Taxonomy & naming
Tanichthys micagemmae was described by the German ichthyologists Jörg Freyhof and Fabian Herder in 2001, from streams in northern Vietnam. It belongs to the family Danionidae, within the small genus Tanichthys, alongside the type species T. albonubes and the more recently reassigned Alligarina thacbaensis (originally described in Tanichthys). The Catalog of Fishes (Eschmeyer, California Academy of Sciences) treats Tanichthys micagemmae as the valid combination.
The genus name Tanichthys combines the surname of Tan Kam-fei — the Boy Scout credited with first collecting the type species, T. albonubes, on White Cloud Mountain around 1930 — with the Greek ichthys (fish); this is a genus-level note, not a description-specific detail for T. micagemmae itself. The species epithet micagemmae most plausibly derives from Latin roots evoking a shimmering or gem-like appearance (compare micans, 'shining, glittering,' and gemma, 'bud, jewel'), fitting the fish's iridescent colouration, though the exact intended derivation and any personal dedication in the original description were not confirmed for this article. Approximate pronunciation: tan-IK-thiss my-ka-JEM-eye.
Morphology
Tanichthys micagemmae shares the general slender, torpedo-shaped body plan of its genus, reaching a similarly small adult size to T. albonubes. It is generally described as showing a more pronounced orange-to-red colouration in the fins and a more golden or greenish body sheen than the type species, though a full, sourced morphometric comparison was not accessible for this article. As in T. albonubes, males are expected to show more intense fin colour than females.
Habitat
Tanichthys micagemmae is native to hill streams in northern Vietnam, occupying a habitat broadly similar to that of T. albonubes — clear, cool, well-oxygenated streams at moderate elevation. Its known range is considerably more restricted than that of the type species, and specific drainage and water-chemistry data beyond this general description were not accessible for this article.
Feeding
No dedicated dietary study for Tanichthys micagemmae was accessible for this article. By analogy with T. albonubes and other small danionins, it is expected to be an omnivore taking small aquatic invertebrates, insect larvae, and algae or plant material in the wild, and to accept flake, micro-pellet and live/frozen foods readily in the aquarium — a genus-level inference rather than a documented finding for this species specifically.
Mating
Specific courtship behaviour for Tanichthys micagemmae was not accessible for this article. By analogy with T. albonubes, males are expected to be more slender and more intensely coloured than females, with courtship consisting of display and chasing through vegetation typical of egg-scattering cyprinids.
Breeding
Dedicated breeding accounts for Tanichthys micagemmae in the aquarium are less common than for the widely bred T. albonubes, but by genus-level analogy it is expected to be a continuous egg-scatterer among fine-leaved plants or spawning mops, with no parental care and a tendency for adults to eat their own eggs and fry. This is inferred from the genus pattern rather than confirmed by a dedicated account for this species.
In the aquarium
Tanichthys micagemmae appears occasionally in the specialist hobby as a less common alternative to the ubiquitous White Cloud Mountain minnow. By genus-level analogy it is expected to be a hardy, peaceful schooling fish suited to cooler, unheated or lightly heated planted aquaria and community setups with other small, peaceful fish, kept in groups, though dedicated husbandry accounts specific to this species were not accessible for this article.
Conservation
Tanichthys micagemmae carries a CARES Fish Preservation Program priority listing of Vulnerable (CVU), reflecting its comparatively restricted range in northern Vietnam relative to the widespread and heavily captive-bred T. albonubes. A current IUCN Red List category was not confirmed for this article, and specific population trend or threat data for this species were not accessible here; habitat degradation and stream pollution affecting Vietnamese hill-stream fish generally would be expected to be relevant pressures.