Can bettas live with otocinclus?

Verdict
Yes

Yes, bettas and otocinclus can live together. Both are fine at 76–79°F. Plan on at least 20 gal.

BettaBetta76–82°F · pH 6.5–7.5 OtocinclusOtocinclus72–79°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–79°Betta 76–82°Otocinclus 72–79°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Betta 6.5–7.5Otocinclus 6–7.5
The green band is the pH both tolerate.

Size to scale

Betta · 2.5 inOtocinclus · 2 in0"1"2"3"4"5"6"
Adult length in an aquarium. A fish can swallow anything that fits in its mouth, roughly a third to half its own length for predators.

Care at a glance

BettaOtocinclus
Temperature76–82 °F72–79 °F
pH6.5–7.56–7.5
Adult size2.5 in2.0 in
Minimum tank5 gal20 gal
TemperamentSemi-aggressivePeaceful
Swims atTopBottom
GroupOne per tankGroups of 6+
DietCarnivoreHerbivore

Better tank mates for bettas

All betta tank mates

Better tank mates for otocinclus

All otocinclus tank mates

Questions

Can bettas live with otocinclus?

Yes, bettas and otocinclus can live together. Both are fine at 76–79°F. Plan on at least 20 gal.

What temperature suits both bettas and otocinclus?

76–79 °F. Bettas need 76–82 °F, otocinclus need 72–79 °F.

What size tank do bettas and otocinclus need together?

At least 20 gal, set by the otocinclus. Add space for each extra fish.