Taxonomy & naming
Microglanis garavelloi was described in 2005 by Oswaldo Shibatta and Ricardo Benine, and it was the first representative of the genus Microglanis recorded from the upper rio Paraná basin — the drainage had previously been thought to lack the genus entirely. It belongs to the family Pseudopimelodidae, the dwarf and bumblebee catfishes, a group that was long lumped into Pimelodidae before molecular and morphological work split it out; older literature and some aggregator databases may still list Microglanis under the broader "Pimelodidae" umbrella, but Pseudopimelodidae is the currently accepted placement.
The species epithet honours Dr Julio Cesar Garavello, a Brazilian ichthyologist, in recognition of his contributions to the systematics of Neotropical fishes. The genus name Microglanis is Greek, from mikros ("small") and glanis (a name for a catfish), a fitting label for one of the smallest catfish genera in South America.
Morphology
Microglanis garavelloi is a genuinely tiny catfish: maximum recorded size is about 1.5 in standard length, and population studies found most individuals in the wild running smaller still, around 1 in SL, with an estimated asymptotic (theoretical maximum) length of only 1.5 in. Like other Microglanis it has the compact, big-headed "bumblebee catfish" silhouette, three pairs of barbels, and a short, deep body rather than the elongated shape of larger pimelodids.
As in virtually all catfishes the skin is naked and scaleless, which has direct consequences for medication sensitivity (see "In the aquarium"). Microglanis species carry the stiff, serrated pectoral spines typical of the group, which lock erect and can snag a soft aquarium net — small as this fish is, it should still be handled with a container rather than netted roughly.
Habitat
The species is endemic to the upper rio Paraná basin in Brazil, known specifically from tributaries of the rio Paranapanema and rio Tietê systems. It is described as a littoral-zone dweller of small rivers and streams rather than the main river channel, and appears to be the sole Microglanis representative in its watershed — an isolated, single-species presence rather than one of several co-occurring congeners as is typical elsewhere in the genus's range.
Dietary work on the species was carried out in a stream already described in the literature as disturbed, suggesting the fish can persist in at least moderately altered habitat, though this is not the same as saying it is tolerant of heavy degradation. Specific water chemistry readings for the type locality are not available from the sources consulted here; data is sparse on this point.
Feeding
Microglanis garavelloi is predominantly insectivorous, with a diet study finding a high frequency of Ephemeroptera — mayfly larvae, which themselves graze algae and biofilm on submerged surfaces — among stomach contents. The population was described as an opportunistic forager with considerable variation in diet between individual phenotypes, consistent with a small benthic predator taking whatever suitably sized invertebrate prey it encounters along the stream bed and margins.
No aquarium-specific feeding data exists for this species. Going by the broader pattern in nocturnal benthic catfishes and in related Microglanis, it would be expected to forage after dark for small invertebrates and to accept sinking pellets, frozen foods and similar prepared diets in captivity, offered once the lights are off so it is not out-competed by faster diurnal tankmates — but this is inference from the genus, not a documented observation for M. garavelloi itself.
Mating
Population biology work on Microglanis garavelloi found it to be a total spawner, releasing its eggs over a defined spawning period from October to February — the Southern Hemisphere spring through summer. Beyond the timing of spawning, no details of courtship or pairing behaviour have been documented for this species; data is sparse on this point and nothing here should be assumed to resemble the parasitic or internal-fertilisation strategies seen in other catfish groups.
Breeding
The same population study reports probable brood care in the form of male-guarding after spawning — the male apparently stays with the eggs or fry rather than the pair abandoning the clutch, though the study stops short of describing a nest structure. This pattern, combined with high fecundity, high mortality and low longevity and growth in the wild population, points to a short-lived, fast-turnover life history typical of small stream fishes under heavy predation pressure.
No aquarium breeding of Microglanis garavelloi has been documented in the sources available here. The species is not established in the ornamental trade, so — honestly — there is no home-aquarium breeding record to report; anyone attempting it would be working from the wild-population clues above (total spawning, a defined spring–summer window, and possible male brood-guarding) rather than from any existing hobbyist account.
In the aquarium
Microglanis garavelloi is not a fish most aquarists will ever encounter — it is not established in the ornamental trade, and specific care data for the species is essentially absent from the available literature. What can be said with confidence: at a maximum of roughly 1.5 in SL, and more typically 1 in in the wild, this is one of the smallest catfishes in the family, so there is no size trap here — the concern with this genus, if anything, is the opposite: a fish easily overlooked or out-competed in a busy tank.
As with all catfish it is scaleless-skinned and should be treated as medication-sensitive, meaning conservative dosing of copper-based treatments and many standard fish medications. It also carries the genus's typical locking pectoral spines, so it is best moved in a container rather than scooped in a net, even at this small size. Related Microglanis species (M. poecilus, M. iheringi) are reported as nocturnal, sheltering by day and emerging once acclimatised and fed, tolerant of ordinary tap water though softer, slightly acidic conditions are preferred for breeding, at temperatures around 72–82 °F — a reasonable starting point if this species were ever kept, though it should not be taken as confirmed data for M. garavelloi itself.
Conservation
The IUCN Red List assesses Microglanis garavelloi as Least Concern, with the assessment dated 2018, and FishBase records a low fishing/exploitation vulnerability score of 10 out of 100. As a narrow-range endemic restricted to tributaries of the rio Paranapanema and rio Tietê in the upper rio Paraná basin, its favourable status reflects a lack of documented major threats rather than a wide distribution — a species this geographically restricted still depends on the health of a specific set of small rivers, and the fact that dietary sampling was conducted in an already-disturbed stream is a reminder that its habitat is not free of human pressure. It is not part of the aquarium trade, so collection for the hobby is not a relevant threat for this species.