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Care guide · Freshwater · fish

Six-banded barb

Desmopuntius hexazona

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The six-banded barb (Desmopuntius hexazona) is often sold under the misleading trade name pentazona barb. It closely resembles D. pentazona but is a separate species. D. pentazona has a small dark mark at the rear of the dorsal-fin base; D. hexazona lacks it. Since many trade fish are mislabelled, the shop name cannot confirm identity. Seriously Fish lists 55 mm standard length, a minimum 80 × 30 cm base and about 72 litres. Keep a shoal of at least eight to ten in soft, acidic water.

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At a glance

Temperature
20–26 °C
pH
4.0–7.0
GH
1–5 °dGH
Aquarium length
At least 80 cm
Minimum aquarium volume
At least 72 L
Adult size
Up to 5.5 cm
Group size
At least 8–10 individuals
Temperament
Peaceful

About this species

Desmopuntius hexazona was described by Weber and de Beaufort in 1912. Former combinations include Barbus hexazona and Systomus hexazona. The name pentazona barb is widely used for this species but should not be treated as reliable identification. D. hexazona is closely related to D. pentazona; the latter has a small dark mark near the rear of the dorsal-fin base. The former name Puntius johorensis was misapplied to D. hexazona and is not a reason to merge it with D. johorensis.

Natural habitat

The species occurs in parts of southern Borneo, eastern Sumatra, Singapore and the Malay Peninsula. It mainly inhabits peat swamps, blackwater streams and other still waters, often among submerged grasses and dense riparian vegetation. The water is humic-stained, mineral-poor and can be naturally very acidic. In Singapore, the population is described as highly endangered and restricted to the Central Catchment Nature Reserve; this is a local statement, not a global Red List assessment.

Aquarium and layout

Provide at least an 80 × 30 cm base and about 72 litres for a shoal of eight to ten. Add cover with roots, branches, leaf litter and plants while preserving swimming room. Subdued light and soft substrate suit blackwater conditions. Strong flow is unnecessary. Keep very soft water clean and stable. Do not identify trade fish from the pentazona label alone; check diagnostic features and ask about provenance where possible.

Water conditions

Seriously Fish recommends 20–26 °C, pH 4.0–7.0 and GH 1–5 dGH. This fish needs soft, acidic water. Keep parameters stable and do not adjust pH suddenly; chemical correction can be dangerous. Low pH in natural blackwater is not a reason to pursue extreme aquarium values without a monitoring and maintenance plan. Choose tankmates that can live long-term at similar temperatures and softness.

Behaviour and group size

The six-banded barb is a shoaling fish; keep at least eight to ten. Avoid boisterous or very vigorous companions that can outcompete it for food. Assess combinations by adult size, activity, water needs and feeding access. D. pentazona is a separate, similar-looking species; do not link the two automatically based only on shop names or appearance. No individually verified species pairs are linked here, so compatibility is not invented from water overlap.

Feeding

This barb is a micropredator that eats small insects, worms, crustaceans and zooplankton. It accepts suitable dried food, but this should not make up the entire diet. Offer small portions of complete food and vary with suitable live or frozen prey such as Daphnia and Artemia. Provide variety and ensure quieter fish can get enough food.

Breeding

The six-banded barb scatters eggs and provides no parental care. For breeding, use a separate dimly lit tank with an egg grid, marbles, fine-leaved plants or spawning mops. Remove adults after spawning because they may eat eggs. Seriously Fish reports hatching in 24–36 hours and free swimming after three to four days; start with infusoria-grade food.

Sources & review

This care guide draws on several specialist sources and was last checked on .

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