Taxonomy & naming
Chiloglanis bifurcus was described by South African ichthyologists Ridley B. Jubb and Percy J. le Roux in 1969. It belongs to the family Mochokidae, the African squeakers and upside-down catfishes, within the large suckermouthed genus Chiloglanis — the "rock catlets" — which the Catalog of Fishes treats as the valid combination for this species. It is one of eight formally recognised Chiloglanis species native to southern Africa.
Genetic work comparing mitochondrial sequences has shown Chiloglanis bifurcus to be closely related to, but distinct from, the more widespread Chiloglanis anoterus, with sequence divergence in the neighbourhood of 2.5–2.9 percent — consistent with a comparatively recent evolutionary split between the two rock catlets of the eastern South African escarpment rivers. As with other members of the genus, no older synonymous combination under a different genus is in wide use for this species; it has been placed in Chiloglanis since its description.
Morphology
Chiloglanis bifurcus is a genuinely small catfish, reaching only about 2.5–3 in standard length at maturity — this is the real adult size, not a juvenile measurement, and it never approaches the proportions of the larger Synodontis squeakers. Like all rock catlets it has a flattened head and a ventral, sucker-like oral disc formed from the lips, which it uses to cling to smooth rock faces in fast current, functioning much like the mouth-disc of a hillstream loach even though the two groups are unrelated.
Described morphological detail includes eight pectoral-fin rays, a caudal fin whose upper lobe is longer than the lower (the "bifurcus" in its name refers to this forked, asymmetric tail), roughly eight widely spaced mandibular teeth, and small conical tubercles scattered over the head and body. As in other Mochokidae the skin is naked — there are no scales — which makes the species, like other scaleless catfish, sensitive to copper-based medications. The dorsal and pectoral fins carry stiff, sharp spines that can inflict a wound if the fish is handled carelessly or caught in a net.
Habitat
This species is a narrow-range endemic of the Crocodile–Incomati river system in South Africa's Mpumalanga province, with an additional population recorded in the upper Mlumati (Komati) River in Swaziland (Eswatini), at altitudes of roughly 900–1,656 ft. It lives in rocky rapids and cascades, favouring the deeper runs — around 12–23.5 in of water — flowing over cobbles and bedrock, where current keeps the water well oxygenated.
Water in these upland rivers is moderately warm and close to neutral: recorded conditions are about 73–79 °F with a pH around 6.5–7.2. This is a fast-flowing, well-oxygenated, rocky-substrate river fish, not a soft blackwater species and not a still-water fish — the current itself is part of its habitat requirement, both for oxygen and for delivering the algae and invertebrate food it grazes from rock surfaces.
Feeding
Chiloglanis bifurcus is a nocturnal benthic grazer, feeding mainly after dark on invertebrates and algae scraped from rock surfaces with its sucker-mouth. Recorded prey includes mayfly and caddisfly nymphs, blackfly and midge larvae, and small snails, gleaned from the biofilm coating the cobbles of its rapids habitat.
Where the species has been kept, it has been reported to accept algae-based foods along with bloodworm and flake, but it is a specialist grazer by nature rather than a generalist scavenger, and its dependence on a constant supply of naturally growing biofilm in flowing, well-oxygenated water makes it a poor fit for a typical static aquarium diet.
Mating
The species is oviparous with distinct pairing reported in the wild, rather than indiscriminate group spawning. Courtship and pair formation occur on the rapids and cascades the fish inhabits, timed to a partial spawning season through the southern-hemisphere summer months. Detailed observations of courtship behaviour have not been published in the sources available here, and nothing about this species' mating has been documented from aquarium conditions — it is not part of the hobby trade.
Breeding
Breeding in Chiloglanis bifurcus is a substrate-hiding strategy rather than open-water egg-scattering: reports describe the pair concealing eggs within the gravel and cobble interstices of its rapids habitat, with spawning activity spread across part of the summer rather than a single event. There is no documented parental guarding behaviour beyond this concealment strategy in the material available.
This species has essentially no breeding record in captivity — it is not established in the aquarium hobby at all, let alone bred there. Given its Critically Endangered status and its very specific requirement for flowing, oxygenated, rocky habitat, any conservation-breeding effort would need to replicate river-rapids conditions closely; this is a case where honesty about the absence of aquarium breeding matters more than speculation.
In the aquarium
Chiloglanis bifurcus is not a hobby fish. It is a Critically Endangered, narrow-range South African/Swazi endemic with no meaningful presence in the aquarium trade, and given its conservation status it should not be collected or kept outside of accredited conservation or research programmes. Its real adult size of under 3 in is genuinely small, but small size does not make this an easy aquarium candidate — its needs are specialised, not modest.
What is known of its requirements points to a demanding rheophilic setup: strong, oxygen-saturated flow from a powerful filter or pump, a smooth cobble-and-sand substrate with mature biofilm/algae growth for it to graze, and stable, cool-to-moderate water in the 73–79 °F, pH 6.5–7.2 range. As with all naked-skinned catfish it would be sensitive to copper and should be dosed conservatively with any medication. Its dorsal and pectoral spines are sharp enough to injure a careless handler, so any fish should be moved in a container rather than netted. None of this is offered as encouragement to keep the species — it is offered so that anyone encountering wild populations, or captive-conservation stock, understands what the fish actually needs.
Conservation
The IUCN Red List assesses Chiloglanis bifurcus as Critically Endangered (assessed 2016, criteria A2ace). It is restricted to the Crocodile–Incomati river system in South Africa and the upper Mlumati (Komati) River in Swaziland (Eswatini) — an exceptionally small native range for a freshwater fish, which itself is a major conservation liability.
The population has reportedly declined by around 90 percent over the past decade, driven by dam construction fragmenting and altering its rapids habitat, water pollution, and the spread of invasive fish species through its river system. Because the species depends on flowing, well-oxygenated, rock-bottomed rapids, impoundment and flow modification are especially damaging to it. It is a clear example of a highly specialised endemic catfish whose survival is tied directly to the health of one small river system rather than to any broader regional population.