Taxonomy & naming
Wallaciia anamiri was described in 2015 by Priscila Madoka M. Ito and Lúcia H. Rapp Py-Daniel, both of the Instituto Nacional de Pesquisas da Amazônia (INPA) in Manaus, in the journal Neotropical Ichthyology. The work formed part of Ito's master's revision of the small-bodied pike cichlids. The holotype (INPA 46650), a 1.5 in SL male, was collected by Kirk Winemiller in November 2014 at Itapuama, on the Rio Xingu just below its confluence with the Rio Iriri in the Brazilian state of Pará. A paratype series of more than forty specimens, drawn from collections at INPA, the Academy of Natural Sciences (ANSP), the Museu Paraense Emílio Goeldi, the Museu de Zoologia da Universidade de São Paulo and the Universidade Federal do Pará, anchors the description. The species name is registered under ZooBank act 49DA7992-4867-4436-8DA4-D6A0F698D59B.
The fish was no stranger to ichthyologists before 2015. Sven Kullander had noticed the undescribed Xingu form as early as 1990, remarking on its resemblance to Crenicichla urosema and Crenicichla virgatula; aquarium writers Frank Warzel (in Konings' Cichlids Yearbook, 1992) and J. Gottwald (2007) had figured and discussed it under provisional names such as 'Crenicichla sp. cf. regani' and 'Crenicichla sp. aff. urosema'. Ito and Rapp Py-Daniel placed anamiri firmly in the Crenicichla wallacii species group, the assemblage of dwarf pikes diagnosed since Kullander (1990) and Ploeg (1991) by serrations on the supracleithrum (the bone at the upper edge of the gill opening) — a feature absent in the larger pike cichlids. They counted it the eleventh species of Crenicichla recorded from the Xingu basin.
Nomenclature in this genus is now in flux. A major integrative phylogenetic revision of the pike cichlids by Varella, Kullander, Menezes, Oliveira and López-Fernández (2023, Zoological Journal of the Linnean Society) broke the long-overgrown Crenicichla into several genera; under that classification the wallacii group is transferred to the genus Wallaciia, and FishBase and several databases now list this fish as Wallaciia anamiri. The combination Wallaciia anamiri remains the original and still widely used name, and the species is treated here under it; readers should simply be aware that Wallaciia anamiri denotes the same fish.
Morphology
This is a genuine dwarf. The original description was based on 44 specimens, the largest only 2 in (about 2 in) standard length; the holotype itself is 1.5 in SL. The body is elongate and laterally compressed in the typical pike-cichlid mould, with the head longer than deep, a rounded-to-moderately-pointed snout, and a slightly protruding lower jaw — but the whole package is scaled down to the size of a dwarf Apistogramma rather than a true pike. Fin counts run to XVIII–XXI dorsal spines with 8–11 soft rays, three anal spines with 7–10 soft rays, and 30–32 vertebrae; the preopercle margin carries 12–21 well-developed spines, and the supracleithrum bears one to six serrations, the hallmark of the wallacii group.
In life the fish wears a broad dark longitudinal band running from the snout through the eye to the tail — densely black on the head, fading to dark grey along the body — overlaid by about nine short, irregular vertical bars. The back and crown are a dull yellow, the belly pale yellow, and the dorsal and anal fins a soft yellow; females add a thin greyish submarginal line on the dorsal fin underscored by a reddish-orange stripe. The diagnostic mark is a large, black, vertically elliptical blotch set centrally on the base of the caudal fin, followed by three to four fainter dark vertical bars across the tail and a scatter of diagonal white streaks above. This combination separates anamiri from its closest relatives: Crenicichla notophthalmus and Crenicichla regani carry an ocellated spot on the upper part of the tail base rather than a central blotch, while Crenicichla urosema and Crenicichla virgatula lack the vertical caudal barring and have more teeth (more than four rows, versus two to four in anamiri). Sexual dimorphism follows the dwarf-pike pattern — ripe females become noticeably deeper-bellied and develop the coloured dorsal markings, while males stay slimmer and grow somewhat larger with more pointed fins.
Habitat
Wallaciia anamiri is known only from the middle Rio Xingu and the lower Rio Bacajá, upstream of the great river bend known as the Volta Grande do Xingu, in Pará, Brazil — a tightly restricted, endemic range. The Xingu is a classic Brazilian Shield clearwater river: wide, fast-running over vast expanses of bedrock, transparent, and warm, with soft, mineral-poor, slightly acidic water typical of clearwater systems draining ancient crystalline shield. During the dry season the falling river exposes broad sandy beaches and leaves clear shallow pools along the margins.
It is precisely these shoreline shallows, not the rapids, that anamiri occupies. Every specimen in the type series was taken in the dry season with seines and dip-nets close to shore or on sandy beaches, among the submerged roots of the riverside (riparian) trees. This habit sets the dwarf apart from the river's many rheophilic specialists — the larger Crenicichla and the Teleocichla dwarf pikes that cling to swift, rocky channels — and aligns it instead with the slow-water, structure-loving lifestyle of the Amazonian and Guianan members of its own species group. The original authors did not publish in-situ chemistry for the species, but the Xingu's documented clearwater character implies soft, warm water of roughly pH 6 to 7 and temperatures in the high twenties to low thirties Celsius; the fish were collected from quiet, shallow water at the river's edge rather than from any measured depth band.
Feeding
No gut-content study has been published for Wallaciia anamiri specifically, but its anatomy and its place in the wallacii group make its diet plain. Like all pike cichlids it is a micro-predator: the elongate body, large mobile eye, terminal jaws lined with two to four rows of small, pointed, slightly recurved teeth, and a strongly toothed lower pharyngeal plate are the toolkit of a fish that ambushes and seizes small live prey. At a maximum of under five centimetres, anamiri takes correspondingly tiny quarry — aquatic insect larvae, micro-crustaceans, small worms and other invertebrates sheltering among the submerged tree roots and over the sand where it lives. FishBase places it at a trophic level of about 3.1, consistent with a small invertebrate-feeding carnivore rather than a piscivore. In the shoreline community it functions as one of the smallest predators of the leaf-litter and root-tangle microhabitat, the dwarf-pike counterpart to the larger Crenicichla that hunt fish in deeper water.
Mating
The reproductive behaviour of Wallaciia anamiri has not been observed and described in the wild or formally in captivity, so what follows is drawn from its close relatives in the wallacii group, which have long been kept and studied by aquarists. The dwarf pikes form bonded male–female pairs and engage in prolonged, conspicuous courtship; the ripening female advertises her readiness with a swollen, often reddened belly and intensified colour, and in many species of the group with bright ocelli or coloured markings on the dorsal fin that she displays to her partner. Pair formation is fraught: kept together in confined space these little fish are notably belligerent toward one another, and sparring escalates as females come into condition. In aquaria, growing out a group typically yields one dominant compatible pair that then defends a territory around a chosen cavity. As with pike cichlids generally, the female plays the leading role in tending the spawning site while the male patrols and guards the wider territory.
Breeding
Wallaciia anamiri has not, on the published record, been bred and documented, and the Xingu form proved frustratingly reluctant to spawn for the hobbyists who kept it before it had a name. Its breeding biology is therefore inferred from the wallacii group, whose members are cave spawners: the pair selects a sheltered cavity — under the wild root-tangles and rock crevices of their habitat, or a flowerpot, coconut shell or length of PVC pipe in captivity — and the female attaches her eggs to the ceiling or wall of the chamber. Both parents tend the brood biparentally, the female fanning and guarding the eggs and wrigglers within the cave while the male defends the surrounding territory; after the fry become free-swimming the pair shepherds and protects them. Clutch sizes for these dwarfs are small in keeping with the fish's size; no count exists for anamiri, but congeneric dwarf pikes of the wallacii group typically produce on the order of a few dozen to roughly a hundred eggs per spawning. Experienced keepers of the related dwarf pikes report that success hinges on soft, warm, acidic water — peat-filtered or even reverse-osmosis water is often recommended — together with a rich diet of live and frozen foods to bring the female into condition.
In the aquarium
Wallaciia anamiri itself is rarely available, but as the long-traded 'Crenicichla sp. cf. regani Xingu' it has a real hobby history, and the husbandry of the dwarf pikes of the wallacii group applies directly. These are small, characterful fish that can be housed in modest tanks — a footprint around 90 x 17.5 in is workable for a pair or small group — but they are far from easy, chiefly because of their intolerance of one another. Aquarists who have kept the related Amazonian and Guianan dwarfs (Crenicichla regani, Crenicichla notophthalmus, Crenicichla compressiceps and their kin) describe them as highly belligerent intraspecifically: a group grown out in too little space quickly collapses to a single surviving pair. The standard remedy is to provide a colony plenty of broken-up sightlines — dense planting, driftwood, and an abundance of hiding places such as short lengths of PVC pipe, flowerpots and coconut shells — and to include peaceful dither fish (small tetras or Copella pencilfish) to draw the pikes out and diffuse aggression.
Water should mirror the soft, warm Xingu clearwater the species comes from: temperature around 79–86 °F, pH on the acidic side of neutral (roughly 5.5–7.0), and low hardness. The dwarf pikes are sensitive fish best kept scrupulously clean, with gentle filtration and regular water changes; long-time keepers note that coaxing them into breeding condition may require genuinely soft water (peat extract or RO). A sand substrate suits a fish that lives over sandy shallows, and a tight-fitting lid is wise, as pike cichlids are capable jumpers. Diet is straightforward for a small predator: a varied menu of live and frozen invertebrate foods — bloodworm, daphnia, brine shrimp, small worms — with many specimens learning to take quality frozen and prepared foods. Because of its diminutive size, anamiri should never be combined with anything large enough to treat it as a meal; its ideal company is other small, peaceful shallow-water South Americans. Honest expectation-setting matters here: this fish has a decades-long reputation for being kept readily but bred only with difficulty.
Conservation
Wallaciia anamiri has not been assessed by the IUCN Red List and currently carries the status Not Evaluated; it is likewise not listed by CITES. The describing authors did, however, run their own preliminary assessment. Using the type-series localities they calculated an extent of occurrence of about 12,40 mi² and an area of occupancy of about 3,595 mi² — both figures falling just short of the thresholds that would trigger a threatened category, so they concluded the species would key out as roughly Near Threatened rather than Vulnerable.
The overriding conservation issue is the Belo Monte hydroelectric complex, one of the largest dams in the world, which diverts the main course of the Xingu around the Volta Grande into a vast reservoir and has profoundly altered the river precisely within and just downstream of this species' range. Many Xingu endemics — especially the rheophilic fishes tied to fast water and rocky substrates — are gravely threatened by the dam. Ito and Rapp Py-Daniel judged anamiri comparatively less exposed: because it favours marginal sandy beaches and tree roots rather than the rapids, and because it occurs in the Serra do Pardo National Park, a protected area lying away from the dam's direct influence, it may weather the disturbance better than the river's flow-dependent specialists. Even so, the authors stressed how little is known of the biology and resilience of this newly described fish, and the broader collapse of natural flood-pulse and flow regimes across the middle Xingu remains the backdrop against which its future must be read.