Taxonomy & naming
Teleocichla sp. "Tapajos I" is not a formally described species. It has no scientific name, no describing author, no year of publication, and no entry in Eschmeyer's Catalog of Fishes, because no taxonomist has published a description of it. It is an informal taxon of the aquarium and field literature, named in the standard open-nomenclature convention for undescribed rapids cichlids — the genus Teleocichla, the abbreviation "sp.", and a sequential collection code in quotation marks ("Tapajos I"). The genus Teleocichla was erected by Sven O. Kullander in 1988 (Copeia 1988(1): 196–230), founded on six new species and named to emphasise the morphological parallelism with the African rheophilic genus Teleogramma while the "-cichla" element signals the phyletic tie to Crenicichla; Teleocichla and the pike cichlids are small crenicichline geophagines, and the resemblance to African worm cichlids is convergence, not relationship. The genus is restricted to the rapids of clearwater tributaries draining the central Brazilian highlands — the Xingu, Tapajós, Tocantins, and Jari basins. The Tapajós was one of only four localities known to Kullander at the time of description: it yielded Teleocichla proselytus (two localities) and Teleocichla prionogenys (one locality), both taken in the rapids at São Luiz near Itaituba. Kullander himself noted that further exploration would extend the genus's range and turn up additional forms (already in 1990 he counted at least four more undescribed species across the genus), and the Tapajós rapids have since produced several such undescribed Teleocichla, of which "Tapajos I" is one. The honest position is that this is a recognised undescribed Teleocichla of the Tapajós rapids, allied to the described Tapajós species but not formally diagnosed; no authority or date should be attached to it, and its placement in Teleocichla is inferred from body form, habitat, and provenance.
Morphology
Teleocichla are among the smallest and most distinctively shaped American cichlids: elongate, slightly tapered, moderately compressed, goby-like fishes built to wedge into rock crevices and hold station in current. The genus is small-bodied — the largest specimen in Kullander's entire 1988 type series was a Teleocichla cinderella of 3 in SL (under 3 inches), and a gravid female Teleocichla centrarchus measured just 2 in SL — so "Tapajos I" is expected to be a small fish of a few centimetres up to perhaps 3–4 in; one large undescribed Xingu form ("Teleocichla sp. 2") is exceptional in reaching about 6 in total length. A genus hallmark is the pelvic fins, which are long (the middle ray longest), relatively stiff, and thickened along the outer margin — bracing structures for a life on the bottom in fast water. The snout is short and downturned, and the most functionally important feature is the small, picking mouth: unlike the large predatory gape of Crenicichla, Teleocichla has a modest "callionymid" mouth (likened to a marine dragonet's) suited to lifting small invertebrates from rock and biofilm rather than seizing fish. Colour in the genus is cryptic — browns, greys and olive with darker bars, mottling or longitudinal stripes that camouflage the fish against rock and sand, often with fine spotting on the head and fins. Sexual dimorphism is subtle: territorial males tend to be larger and carry more colourful, widespread unpaired fins, while females and subordinate fish are plainer. Because the form is undescribed, no published meristic counts separate it from the other Tapajós Teleocichla; it is recognised by provenance and pattern.
Habitat
This form lives in the rapids of the Rio Tapajós, a major clearwater tributary of the lower Amazon, in the reach around São Luiz do Tapajós and Itaituba in Pará, Brazil — the same stretch that produced the genus's two described Tapajós species. Teleocichla are obligate rheophiles, restricted to cataracts, channels and rapids where clear, warm, oxygen-rich water rushes over and between boulders and coarse sand; all known collections of the genus come from rapids, formerly-rapids reaches, or rocky-bed streams. The fish hold position among the rocks, in crevices and pits and under flat stones, and over the gravel and sand patches between them, avoiding still pools and the open channel. A striking adaptation observed in the field by Stawikowski is that in strong current the fish spread their pectoral fins horizontally like aeroplane wings, so the flow pressing over them pins them to the substrate. No in-situ chemistry has been published for this particular Tapajós form, but the genus's clearwater highland rapids are well characterised from the analogous Xingu sites at Altamira: clear, soft, near-neutral water (pH about 6.5, general hardness around 1°dH, carbonate hardness below 1°, conductivity near 120 µS/cm), very warm at low water (about 90 °F, locally to 95 °F in shallow margins), over rocky bottom in roughly a metre of water — depths and currents that increase greatly in the high-water season. As on the Xingu, the Tapajós rapids are themselves threatened by hydroelectric development (notably the proposed São Luiz do Tapajós scheme), which would flood or alter exactly the fast-water habitat that rheophilic Teleocichla depend on; the type locality of Teleocichla cinderella on the Tocantins was already destroyed by the Tucuruí dam.
Feeding
Teleocichla are small benthic invertivores of the rapids, and their feeding ecology follows directly from their mouth: the small, downturned "callionymid" gape is built for picking, not seizing. They work the rocks and the gravel and sand between them for aquatic insect larvae — chironomids, mayflies, blackfly and the like, abundant in fast oxygenated water — together with small crustaceans, other invertebrates, and the associated organic material and aufwuchs (biofilm and algal growth) on the stones; field observers suspected the fish also pick drifting plankton while peering from their shelters. "Tapajos I" is expected to follow this genus-typical pattern as a micro-invertivore of the rapids biofilm and interstitial fauna. Nothing about its build suggests piscivory; unlike the predatory pike cichlids it is a small crevice-foraging specialist, and its modest mouth excludes large prey. This narrow trophic niche — exploiting small substrate invertebrates in fast water without competing with larger cichlids — is thought to be a large part of why the genus radiated successfully in the rapids.
Mating
Reproductive behaviour in Teleocichla is poorly documented in the wild owing to the inaccessibility of fast-water habitat, but the social structure has been observed directly in the Xingu and is understood to apply across the genus. Adults are territorial: males hold and defend small stones, pits, or holes in stones and retreat under flat rocks when threatened, with the most colourful, widespread-finned individuals being territorial males. Species vary in temperament — some are markedly more social and tolerant, swimming in loose groups, while others are strongly territorial and aggressive — and several Teleocichla are syntopic, so that two or three species may share the same boulder, their reproductive isolation maintained not by separate microhabitats but by differences in courtship, colour pattern, or timing. Larger territorial fish have been seen holding their patch together with several smaller individuals (presumed females and juveniles). Courtship is a close-range affair conducted within and around the chosen rock shelter. "Tapajos I" is expected to share this crevice-oriented, pair-forming pattern; the specifics of its territory size, sociability, and courtship sequence have not been described for this particular form.
Breeding
By analogy with described congeners and their crenicichline relatives, Teleocichla sp. "Tapajos I" is understood to be a cave/crevice-spawning substrate brooder rather than a mouthbrooder. The pattern documented for the genus's relatives, and reproduced in the German aquarium spawnings that first succeeded with imported Teleocichla (Schliewen & Stawikowski, 1989), is for eggs to be laid on the wall or ceiling of a cave or crevice — the captive surrogate being an inverted flowerpot or saucer — and guarded by the pair, the female taking the primary share of egg- and larva-tending while the male defends the immediate surroundings. Clutch sizes in these small cichlids are modest, on the order of a few dozen to perhaps a hundred-plus eggs in keeping with the fish's small body (dwarf crenicichline relatives of comparable size lay roughly 25 to a few hundred eggs); precise figures are not published for this form. The larvae are moved within the shelter and guarded until free-swimming, after which the parents continue to guard and herd the mobile fry through the early stages. Specific wild breeding data for "Tapajos I" are not documented; the account here is genus-typical and flagged as such.
In the aquarium
Teleocichla are specialist fishes for the experienced rheophile keeper, and the undescribed Tapajós forms reach the hobby only sporadically as wild imports. They are not community fish, and they have a hard-won reputation for being difficult: they are awkward to catch, ship poorly, and historically suffered heavy losses in transit and from any spell in non-rheophilic conditions — early American imports of related Teleocichla often arrived more than half dead and the survivors faded quickly without strong current. The lesson from those failures is that the setup must reproduce the rapids from the outset.
Provide strong, well-oxygenated flow — powerheads or a river-tank manifold to generate genuine current — over a substrate of rounded gravel and coarse sand, with smooth boulders and rounded stones arranged into crevices and caves so that each fish has its own bolt-hole. Water should be warm (around 81–86 °F), soft, and near-neutral (pH roughly 6.0–7.5, matching the clear, very soft, low-conductivity chemistry of the natural rapids), and above all high in dissolved oxygen and very clean: these fish tolerate stagnation and poor water quality badly, so vigorous filtration, high turnover, and consistent maintenance are essential. A tight-fitting cover is sensible for these active, current-oriented fish.
Feed small meaty foods suited to a benthic picker — frozen and live bloodworm, daphnia, brine shrimp, and small sinking prepared foods — delivered so they reach the bottom where the fish forages; the small mouth means large pellets are unsuitable. Teleocichla can be territorial toward conspecifics and similar bottom-dwellers (with temperament varying by species), so give a group ample rockwork and space, or keep a single pair. Suitable tankmates are other rheophilic, current-tolerant Amazon fishes of compatible temperament — the same fast-water loricariids and characins that share the habitat; avoid slow-water community fish and anything that will outcompete a small bottom specialist for food. The usual mistakes are too little flow and oxygenation, insufficient rock shelter, lapses in water quality, and trying to acclimate freshly imported wild fish to still water.
Conservation
Teleocichla sp. "Tapajos I" has not been evaluated by the IUCN, and because it is an undescribed form without a formal scientific name it has no Red List assessment of any kind — no status, no category, no published criteria; it stands as Not Evaluated (NE). As an obligate rheophile of the Tapajós rapids it occupies precisely the habitat most exposed to hydroelectric development on the river, most prominently the proposed São Luiz do Tapajós scheme, which would flood and alter the fast-water stretches that current-dependent specialists rely on. The genus already carries a documented precedent: the type locality of Teleocichla cinderella on the Rio Tocantins was destroyed by the Tucuruí dam, leaving that species' status uncertain. Rheophilic cichlids and other rapids endemics of the Tapajós and neighbouring clearwater rivers are widely flagged as vulnerable to such impoundments, which is sharpened for narrow-range, habitat-restricted forms like this one. The conservative position is that this rapids-restricted undescribed form is potentially vulnerable to flow alteration even though it is formally unassessed; no conservation status should ever be fabricated for it, and the honest statement is that it is unassessed, rapids-restricted, and exposed to dam-driven habitat loss.