Taxonomy & naming
Peckoltia relictum was originally described as Etsaputu relictum by Lujan, Armbruster and Rengifo in 2011, published in Copeia (volume 4, pages 497–502), from specimens collected at a gravel shoal near the community of Tsantsa, 36 mi north of Imacita, Cenepa River, Amazonas Department, Peru (4°33'37"S, 78°11'07"W; elevation 748 ft). The description erected the new monotypic genus Etsaputu to accommodate it; subsequent systematic work resulted in placement within Peckoltia, and the species is now recognised by the Catalog of Fishes (Eschmeyer, CAS) as Peckoltia relictum (Lujan, Armbruster & Rengifo, 2011), with Etsaputu relictum as a synonym.
Peckoltia belongs to the tribe Ancistrini within subfamily Hypostominae (Loricariidae). The genus honours Gustavo Peckolt (1861–1923), a Brazilian-born German botanist and pharmacist. Within the tribe, P. relictum stands out by a suite of skeletal and external characters that distinguish it from all other hypostomines: a coracoid with a serrated posterior margin on the posterior process; opercle bearing a process extending ventrolaterally; branchiostegals 1 and 2 fused; and cheek plates that evert to less than 45° from the sagittal plane, bearing fewer than ten enlarged odontodes.
Morphology
Adults of Peckoltia relictum reach 3.5 in standard length (SL), making this a small to medium-sized representative of its genus. The body is covered in the typical loricariid bony scute armour; the ventral surface remains soft and unplated.
The most immediately striking external feature is the large eyes, which average 24.0% of head length (range 21.7–27.6% HL) — notably large for a Peckoltia and a diagnostic aid in the field. In life the species displays a uniform gold-brown to bronze base coloration with a golden sheen, a clean appearance that contrasts with the spotted or banded patterns common in many congeners.
Skeletal characters recorded in the original description include the serrated posterior margin of the coracoid's posterior process and the fused first and second branchiostegal rays, neither of which is found in any other hypostomine examined. The evertible cheek plates carrying fewer than ten enlarged odontodes are also diagnostic at the genus level.
Sexual dimorphism follows the broader Ancistrini pattern: males develop small odontodes along the leading rays of the pectoral fins and on the posterior body, while females remain unadorned in these areas and develop a wider girth behind the pectoral fins when gravid.
Habitat
The type locality is a gravel shoal on the Cenepa River in Amazonas Department, northern Peru, at an elevation of 748 ft above sea level. The Cenepa is a river of the Marañon drainage — one of the major Amazonian headwater systems originating in the Andes — and its middle and lower reaches flow through Andean foothill terrain characterised by moderate to swift current over rocky and gravelly substrates.
Foothill rivers in this Andean transition zone typically carry relatively clear, well-oxygenated water, with cooler to warm temperatures depending on season and elevation, and moderate hardness from the calcium-bearing Andean geology. The 'relict' aspect of the species' name and the isolate character of its description suggest that P. relictum is associated with a specific geomorphological feature — the gravel shoal habitat — rather than being distributed broadly across the drainage.
Specific water-chemistry data from the Cenepa type locality are not reported in the available sources.
Feeding
Diet data specific to Peckoltia relictum are not documented. PlanetCatfish notes that the species is not a specialist wood-feeder in the manner of Panaqolus or Panaque — an important distinction for aquarium husbandry. Like most Peckoltia, it is presumed to be an omnivorous scraper, grazing biofilm, algae, and fine organic detritus from rocky substrates, with small invertebrates taken opportunistically.
In captivity, standard loricariid foods — algae wafers, spirulina, and blanched vegetables — supplemented with small invertebrate foods would be appropriate, without the requirement for dedicated driftwood as a dietary staple.
Mating
Mating behaviour in Peckoltia relictum has not been described in the literature or in hobbyist accounts. The sexual dimorphism between males (with pectoral and posterior-body odontodes) and females (wider behind pectorals when gravid) provides the primary cue for sexing, consistent with other cave-spawning Ancistrini. No courtship or territorial behaviour accounts are available.
Breeding
No breeding records for Peckoltia relictum appear in the scientific literature or in PlanetCatfish's curated husbandry database. Based on genus biology and broader Ancistrini patterns, cave spawning with paternal brood care is the expected mode: a male would select and defend a crevice or cavity, with the female depositing adhesive eggs inside and the male assuming responsibility for fanning and guarding the clutch until fry emerge. This remains unconfirmed for this species.
In the aquarium
Peckoltia relictum is not widely known in the ornamental trade; hobbyist accounts are sparse. PlanetCatfish characterises the species as a generalist that does well with rock piles and wood tangles for refuge — unlike the specialist wood-eaters, it does not require driftwood as a dietary component, though wood provides useful cover.
The species is noted as safe with small fish and invertebrates including shrimp, consistent with the generally peaceful temperament of the genus. Water conditions reflecting its Andean foothill origin — moderate temperatures, good oxygenation, moderate hardness — would be appropriate, though specific parameter targets for the Cenepa type locality are not documented.
The distinctive large eyes and bronze coloration make P. relictum an attractive species, and its modest adult size (3.5 in SL) is suitable for a mid-sized community tank. The absence of captive breeding reports means that all available specimens are wild-caught.
Conservation
Peckoltia relictum has not been formally evaluated by the IUCN Red List. The species is known from a restricted area of the Cenepa River drainage in Amazonas Department, Peru — a region within the larger Marañon system. The Cenepa River flows through territory with both indigenous community lands and areas subject to ongoing extractive pressure; the Marañon basin more broadly faces risks from hydroelectric development, gold mining, and deforestation of Andean foothill forests.
Without a population assessment or range surveys beyond the type locality, the conservation status of P. relictum cannot be objectively evaluated. Its apparently limited distribution and specialised habitat association (gravel shoals in Andean foothill rivers) suggest it could be sensitive to habitat modification, but data are insufficient to reach a formal conclusion.