Can otocinclus live with siamese algae eaters?

Verdict
Yes

Yes. Otocinclus and siamese algae eaters make a good pair. Both are fine at 75–79°F. Plan on at least 30 gal.

OtocinclusOtocinclus72–79°F · pH 6–7.5 Siamese algae eaterSiamese algae eater75–79°F · pH 6.5–7.5

Why it works

Water side by side

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

Size to scale

Otocinclus · 2 inSiamese algae eater · 6 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

OtocinclusSiamese algae eater
Temperature72–79 °F75–79 °F
pH6–7.56.5–7.5
Adult size2.0 in6.0 in
Minimum tank20 gal30 gal
TemperamentPeacefulPeaceful
Swims atBottomBottom
GroupGroups of 6+Alone or in pairs
DietHerbivoreHerbivore

Better tank mates for otocinclus

All otocinclus tank mates

Better tank mates for siamese algae eaters

All siamese algae eater tank mates

Questions

Can otocinclus live with siamese algae eaters?

Yes. Otocinclus and siamese algae eaters make a good pair. Both are fine at 75–79°F. Plan on at least 30 gal.

What temperature suits both otocinclus and siamese algae eaters?

75–79 °F. Otocinclus need 72–79 °F, siamese algae eaters need 75–79 °F.

What size tank do otocinclus and siamese algae eaters need together?

At least 30 gal, set by the siamese algae eater. Add space for each extra fish.