Taxonomy & naming
Chaetostoma machiquense was described by Fernández-Yépez and Martín Salazar in 1953, published in the Memoria de la Sociedad de Ciencias Naturales La Salle (volume 13, number 35, pages 238). The type locality is the Río Negro, 10 mi west of Machiques, Estado Zulia, Venezuela — a tributary draining into the Lake Maracaibo basin. The synonym Chaetostoma machiquensis appears in some older literature but the correct valid name per the Catalog of Fishes (Eschmeyer, CAS) is Chaetostoma machiquense.
The epithet is a toponym: machiquense is the adjectival form of Machiques, a municipality in Zulia State from which the type specimens were collected.
No L-number or C-number coding has been formally assigned to this species. It belongs to the genus Chaetostoma, a diverse Neotropical genus of rheophilic suckermouth catfishes in subfamily Hypostominae. Chaetostoma species are ecologically similar to the rubbernose plecos of the genus Rhinolekos and are sometimes grouped informally under the heading 'rubbernose plecos' in the aquarium trade, though Chaetostoma is the more species-rich and biogeographically widespread genus.
Morphology
Adults reach a maximum of 2.5 in standard length (SL), placing C. machiquense among the smaller members of a genus that itself runs to modest sizes. Total length exceeds SL by a modest margin.
The body is heavily armoured with bony scutes, and the head is broad and depressed in the typical Chaetostoma pattern — the 'rubber-nose' profile that characterises the group. Interopercular odontodes (keratinised spines projecting from behind the gill cover) are present, as in the rest of the genus. Diagnostic negative characters separate Chaetostoma from superficially similar loricariids: the abdomen lacks plates, there are no plates on the snout edge, and the fleshy tentacles characteristic of Ancistrus are absent.
Sexual dimorphism is apparent in adults. Males develop a broader, more robust head shape and a leaner, narrower ventral profile compared with females of the same length. The pelvic fins of males are disproportionately large — notably wider and longer than those of females — a morphological elaboration with a direct reproductive function described below.
Habitat
The known range of C. machiquense is the Negro River basin within the Lake Maracaibo drainage of Zulia State, Venezuela. The Lake Maracaibo drainage is a lowland-to-submontane system fed by Andean and Sierra Nevada foothill rivers; the Río Negro in Zulia is distinct from the famous Amazon tributary of the same name.
Chaetostoma species are characteristic inhabitants of fast-flowing, oxygen-rich streams with rocky or cobble substrates. Rocky riffles and runs, where water tumbles over boulders and creates turbulent, highly oxygenated conditions, are the preferred microhabitat for the genus. C. machiquense is consistent with this pattern, occupying the kind of clear, current-swept rocky river habitat typical of Andean piedmont drainages in northwestern Venezuela.
Specific field measurements of water chemistry at the type locality are not available in the sources consulted.
Feeding
Chaetostoma machiquense is an algae scraper. The broad sucking disc and robust dentition characteristic of the genus are adapted for rasping periphyton — the complex mat of diatoms, filamentous algae, bacteria, and organic detritus that builds up on exposed rock surfaces in fast-flowing streams. Rocky riffles in tropical Andean drainages support dense periphyton communities, and Chaetostoma species are typically the dominant grazing loricariids in these habitats.
In the aquarium, the diet should reflect this algae-scraping ecology. Sinking algae wafers, spirulina-based tablets, and blanched vegetables (courgette, cucumber, spinach) are appropriate staples. Good filtration producing visible current over smooth stones will encourage biofilm growth that the fish will graze naturally. Meaty foods are not a dietary requirement.
Mating
Male C. machiquense are territorially oriented around suitable spawning sites, as is typical for loricariids that breed in fast-moving water. The disproportionately large pelvic fins of males are not merely a secondary sexual character: they play a direct mechanical role during fertilisation. When a male releases milt over a deposited egg clutch in fast-running water, there is a real risk that the current will disperse the sperm before fertilisation can occur. The oversized pelvic fins allow the male to invert — positioning himself upside-down against the substrate — and clamp the fins tightly over or around the egg mass, creating a localised zone of reduced flow that retains the sperm in contact with the eggs long enough for fertilisation to proceed.
This inversion behaviour, where the male guards the clutch pressed upside-down against a flat surface in swift water, is a striking adaptation to fast-water breeding that has been documented in Chaetostoma.
Breeding
Spawning takes place in shallow, fast-flowing water on the underside of a flat object — a smooth boulder face, a large flat cobble, or equivalent hardscape in captivity. The female deposits adhesive eggs on the underside of the chosen surface, after which the male takes position over the clutch and remains with it until the fry emerge.
The male's brooding posture — inverted against the substrate, pelvic fins deployed over the egg mass — is both a sperm-retention strategy during fertilisation and a protective posture during incubation, shielding the eggs from current disturbance and potential predators. The eggs are adhesive and attached directly to the rock surface; the male fans them with fin movements to maintain oxygen supply.
No specific captive breeding data — clutch size, incubation duration, or temperature parameters — appear in the sources consulted for this species specifically. Chaetostoma breeding in general is considered achievable in the aquarium given appropriate conditions: strong current, well-oxygenated water, and flat smooth stones that replicate natural spawning surfaces.
In the aquarium
Chaetostoma machiquense is not a commonly traded species; it does not carry a hobbyist catalogue number and appears sporadically in specialist collections rather than mainstream retail. Nonetheless its care requirements are consistent with the better-known Chaetostoma species.
A furnished tank with strong water movement is essential. Powerheads or high-flow canister filters producing vigorous circulation over a rocky substrate replicate the fast-water riffle environment the species inhabits in the wild. Venturi aerators or spray bars can supplement dissolved oxygen, which must remain high — particularly at warmer temperatures, where oxygen saturation decreases. Water temperature should be maintained in the range suitable for an Andean foothill stream species; broad community-tank conditions of 75–82 °F are likely acceptable, though cooler is generally safer for rheophilic loricariids.
The tank should be furnished with well-rounded cobbles and flat stones stacked to create crevices and caves. These serve as shelter and, in the event of breeding, potential spawning surfaces. Plants are not a requirement and may struggle in the high-flow environment, but robust species attached to rock (Java fern, Anubias) can be included.
A minimum tank footprint of around 60 × 15.5 in is advisable for a single pair; more space is beneficial if a group is to be kept. C. machiquense is not aggressive toward dissimilar species but males of the same genus may dispute territory around prime rock sites.
Conservation
Chaetostoma machiquense has not been evaluated by the IUCN Red List. Its conservation status is therefore unknown, and no formal threat assessment or population data are available in the published literature consulted.
The Lake Maracaibo drainage in Zulia State, Venezuela, faces environmental pressures common to northwestern Venezuela: oil extraction activities in and around Lake Maracaibo itself, agricultural expansion, and deforestation of Andean foothill catchments that reduce water quality and increase sedimentation. Fast-flowing, oxygen-rich rocky streams — the preferred habitat of Chaetostoma — are particularly sensitive to sedimentation events that bury the cobble substrate and reduce periphyton productivity.
In the absence of IUCN data, the conservation status of this species must be considered uncertain. Its restricted known range in the Negro River sub-basin of Zulia warrants monitoring as part of any broader ichthyological survey of the Lake Maracaibo drainage.