Taxonomy & naming
Puntigrus tetrazona was described by the Dutch ichthyologist Pieter Bleeker in 1855 from Sumatra, originally in the genus Capoeta and long carried under Barbus and then Puntius. The Catalog of Fishes (Eschmeyer, the authority for valid names) records the valid combination as Puntigrus tetrazona (Bleeker, 1855), the parenthetical authority marking the move out of Bleeker's original genus.
The genus Puntigrus was erected by Kottelat in 2013 to hold the "tiger barbs" — a tight cluster of banded species pulled out of the old catch-all Puntius. Several look-alikes are involved: P. anchisporus from Borneo, P. partipentazona from the mainland (Indochina), and P. navjotsodhii, alongside P. tetrazona itself. Because aquarium stock has been line-bred and moved for decades, the fish sold as "tiger barb" is not always assignable to a single wild species, and older aquarium literature uses the name tetrazona for the whole group. Here it follows the current Catalog of Fishes placement for the Sumatran and Bornean species.
Morphology
The tiger barb is a small, deep- and short-bodied barb reaching about 3 in in total length, with the high-backed, laterally compressed shape typical of the group. The ground colour is a pale silvery to brassy gold, crossed by four vertical black bars: one through the eye, one behind the gill cover, one at mid-body above the pelvic fins, and one across the caudal peduncle. The snout, the leading edge of the dorsal fin and the lower fins are flushed with orange to red, brightest in dominant fish.
The species is moderately sexually dimorphic. Males are smaller and slimmer, with more intense red on the snout and fins; females are larger and become visibly rounder when carrying eggs. A number of fixed aquarium colour forms exist — "green" (melanistic), albino, and long-finned strains among them — all selectively bred from the same stock rather than representing distinct wild populations.
Habitat
Puntigrus tetrazona is native to the lowland fresh waters of Sumatra and Borneo in the Greater Sunda Islands, where it lives in clear and slightly tannin-stained forest streams and the quieter margins of rivers, typically over sand or leaf litter and among submerged wood and vegetation. It is a benthopelagic, schooling fish of warm, soft to moderately hard water.
FishBase gives a pH range of roughly 6–8 and a hardness of about 5–19 dGH for the species, consistent with the soft, mildly acidic to neutral blackwater and clearwater habitats of Sundaland. Water temperatures across the range are tropical, broadly in the low-to-mid twenties Celsius. The tiger barb has been introduced and established in a number of warm regions outside its native range through the aquarium trade, including parts of the Americas and Southeast Asia.
Feeding
The tiger barb is an omnivore. In the wild it takes small invertebrates — insect larvae, crustaceans and worms — along with algae, plant matter and organic detritus picked from the substrate and the water column. Its short, deep body and constant activity suit a fish that grazes and snaps at small prey throughout the day rather than ambushing it.
In the aquarium it is undemanding and accepts virtually all standard foods: good-quality flakes and small pellets, supplemented with live and frozen items such as bloodworm, brine shrimp and daphnia, and some vegetable matter. A varied diet keeps the red and orange pigment strong. The species' eager, fast feeding is part of why it can dominate slower tankmates at mealtimes.
Mating
Like the great majority of barbs, the tiger barb is an egg-scattering, non-guarding spawner with no nest and no parental care. Spawning is triggered by warmth and good condition, often after a few days of generous feeding on live foods. A ready male drives a gravid female through fine-leaved plants or over the substrate, the two pressing together briefly as eggs and milt are released.
There is no pair bond beyond the act of spawning, and no territory is held except transiently during courtship. Colour and activity peak at this time, with dominant males at their reddest as they compete to drive females. The eggs are adhesive and fall among plants or onto the bottom, where — left to the adults — they are promptly eaten.
Breeding
Tiger barbs are readily bred in aquaria and are a common first egg-layer for hobbyists. A typical method uses a separate shallow spawning tank with soft, slightly acidic water, fine-leaved plants or a spawning mop, and a mesh or marble layer on the bottom so that the scattered eggs fall out of the parents' reach. A well-conditioned pair or small group is introduced, and spawning usually follows in the morning.
A female may release a few hundred adhesive eggs in a session. The adults eat eggs and fry given the chance, so they are removed after spawning. Eggs hatch in roughly a day to a day and a half at tropical temperatures, and the larvae become free-swimming a few days later, when they are fed infusoria and then newly hatched brine shrimp. Growth is rapid, and the species' hardiness and high fecundity have made the various ornamental strains easy to maintain in the trade.
In the aquarium
The tiger barb is a hardy, inexpensive and widely available aquarium fish, but it is best understood as a shoaling species with a strong internal pecking order. Kept singly or in twos and threes it becomes nervous and turns its harassment on tankmates — the origin of its fin-nipping reputation — whereas a group of at least six to ten, and ideally more, keeps that behaviour within the school. Long-finned and slow tankmates such as bettas, angelfish and guppies are poor companions for the same reason.
It suits a roomy tank with open swimming space, some planting and steady, well-filtered water in the low-to-mid twenties Celsius, with a broadly neutral pH and soft-to-moderate hardness reflecting its Sundaland origins. Good tankmates are other active, robust mid-water fishes of similar temperament. The species is omnivorous and easy to feed, tolerant of a range of conditions, and long-lived for a small barb when well kept.
Conservation
Puntigrus tetrazona is listed as Least Concern (LC) on the IUCN Red List, assessed on 13 April 2020. It is a widespread species across Sumatra and Borneo with no evidence of major range-wide decline, and the overwhelming majority of fish in the aquarium trade are captive-bred rather than wild-caught, which limits collection pressure on wild populations.
As with much of the Sundaland freshwater fauna, the principal long-term concerns are habitat-based — deforestation, drainage of peat swamps, and pollution of lowland rivers in Sumatra and Borneo — rather than direct exploitation. The species' adaptability and its established presence in the ornamental trade give it a measure of security that many narrower-ranging Sundaic fishes lack.