Otocinclus vittatus
Best biofilm/algae eater for planted tanks. Only add to a tank with established biofilm and soft green algae. Sensitive to stress, acclimate slowly.
Otocinclus (Common) (Otocinclus vittatus) reaches 3.5–5 cm as an adult and needs a minimum tank of 60 L. Native to Northern and central South America, it lives in the bottom (grazes everywhere) water column with a peaceful temperament. Aim for 20–26 °C, pH 6.0–7.5, and 2–10 dGH hardness. Lifespan is 3–5 years with good care. Keep otocinclus (common) in groups of 6+, yes schoolers need numbers to display natural behaviour. Diet: herbivore (algae), Soft green algae, blanched zucchini, courgette, Repashy Soilent Green. Will starve in a clean new tank. Plant-safe: Yes. Shrimp-safe: Yes.
Care at a glance
Best biofilm/algae eater for planted tanks. Only add to a tank with established biofilm and soft green algae. Sensitive to stress, acclimate slowly.
By Mike ElmiraUpdated 2 min read
Part of our complete guide to aquarium fish for the planted tank.
The parameters that decide whether otocinclus (common) fits in your tank.
Bottom (grazes everywhere)
Yes
Group of 6+
Loricariidae
Herbivore (algae)
Soft green algae, blanched zucchini, courgette, Repashy Soilent Green. Will starve in a clean new tank.
3–5 yrs
Very hard (rarely bred in captivity)
Slow vegetated streams of the Amazon basin
Northern and central South America
Tank-mate safety and the species this one is documented to thrive (or fail) alongside.
Every peaceful community fish in this list. They ignore everything and everything ignores them.
Larger cichlids, aggressive bottom-dwellers, any predatory fish.
Hard-won lessons from the tank.
Add otos only after 8–10 weeks of tank maturity, when soft green film is visible on glass. Buy 6+ from a single store, observe them eating in the shop before purchase. Acclimate over 90+ minutes.
'Otocinclus' = 'small mouthed', referring to the suckermouth.
What can go wrong and how to spot it.
Failure modes, in order of how dramatic the fix is.
Notoriously fragile in transport. The 'oto wasted away' phenomenon is real — they often arrive starving and acclimation deaths in week 1–2 are common.
Not a 'starter algae crew' fish — they need a tank with mature biofilm. New tanks kill them. Also: they don't eat hair algae or black beard algae. They eat diatoms (brown algae) and soft green film.
The practical routine, read top to bottom.
60 L+ planted tank that has been running for 2+ months (needs established biofilm). Soft to moderate flow. Sand substrate. Driftwood for grazing surface.
4 weeks in a planted, biofilm-rich QT — paradoxically a sterile bare QT can starve them. Offer Repashy Soilent Green and blanched zucchini immediately.
Where it comes from, how it behaves, and the variants you'll see at retail.
Where it lived before it came home.
Slow-moving streams across northern and central South America. Water tends to be soft to moderate, well-oxygenated, with abundant algae-covered submerged surfaces.
Soft green algae (especially diatoms), biofilm, occasional micro-invertebrates.
Population pressure exists from collection. Look for 'tank-bred' tags when available; pay the premium.
How they pair, reproduce, and grow.
Females are noticeably larger and rounder than males. Otherwise nearly identical.
Captive-bred individuals exist but are rare. Eggs laid on smooth surfaces (broad leaves, glass). Most stock is wild-caught from Brazil.
The named cultivars and the lookalikes worth flagging.
Several Otocinclus species enter the trade often labelled simply 'oto' — O. vittatus is most common; O. cocama (zebra oto), O. macrospilus, O. vestitus also appear.
Direct answers to the questions search engines and AI assistants surface most often about this species.
Otocinclus (Common) (Otocinclus vittatus) needs a minimum tank of 60 L. They live in the bottom (grazes everywhere) water column and should be kept in groups of 6+, so a longer footprint matters more than depth.
Target 20–26 °C, pH 6.0–7.5, and 2–10 dGH hardness. Acclimate slowly when moving them between water sources.
Shrimp safety: Yes. Plant safety: Yes.
Otocinclus (Common) are herbivore (algae). Soft green algae, blanched zucchini, courgette, Repashy Soilent Green. Will starve in a clean new tank.
On Fin & Stem's 1–5 difficulty scale this species rates 3/5. Intermediate, stable parameters and a mature tank matter. Breeding difficulty: very hard (rarely bred in captivity).
Typical lifespan in a well-maintained tank is 3–5 years.
A planted tank is a system. Pair this fish with one entry from each other pillar to plan the whole scape.
