Otocinclus

Otocinclus vittatus

Also sold as Ottos · Otos · Oto · Otocinculus · Dwarf suckermouth catfish

Synonyms Oto cat · Oto cats · Dwarf sucker · Otocinclus affinis · Otocinclus catfish · Otto cat

Otocinclus (Otocinclus vittatus) is a peaceful freshwater fish that reaches about 4 cm (1.6 in) and swims along the bottom in a shoal. It wants 70–79°F (21–26°C) and pH 6–7.5, is kept in groups of 6 or more, and needs a tank of at least 40 L (11 gal).

At a glance

Type	Fish
Adult size	4 cm (1.6 in)
Minimum tank	40 L (11 gal)
Group size	6 or more
Temperature	70–79°F (21–26°C)
pH	6–7.5
Temperament	Peaceful
GH	2–16.5
Lifespan	3–5 years
Eats shrimp	No

Before it goes in

Otocinclus needs at least 40 L (11 gal). The smallest size in this library that clears that is the 15 Gallon.
Keep 6 or more. Below that it hides, colours down and is far more likely to be picked on.
It leaves shrimp and small fish alone.
It holds at 70–79°F (21–26°C). That shares a window with Betta and Cherry Shrimp, but not with Discus.
It grazes algae hard, which is most of the reason people buy it.
Sources say not to put it in a newly set-up tank — give the tank a few months first.
A group of 6 takes up roughly 51% of what a 15 Gallon will comfortably hold, so plan the rest of the stock around it.

What tank size does it need?

At least 40 L (11 gal). The smallest size here that clears it is the 15 Gallon.

How many should I keep?

6 or more. Fewer than that and it spends its time hiding instead of out in the open.

Will it eat shrimp?

No — adult shrimp and their young are both safe with it.

What water does it want?

70–79°F (21–26°C), pH 6–7.5, GH 2–16.5.

How long does it live?

3–5 years in a tank that suits it. That is how long you are signing up for.

Can it go in a new tank?

No. Sources say not to add it to a newly set-up tank — it wants a tank that has been running for months.

Good tank mates

Tank mates from this library that share its temperature window, are peaceful and eat neither it nor its young: Cherry Shrimp, Goldfish, Bristlenose Pleco, Celestial Pearl Danio and Molly.
Plants that hold up with it: Hygrophila corymbosa 'Siamensis', Water Sprite, Anubias nana 'Petite' and Cryptocoryne wendtii.

Often compared with

	Otocinclus	Borneo Sucker Loach	Glowlight Tetra
Adult size	4 cm	4 cm	4 cm
Min tank	40 L	54 L	60 L
Group	6+	1+	6+
Temperature	70–79°F (21–26°C)	68–75°F (20–24°C)	72–82°F (22–28°C)
Eats shrimp	No	Shrimplets only	—

More livestock

Plan a tank with Otocinclus →

Sources (7) · checked Sep 2026