Can jack dempseys live with cardinal tetras?

Verdict
No

No. Jack dempseys and cardinal tetras should not share a tank. An adult jack dempsey eats fish that fit in its mouth, and at 2 inches cardinal tetras do.

Jack DempseyJack Dempsey72–86°F · pH 6.5–7.5 Cardinal tetraCardinal tetra76–84°F · pH 4.6–7

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–84°Jack Dempsey 72–86°Cardinal tetra 76–84°
The green band is the temperature range both can live in.
456789Both: 6.5–7Jack Dempsey 6.5–7.5Cardinal tetra 4.6–7
The green band is the pH both tolerate.

Size to scale

Jack Dempsey · 10 inCardinal tetra · 2 in0"2"4"6"8"10"
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

Jack DempseyCardinal tetra
Temperature72–86 °F76–84 °F
pH6.5–7.54.6–7
Adult size10.0 in2.0 in
Minimum tank55 gal20 gal
TemperamentAggressivePeaceful
Swims atMiddleMiddle
GroupAlone or in pairsGroups of 6+
DietCarnivoreOmnivore

Better tank mates for jack dempseys

All jack dempsey tank mates

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Questions

Can jack dempseys live with cardinal tetras?

No. Jack dempseys and cardinal tetras should not share a tank. An adult jack dempsey eats fish that fit in its mouth, and at 2 inches cardinal tetras do.

What temperature suits both jack dempseys and cardinal tetras?

76–84 °F. Jack dempseys need 72–86 °F, cardinal tetras need 76–84 °F.

What size tank do jack dempseys and cardinal tetras need together?

At least 55 gal, set by the jack dempsey. Add space for each extra fish.