Care guide · Freshwater · fish

Striped headstander

Anostomus anostomus

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Anostomus anostomus, the striped headstander, is a South American anostomid with an oblique swimming posture and a mouth adapted for grazing surfaces. The repeated genus and species name is correct, not a duplicate record. Despite the common name, individual fish do not necessarily hold one identical angle all the time. More important for care are oxygen-rich water, movement, grazing surfaces and a carefully selected social setup. Ask how the fish has acclimated and check that it actively grazes surfaces. Decide in advance whether a single fish or a large group fits your aquarium.

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At a glance

Temperature: 20–28 °C
pH: 5.5–7.5
GH: 1–18 °dGH
Aquarium length: At least 120 cm
Minimum aquarium volume: At least 108 L
Adult size: At least 20 cm
Group size: At least 6 individuals
Temperament: Territorial

About this species

Seriously Fish reports a maximum standard length of 200 mm. Standard length ends at the tail base and excludes the caudal fin, so this fish grows considerably larger than many medium-sized tetras. The specialist source gives a minimum footprint of 120 × 30 cm, about 108 litres at the stated height. Treat that as a source-specific minimum and provide extra room when the layout or companions require it.

Natural habitat

Eschmeyer and Seriously Fish report the species from the Amazon and Orinoco systems, including areas of Brazil, Ecuador, Colombia, Guyana, Peru and Suriname. In nature it lives along rocky shores of fast-flowing rivers, grazing algae and small invertebrates from surfaces. This supports an aquarium with oxygen, water movement and grazing areas; it does not mean every tank must reproduce one exact river habitat.

Aquarium and layout

Seriously Fish gives 120 × 30 cm as the smallest footprint and about 108 litres at its reference height. Provide well-aerated water with noticeable movement, smooth rocks or other safe surfaces for biofilm, and open swimming room. A tight-fitting cover is essential because headstanders jump. Plants may be used, but the fish may graze on them. Keep one specimen or six or more in a larger aquarium; small groups are more prone to conflict.

Water conditions

The specialist profile gives 20–28°C, pH 5.5–7.5 and GH 1–18 dGH. These broad ranges are not an invitation to shift abruptly between extremes. Keep temperature and chemistry stable, maintain oxygenation, and prevent organic waste from accumulating. Acclimate new fish gradually to the aquarium. Measure water values rather than guessing them from geographic origin.

Behaviour and group size

This species can be territorial and, according to the specialist profile, quarrelsome when only a few conspecifics are kept. Choose one specimen or at least six in a larger tank. Medium-to-large peaceful fish may work when swimming zone, feeding and behaviour fit. Much smaller species may be eaten. Watch for repeated chasing, fin damage and whether every fish can reach food and grazing surfaces.

Feeding

Anostomus anostomus is an omnivorous grazer. In the wild it takes algae, insect larvae and other small items from surfaces. In aquaria, offer suitable small frozen or live foods alongside generous vegetable matter, such as blanched greens and algae foods. Keep safe grazing surfaces available. Rotate foods, avoid overfeeding and remove leftovers to maintain water quality.

Breeding

The species profile says reliable aquarium-breeding information is very scarce. It mentions commercial breeding in South America and Asia but gives no repeatable home method. This guide therefore does not invent a temperature trigger, egg count, parental care or larval diet. Stable conditions and good nutrition support condition but do not guarantee reproduction. Consider the aquarium size and social setup when observing any breeding behaviour.

Sources & review

This care guide draws on several specialist sources and was last checked on 16 October 2026.

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