Taxonomy & naming
Harttiella janmoli was described by Covain and Fisch-Muller in 2012 as part of their revision of the Harttiini of the Guianas, published in Cybium (volume 36, number 1, pages 115–161). It belongs to the subfamily Loricariinae within the armoured catfish family Loricariidae. FishBase carries the species under SpecCode 66590.
The genus Harttiella comprises a cluster of very small, narrowly endemic loricariines restricted to upland streams of the Guiana Shield. Several of its species — including H. janmoli — were diagnosed in part through DNA barcoding alongside morphology, reflecting how closely similar these miniature catfishes are externally. Among its congeners, H. janmoli is distinguished by its dark brown coloration bearing a single large transverse saddle behind the dorsal fin, in contrast to the five postdorsal bands seen in related species, together with relatively long pectoral and pelvic spines and an elongated body.
Morphology
Harttiella janmoli is a miniature catfish: the type material reaches about 2 in standard length. The body is elongated, and the species carries the typical loricariine armour of bony plates. Ground colour is dark brown, marked by a single large transverse saddle positioned behind the dorsal fin — a diagnostic feature separating it from congeners that show five postdorsal bands. Its pectoral and pelvic spines are comparatively long. Fin-ray counts recorded for the species are seven dorsal soft rays, one anal spine, and five anal soft rays.
No detailed account of sexual dimorphism in this particular species has been published.
Habitat
The species is known only from its type locality: a small forest creek in the Kotika Mountains of French Guiana, at roughly 1690 ft altitude. It is a freshwater, demersal fish of tropical upland streams, living on or near the bottom. This single-stream distribution within a forested upland massif is the defining ecological fact about H. janmoli — it has never been recorded anywhere else.
No published water-chemistry measurements (temperature, pH, hardness) specific to the type creek are available in the consulted sources.
Feeding
No direct dietary study of Harttiella janmoli has been published. FishBase assigns it a modelled trophic level of about 2.8, consistent with the general loricariine pattern of grazing on biofilm, periphyton (attached algae), and associated micro-organisms and detritus rasped from submerged surfaces in flowing forest streams. Specific gut-content or feeding-behaviour data for this species are not available.
Mating
No data on the courtship or mating behaviour of Harttiella janmoli has been published.
Breeding
No data on the reproduction, spawning mode, clutch size, or parental care of Harttiella janmoli has been published.
In the aquarium
Harttiella janmoli is not an aquarium fish. It is a Critically Endangered, single-locality endemic with no presence in the ornamental trade and no documented husbandry. Any encounter with this species belongs to the realm of field study and conservation rather than the hobby, and there are no captive-care guidelines to offer.
Conservation
The IUCN Red List assessed Harttiella janmoli as Critically Endangered (CR) under criteria B2ab(iii), with the assessment dated 14 January 2021. The listing reflects an extremely small range confined to a single forest creek in the Kotika Mountains of French Guiana, where the species faces a projected continuing decline in the quality of its habitat.
With its entire known population restricted to one upland stream, H. janmoli is acutely vulnerable to any localised disturbance — deforestation, sedimentation, water diversion, or pollution affecting that single catchment could be catastrophic for the species. Its specific epithet honours the Dutch ecologist Jan H. Mol, recognised for his work on the protection of Harttiella in neighbouring Suriname, underscoring the conservation concern that has surrounded these miniature Guiana-Shield catfishes from the outset.