Photo: Carl H. Eigenmann / Waldo Lee McAtee (Public domain) — via Wikimedia Commons
Otocinclus (Otocinclus vittatus)
A thumbnail-sized algae vacuum that keeps plant leaves spotless — provided the tank is mature and you buy at least six.
Will it live with a Otocinclus?
We compare each fish against your otocinclus on temperament, size, water parameters and swimming zone. Set your tank size and filter the results.
- African Dwarf Frog✅ CompatiblePeaceful · 4 cm · Medium care · 22–26 °C (72–79 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Amapá Tetra✅ CompatiblePeaceful · 4 cm · Medium care · 24–27 °C (75–81 °F)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Amapá Tetra in a shoal of 6+ or it gets stressed and nippy.
- Black Darter Tetra✅ CompatibleSemi-aggressive · 4 cm · Hard care · 21–28 °C (70–82 °F)
- Compatible on the things that matter: shared water near 21–26 °C, workable temperaments, and no predator-and-prey size gap.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Blue Danio✅ CompatiblePeaceful · 4 cm · Easy care · 21–26 °C (70–79 °F)
- Both are peaceful, and their water overlaps around 21–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Blue Danio in a shoal of 6+ or it gets stressed and nippy.
- Blue Emperor Tetra✅ CompatiblePeaceful · 4 cm · Medium care · 23–27 °C (73–81 °F)
- Both are peaceful, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Blue Emperor Tetra in a shoal of 6+ or it gets stressed and nippy.
- Cardinal Tetra✅ CompatiblePeaceful · 4 cm · Medium care · 23–27 °C (73–81 °F)
- Both are peaceful, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Cardinal Tetra in a shoal of 6+ or it gets stressed and nippy.
- Emperor Tetra✅ CompatiblePeaceful · 4 cm · Easy care · 23–27 °C (73–81 °F)
- Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Emperor Tetra in a shoal of 6+ or it gets stressed and nippy.
- Flame Tetra✅ CompatiblePeaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Flame Tetra in a shoal of 6+ or it gets stressed and nippy.
- Ghost Shrimp✅ CompatiblePeaceful · 4 cm · Easy care · 18–28 °C (64–82 °F)
- Both are peaceful, and their water overlaps around 21–26 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Ghost Shrimp in a shoal of 6+ or it gets stressed and nippy.
- Glowlight Tetra✅ CompatiblePeaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Glowlight Tetra in a shoal of 6+ or it gets stressed and nippy.
- Golden Dwarf Barb✅ CompatiblePeaceful · 4 cm · Easy care · 18–24 °C (64–75 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Golden Dwarf Barb in a shoal of 6+ or it gets stressed and nippy.
- Jelly Bean Tetra✅ CompatiblePeaceful · 4 cm · Medium care · 20–26 °C (68–79 °F)
- Both are peaceful, and their water overlaps around 21–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Jelly Bean Tetra in a shoal of 10+ or it gets stressed and nippy.
- Marbled Hatchetfish✅ CompatiblePeaceful · 4 cm · Medium care · 23–28 °C (73–82 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Marbled Hatchetfish in a shoal of 6+ or it gets stressed and nippy.
- Phoenix Tetra✅ CompatiblePeaceful · 4 cm · Easy care · 23–28 °C (73–82 °F)
- Compatible on the things that matter: shared water near 23–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Phoenix Tetra in a shoal of 8+ or it gets stressed and nippy.
- Purple Tetra✅ CompatiblePeaceful · 4 cm · Medium care · 22–26 °C (72–79 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Purple Tetra in a shoal of 8+ or it gets stressed and nippy.
- Red Phantom Tetra✅ CompatiblePeaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
- Compatible on the things that matter: shared water near 22–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Red Phantom Tetra in a shoal of 8+ or it gets stressed and nippy.
- Rosy Tetra✅ CompatiblePeaceful · 4 cm · Easy care · 22–28 °C (72–82 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Rosy Tetra in a shoal of 6+ or it gets stressed and nippy.
- Rummy Nose Rasbora✅ CompatiblePeaceful · 4 cm · Medium care · 20–26 °C (68–79 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Rummy Nose Rasbora in a shoal of 8+ or it gets stressed and nippy.
- Serpae Tetra✅ CompatibleSemi-aggressive · 4 cm · Easy care · 23–28 °C (73–82 °F)
- Peaceful + Semi-aggressive, but with no direct clash here, and their water overlaps around 23–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Serpae Tetra in a shoal of 6+ or it gets stressed and nippy.
- Sparkling Gourami✅ CompatiblePeaceful · 4 cm · Medium care · 24–28 °C (75–82 °F)
- Compatible on the things that matter: shared water near 24–26 °C, workable temperaments, and no predator-and-prey size gap.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Strawberry Betta✅ CompatiblePeaceful · 4 cm · Medium care · 22–27 °C (72–81 °F)
- Both are peaceful; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Threadfin Rainbowfish✅ CompatiblePeaceful · 4 cm · Medium care · 24–28 °C (75–82 °F)
- Both are peaceful, and their water overlaps around 24–26 °C — no size, zone or temperament conflicts.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Threadfin Rainbowfish in a shoal of 6+ or it gets stressed and nippy.
- Tiger Badis✅ CompatibleSemi-aggressive · 4 cm · Medium care · 22–24 °C (72–75 °F)
- Peaceful + Semi-aggressive, but with no direct clash here; temperature, pH and hardness ranges all overlap and neither outsizes the other enough to be a threat.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Tiger Otocinclus✅ CompatiblePeaceful · 4 cm · Medium care · 22–27 °C (72–81 °F)
- Both are peaceful, and their water overlaps around 22–26 °C — no size, zone or temperament conflicts.
- Both favour the bottom of the tank — offer enough cover so they aren't always in each other's space.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Tiger Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- African Butterfly Cichlid⚠️ With cautionSemi-aggressive · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Amazon Puffer⚠️ With cautionPeaceful · 8 cm · Medium care · 23–28 °C (73–82 °F)
- Your 75 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Amazon Puffer in a shoal of 6+ or it gets stressed and nippy.
- Ash Lipped Apisto⚠️ With cautionSemi-aggressive · 7 cm · Hard care · 24–29 °C (75–84 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Black Ruby Barb⚠️ With cautionSemi-aggressive · 6 cm · Easy care · 22–26 °C (72–79 °F)
- Your 75 L tank is below the ~100 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Black Ruby Barb in a shoal of 6+ or it gets stressed and nippy.
- Bleeding Heart Tetra⚠️ With cautionSemi-aggressive · 7 cm · Medium care · 23–28 °C (73–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Bleeding Heart Tetra in a shoal of 6+ or it gets stressed and nippy.
- Bright Diamond Tetra⚠️ With cautionPeaceful · 7 cm · Hard care · 24–28 °C (75–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Bright Diamond Tetra in a shoal of 8+ or it gets stressed and nippy.
- Buenos Aires Tetra⚠️ With cautionSemi-aggressive · 7 cm · Easy care · 18–26 °C (64–79 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Buenos Aires Tetra in a shoal of 6+ or it gets stressed and nippy.
- Colombian Tetra⚠️ With cautionSemi-aggressive · 6.5 cm · Easy care · 24–28 °C (75–82 °F)
- Your 75 L tank is below the ~114 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Colombian Tetra in a shoal of 6+ or it gets stressed and nippy.
- Congo Tetra⚠️ With cautionPeaceful · 8 cm · Medium care · 22–28 °C (72–82 °F)
- Your 75 L tank is below the ~120 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Congo Tetra in a shoal of 6+ or it gets stressed and nippy.
- Dwarf Chain Loach⚠️ With cautionPeaceful · 6 cm · Medium care · 24–29 °C (75–84 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Dwarf Chain Loach in a shoal of 6+ or it gets stressed and nippy.
- Glass Catfish⚠️ With cautionPeaceful · 8 cm · Medium care · 23–28 °C (73–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Glass Catfish in a shoal of 6+ or it gets stressed and nippy.
- Humpbacked Tetra⚠️ With cautionSemi-aggressive · 5 cm · Hard care · 24–28 °C (75–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Humpbacked Tetra in a shoal of 8+ or it gets stressed and nippy.
- Melon Barb⚠️ With cautionPeaceful · 7 cm · Easy care · 22–28 °C (72–82 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Melon Barb in a shoal of 8+ or it gets stressed and nippy.
- Morse Code Corydoras⚠️ With cautionPeaceful · 5 cm · Medium care · 23–26 °C (73–79 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Morse Code Corydoras in a shoal of 6+ or it gets stressed and nippy.
- Rounded Filament Barb⚠️ With cautionPeaceful · 7 cm · Medium care · 22–27 °C (72–81 °F)
- Your 75 L tank is below the ~80 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Rounded Filament Barb in a shoal of 6+ or it gets stressed and nippy.
- Tiger Barb⚠️ With cautionSemi-aggressive · 7 cm · Easy care · 22–28 °C (72–82 °F)
- Your 75 L tank is below the ~95 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Tiger Barb in a shoal of 6+ or it gets stressed and nippy.
- Discus⛔ Not recommendedPeaceful · 20 cm · Hard care · 28–31 °C (82–88 °F)
- Temperature needs don't overlap (Otocinclus 21–26 °C vs Discus 28–31 °C).
- Your 75 L tank is below the ~200 L this pairing really wants — crowding raises aggression.
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
- Keep Discus in a shoal of 6+ or it gets stressed and nippy.
- German Blue Ram⛔ Not recommendedPeaceful · 6 cm · Hard care · 27–30 °C (81–86 °F)
- Temperature needs don't overlap (Otocinclus 21–26 °C vs German Blue Ram 27–30 °C).
- Keep Otocinclus in a shoal of 6+ or it gets stressed and nippy.
Compatibility is computed from each species' care data — a strong starting point, not a guarantee. Individual temperament varies, so always introduce new fish slowly and watch them.
Otocinclus care specs
- Care level
- Medium
- Breeding
- Hard
- Max size
- 4 cm (1.6 in)
- Min tank size
- 60 L (15.9 gal)
- Temperature
- 21–26 °C (70–79 °F)
- pH
- 6–7.5
- Hardness
- 2–12 dGH
- Lifespan
- 3–5 years
- Diet
- Herbivore
- Swim level
- Bottom
- Group size
- 6+ (shoaling)
- Family
- Loricariidae
- Origin
- South America — Amazon and Paraná river basins (Brazil, Bolivia, Paraguay, Argentina)
What is an otocinclus?
The otocinclus (Otocinclus vittatus) is a miniature loricariid catfish from South America, reaching a maximum of just 4 cm (1.6 in) at adulthood. Despite its modest size, it punches well above its weight as an algae-management tool: a small group will methodically graze the soft green film from glass panels, plant leaves, and smooth hardscape in ways that larger algae-eaters cannot match without disturbing the tank. They belong to the family Loricariidae — the armoured suckermouth catfish — and share the distinctive underslung mouth and bony scutes of their larger relatives.
Otocinclus are peaceful, active during the day, and extremely well-suited to community planted tanks. They do, however, have a genuine care-level of Medium: their dependence on an established biofilm and their fragility at import make them a fish that rewards preparation rather than impulse buying. Get the conditions right before purchasing, and they are among the most rewarding small catfish available.
Where do otocinclus come from?
Wild otocinclus inhabit the Amazon and Paraná river basins, ranging across Brazil, Bolivia, Paraguay and Argentina. They are found in shallow, slow-to-moderately-flowing streams and river margins where sunlight reaches the bottom and promotes rich algal growth on submerged rocks, roots and vegetation. The water in these habitats is typically soft and slightly acidic, shaded by overhanging vegetation, with abundant cover in the form of leaf litter and driftwood.
Almost all otocinclus sold in the hobby are wild-caught rather than tank-bred, which directly explains why they arrive stressed and undernourished. Replicating their natural conditions — mature water, gentle flow, and plentiful grazing surface — is the single most important thing you can do to keep them alive.
What size tank does an otocinclus need?
The minimum recommended tank size is 60 litres (16 gallons). This accommodates a group of six — the minimum social unit for a schooling species — while providing enough surface area for meaningful algae growth and enough water volume to maintain stable parameters. Larger tanks of 80–120 L (21–32 gal) are better still: more glass and hardscape means more grazing territory, and higher water volume buffers temperature and chemistry swings.
Tank shape matters. A long, shallow footprint provides more grazing surface than a tall, narrow column. Otocinclus hug the bottom and sides; they rarely venture far from surfaces. Densely planted tanks with broad-leaved plants like anubias and amazon swords are ideal, since each leaf becomes a grazing station. Driftwood adds tannins that soften the water slightly and surfaces for biofilm to colonise. Keep the filter turnover moderate — a gentle current suits them far better than a powerful powerhead.
What water parameters do otocinclus need?
- Temperature: 21–26 °C (70–79 °F) — they prefer the cooler end of the tropical spectrum.
- pH: 6.0–7.5, soft to neutral.
- Hardness: 2–12 dGH; softer water is closer to their natural habitat.
Consistency is more important than precision. Otocinclus tolerate a modest range of parameters but are sensitive to sudden changes, ammonia spikes, and nitrite — their small body mass leaves little buffer against poor water quality. The tank must be fully cycled before they are introduced. Aim to keep nitrates below 20 ppm with weekly partial water changes. Avoid treating the tank with copper-based medications while otos are present; like all scaleless and lightly armoured fish, they are unusually sensitive to copper.
What do otocinclus eat?
Otocinclus are herbivores that graze almost continuously on soft green algae — the thin biofilm that coats glass, plant surfaces and smooth stones. This is not optional grazing; it is their primary nutrition, and a tank that cannot sustain a constant supply will starve them. Introduce otos only to a tank that has been running for at least four to six months with visible green algae on surfaces.
Supplement grazing with:
- Blanched vegetables — zucchini (courgette), cucumber and spinach are all accepted; slice thinly, blanch briefly, and weigh down with a clip or fork.
- Algae wafers — choose a brand with spirulina or kelp high in the ingredient list; leave a small piece in the tank overnight.
- Biofilm — a piece of aged driftwood or a mature ceramic decoration introduced from another established tank gives them an immediate food source.
Remove uneaten vegetable matter after 24 hours to avoid fouling the water. Otos will not eat protein-heavy foods, so standard fish flakes and pellets are not a substitute for algae-based fare.
Are otocinclus aggressive — and what fish can live with them?
Otocinclus are among the most peaceful fish in the freshwater hobby — completely non-aggressive toward any tank-mate and indifferent to territory. The compatibility concern runs entirely in the other direction: their small size (4 cm / 1.6 in) makes them vulnerable to anything large or predatory enough to eat them.
Good tank-mate groups include:
- Small tetras (neon, ember, cardinal, rummy-nose)
- Small rasboras (chili rasboras, harlequin rasboras)
- Corydoras catfish (occupy a similar zone but do not compete)
- Dwarf gouramis and honey gouramis
- Peaceful dwarf cichlids (rams, apistogrammas in a larger tank)
- Freshwater shrimp (cherry shrimp, amano shrimp) — otos ignore invertebrates entirely
Avoid cichlids that are large or aggressive, any fish that exceeds roughly 10 cm (4 in) with a predatory temperament, and fin-nippers that may harass the otos’ soft, unprotected belly. Goldfish should be avoided as their temperature range (cooler) and heavy bioload are unsuitable companions.
For a full compatibility breakdown, see Otocinclus tank mates.
How do you tell male and female otocinclus apart?
Sexual dimorphism in otocinclus is subtle except when females are carrying eggs. Females are noticeably rounder and broader-bodied when gravid, and viewed from above they are conspicuously wider across the abdomen than males. Outside of breeding condition the difference is less pronounced, but females generally retain a slightly fuller body profile. Males are slimmer, with a more streamlined silhouette when viewed dorsally. In a group of six or more, the variation in body shape usually makes it possible to pick out likely females, though precise sexing of juveniles is difficult.
How do otocinclus breed?
Otocinclus breeding in captivity is rated Hard and rarely happens by accident. When it does occur, it tends to follow a period of conditioning on varied vegetable matter and a modest temperature fluctuation that mimics the wet-season trigger of their natural habitat.
The typical sequence: a male pursues a female persistently; the pair adopts a T-position (similar to corydoras) during which eggs are fertilised; the female then deposits small, adhesive egg clusters on the glass or plant leaves. The eggs hatch in roughly two to three days at 24–25 °C (75–77 °F), and the tiny fry initially feed on the same biofilm as the adults.
Raising fry successfully is the difficult part. They are minuscule and need a near-continuous supply of soft green algae and powdered spirulina. Dedicated breeders set up a small, heavily lighted tank specifically to cultivate algae for the fry. The adults do not actively guard the eggs and will not eat them, but fry benefit from being raised separately from larger tank-mates. Reliable, repeatable breeding results are uncommon outside specialist circles.
What are common otocinclus diseases?
The most frequent health problems in otocinclus are:
- Starvation / emaciation — the most common cause of death, particularly in newly purchased fish. The belly appears concave or “pinched.” Prevention is ensuring a mature, algae-rich tank and immediate supplemental feeding.
- White spot (ich) — small white dots on the skin and fins; caused by temperature stress or introduction of infected fish. Quarantine new additions and keep temperatures stable to prevent outbreaks.
- Bacterial infections — ragged fins, ulcers or patchy discolouration often follow stress, physical damage or poor water quality. Maintain clean water and avoid sudden parameter swings.
- Internal parasites — wild-caught otos occasionally arrive with internal parasites, which can cause wasting despite apparent feeding. A preventative quarantine period with observation is good practice.
Prevention is straightforward in principle: a cycled tank, stable water quality, correct nutrition, and a quarantine period for all new fish. Otocinclus are small-bodied and can deteriorate quickly, so act on any sign of ill health promptly.
Health note: medication dosing and disease identification are beyond the scope of a care profile. For unwell fish, confirm symptoms against a reputable veterinary or fish-health source before medicating — and note that many medications formulated for other fish are harmful to loricariids.
How long do otocinclus live?
A well-kept otocinclus lives 3–5 years. Given that most die within weeks of purchase due to starvation, reaching that lifespan is a meaningful benchmark — one that reflects a tank set up with their needs in mind from the start. Otos that survive the critical first month and find a stable food supply typically prove hardy and long-lived within their size class. Keep the group intact; isolated individuals age poorly compared to those kept with conspecifics.
Frequently asked questions
Why do otocinclus keep dying after I bring them home?
Nearly all newly imported otos arrive half-starved: they graze constantly in the wild, and holding tanks at wholesalers rarely have enough algae. The fish deplete their glycogen reserves quickly, and a tank without an established algae crop gives them nothing to eat. Solution: only add otos to a tank that has been running for several months with visible green algae on the glass and decor, drip-acclimate slowly, and supplement immediately with zucchini or algae wafers. Buying a group of six or more also reduces per-fish stress.
Will otocinclus eat my plants or just algae?
Otos target soft green algae — the thin film on glass, broad plant leaves, and smooth hardscape — and generally ignore healthy plant tissue. They are among the safest algae-eaters for a planted tank. They do not touch beard algae or hard green spot algae, so manage your light and nutrients to keep those problem algae types in check.
What you need to keep a otocinclus
The baseline is a heated, filtered 60 L+ tank: a reliable heater to hold 21–26 °C (70–79 °F), a gentle filter that won't batter a otocinclus in the current, and a tight-fitting lid. Cycle the tank fully before adding any fish.
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