 in; including the tail, a large male is still well under two inches. The body is the typical Apistogramma shape — oval, moderately compressed, with a rounded to slightly extended tail. At rest the species is plain: the back is olive-drab to grey, the belly white, the flanks marked by the genus-standard longitudinal band and a row of lateral spots, and the fins largely clear. The interest is in the differences between the sexes and in how dramatically the fish change with mood. Males are the larger sex and, especially when courting, light up with a metallic teal or blue-green sheen down the centre of the body and across the gill covers, with flecks of the same colour on the leading rays of the anal and ventral fins. Females are smaller and, outside of breeding, drab — but a female tending eggs or fry switches to a brilliant warm yellow set off by sharp black markings, the classic mother-Apistogramma livery that warns rivals away from the nest. Both sexes throw up bold black vertical bars and a dark lateral stripe when stressed or sparring, a quick read on the fish's state of mind. The subdued baseline colouring is the main reason urteagai never became a hobby staple the way its flashier cousins did; it is a fish whose appeal is in behaviour rather than in a shop tank.
Habitat
Apistogramma urteagai is endemic to the Madre de Dios River basin, a tributary of the Madeira in the Amazon system, where its range straddles the Peru-Bolivia border in the Andean foothills and adjacent lowland of the southwestern Amazon; the Catalog of Fishes and the IUCN both give the distribution as Peru and Bolivia, with records reported between roughly 140 and 250 metres elevation, and the species' presence in adjacent Brazil treated as uncertain. It is a fish of small, slow waters rather than the main river. In the Tambopata-Candamo reserve it was recorded in clear and mixed black-and-white-water streams over sandy and stony bottoms strewn with fallen logs; aquarists collecting near Puerto Maldonado have taken it from shallow, sluggish marsh-fed creeks (the Loboyoc marshlands) where it shelters among submerged roots and leaf litter along the calmer margins. The IUCN classes its habitat as permanent streams and inland wetlands — bogs, marshes and swamps. The water is soft and acidic: field measurements at one collecting site ran pH 5.5 to 6.5 with dissolved solids of only 12 to 22 ppm and a temperature around 77 °F (77 °F), and FishBase summarizes the species' envelope as pH 5.0-6.0, hardness 6-10 dH, and 72–84 °F. No formal depth band has been published — like most stream Apistogramma it lives in the shallow shoreline zone, generally within the top metre or so of water — so the depth figures here are inferred from habitat rather than measured.
Feeding
Like its congeners, Apistogramma urteagai is a micropredator that works the leaf litter and soft sediment of its home streams for small invertebrates — insect larvae, microcrustaceans and other meiofauna sifted from the bottom and from detritus. FishBase places it at a trophic level of about 3.3, the carnivore-leaning omnivore band typical of the genus, and care references describe it as omnivorous with a clear carnivorous tendency. In the wild this puts it among the small bottom-oriented predators of the litter zone, sharing that microhabitat with tetras, Corydoras catfishes and other dwarf cichlids. In captivity the diet preference shows plainly: keepers report that wild fish thicken up and come into breeding condition fastest on live and frozen foods — daphnia, mosquito larvae, glassworms, blackworms, white worms and chopped earthworm — and will take prepared flakes and micro-pellets readily enough, but grow and breed best when the menu leans heavily toward live prey.
Mating
Apistogramma urteagai is polygamous, organizing itself into the harem system common to the genus: a dominant male holds a larger territory overlapping the smaller territories of several females, courting and spawning with each in turn rather than pairing off. A sex ratio biased toward females — keepers suggest something like three females per male — suits this arrangement and spreads the male's attention so no single female is harassed. Courtship is a male affair of fin-spreading and colour display, the teal flush at its most intense; the female signals readiness by colouring up and retreating to a chosen cavity. Once she has eggs to defend the social order inverts. The brooding female becomes the aggressor, blazing yellow and driving off everything that approaches the nest, the male included — observers describe the male being chased away 'with a vengeance' the moment fry are present. Males remain territorial toward one another and toward intruders, but within an established harem the fish coexist with mostly bluster: flaring and chasing that rarely escalates to injury when there is enough space and cover to break up sightlines.
Breeding
This is a cave-spawning dwarf cichlid, and an unusually easy and prolific one. The female chooses a sheltered cavity — in the wild a hollow under wood or among roots, in the aquarium a flowerpot, coconut shell or length of pipe — and lays her eggs on its ceiling and walls, where she alone tends them; FishBase records eggs attached to the roof of caves with the female caring for eggs and larvae. Clutches are modest: a wild-caught female documented by aquarists laid around 50 maroon-coloured eggs covering the top and one side of an upturned pot. The female fans and guards the eggs inside the cavity while the male patrols the surrounding territory and keeps other tankmates at bay; the eggs hatch in about two days, the larvae wriggle on the floor of the cave for roughly three more, and the fry are free-swimming about five days after spawning, emerging as a tight cloud around the mother. From that point the female alone shepherds them, and she is a notably good and committed parent. Spawning is triggered by the conditions of the wild environment — soft, acidic water, frequent water changes and a rich live-food diet — and once a group is settled the fish can spawn in waves: one keeper working with wild stock reported four females brooding simultaneously in a single modest tank and an output of 150 to 200 young, calling them 'the most prolific' Apistogramma he had kept. Fry grow quickly on newly hatched brine shrimp and powdered foods.
In the aquarium
Apistogramma urteagai is genuinely rarely kept. It appears in the hobby sporadically — usually as wild-caught imports from Peruvian exporters working the Puerto Maldonado area — and turns up at specialty cichlid vendors and society auctions more often than in mainstream fish shops. That said, keepers who have worked with it consistently describe it as one of the easier and more rewarding small Apistogramma to maintain and breed, partly because it is hardy within its chemistry requirements and partly because it is an unusually willing and prolific spawner once established. A small group is manageable even for a moderately experienced hobbyist who is willing to attend to water quality.
Because wild males reach only about 1.5 in standard length and females are smaller still, this is a species that can be kept in a relatively small dedicated aquarium. A single pair will function in a tank of around 15 US gal, but a proper harem — one male and two or three females — is better served by 20–30 US gal with a footprint long enough to allow the male a central territory and each female her own cave and buffer zone. The substrate should be fine sand, deep enough to show it off (Apistogramma urteagai forages by sifting and mouthing the bottom), and the aquascape should include a generous scatter of dried Indian almond or oak leaves, pieces of driftwood, and root tangles. For spawning sites, upturned terracotta pots with a small hole in the base, coconut-shell halves, short sections of PVC pipe, or commercial Apistogramma caves all work; provide at least one site per female plus a spare, and distribute them so females cannot see each other's entrances. Low light, soft planting, and floating plants that block surface glare make the fish more confident and improve colour display.
Water chemistry is the single non-negotiable. In the wild this species lives in soft, acidic water — pH 5.0–6.0, general hardness below 10 dH — and the same envelope applies in the aquarium. Attempting to keep or breed it at pH 7.0 or above, or in medium-hard tap water without treatment, will suppress breeding and predispose the fish to bacterial infections; a pH of 5.5–6.5 and GH of 2–8 dH is the working target, achieved with RO or rain water topped up with a small percentage of remineralized water, or by ageing water over peat. Temperature 75–81 °F (75–81 °F) covers the full year; slight seasonal variation — a degree or two cooler for a few weeks — can help trigger a spawning cycle, though keepers report that consistent warm soft water alone is usually sufficient. Frequent small water changes (20–25% two to three times per week) are more important than dramatic temperature swings; the fish comes from small, rain-fed streams where the chemistry is dilute but relatively stable, and stale water is the most common cause of refusal to spawn.
For tankmates, the cautious default is a species-only setup. This is a small fish that can be bullied badly by anything active or nippy, and the brooding female, though ferocious in defending her fry, is still only four centimetres long. In a larger aquarium, suitable companions are small, peaceful species that stay in the middle and upper water column and do not compete directly with the bottom-dwellers: small tetras (cardinals, rummynoses, embers, or similar soft-water Amazonian species work well), a few small Corydoras on the substrate, and perhaps a pair of pencilfish or a small hatchetfish school. Avoid anything fast enough to consume fry — most tetras over 1.5 in will pick off the newly free-swimming young — and avoid other bottom-dwelling cichlids entirely. Within the Apistogramma group, the species is not a community fish; combining it with other Apistogramma is generally inadvisable unless the tank is large and heavily structured.
Sexing is straightforward once the fish are adult: males are noticeably larger and develop the teal/blue-green lateral flush and extended fin tips, while females remain smaller, more uniformly olive-drab or yellow-olive, with rounder bodies and shorter fins. A brooding or alarmed female turns a bright lemon-yellow with sharp black markings that are unmistakable. The commonest keeper mistake is running too small a group, typically a single pair, which results in the male over-courting and stressing a lone female. Running two or three females per male distributes attention and also provides competitive cues that seem to encourage the females to spawn more readily. A second common error is buying a group from a supplier at neutral pH and attempting to lower the pH gradually — the fish often survive this but never come fully into colour or breeding condition; starting with properly soft, acidic water from day one produces noticeably better results.
Conservation
The IUCN Red List assesses Apistogramma urteagai as Least Concern (assessed 25 April 2014 by Carvajal, Sarmiento, Reis and Lima; published 2016), citing a fairly large distribution in a remote and partly protected area and the absence of any major range-wide threat. The population trend is judged stable, and part of the Madre de Dios basin within its range lies inside protected lands — the Manu National Park and Biosphere Reserve and the Bahuaja-Sonene reserve. It is collected for the aquarium trade, but only sporadically and at volumes the assessment does not consider a threat; it carries no CITES listing. The one substantial pressure the assessors flag is not specific to this fish but bears directly on it: gold mining in the upper Madre de Dios basin. Artisanal and industrial gold extraction there is among the most acute environmental problems in the Peruvian Amazon, stripping forest, choking rivers with sediment and loading the water with mercury, and it degrades exactly the clear-water, sand-and-leaf-litter stream habitats this species depends on. For now Apistogramma urteagai's remoteness and the protected status of much of its range keep it secure, and the honest summary is the one the Red List gives — a species of no present concern living in a basin whose long-term health is not guaranteed.