Otocinclus mariae

Otocinclus mariae is known from specimens collected in Bolivian and southern Brazilian river systems, placing it among the more centrally distributed members of the genus. It is a moderately sized Otocinclus with standard lateral striping and subtly reticulated dorsal patterning, closely resembling several other species in the genus and therefore often misidentified in the trade.

The habitat of O. mariae consists of clear, shallow streams and river margins with moderate flow, sandy substrates, and aquatic vegetation. In common with its congeners, it is a social grazer that feeds continuously on the periphyton community coating submerged objects. Its occurrence in both Bolivian and Brazilian drainages suggests tolerance of somewhat varied water conditions.

In the aquarium, O. mariae is an effective and unobtrusive algae manager best kept in groups of six or more. Its care is standard for the genus: soft to moderately hard water, a planted aquarium with established biofilm, and supplemental vegetable feeding. Like many Otocinclus from interior river systems, it adapts reasonably well to aquarium life once past the challenging initial acclimatisation phase.

Water: Soft to moderately hard at pH 6.0–7.5 and 20–26°C; pristine conditions during acclimatisation and maintained low nitrates thereafter. Tank: 40 litres minimum with live plants, driftwood, and smooth stones; moderate lighting supports natural algae growth. Feeding: Biofilm plus blanched courgette, cucumber, and algae wafers; supplement feeding daily until fish are fully established. Breeding: Uncommon in captivity; soft, slightly acidic water and conditioning with live foods may stimulate spawning. Compatibility: Peaceful with all small community species; ideal in a South American community with small tetras and corydoras.