Can fancy goldfish live with cardinal tetras?

Verdict

No. Fancy goldfish and cardinal tetras should not share a tank. Fancy goldfish are coldwater animals (65–74°F); cardinal tetras need 76–84°F. No temperature suits both.

Fancy goldfish65–74°F · pH 7–8

Cardinal tetra76–84°F · pH 4.6–7

What to watch

Deal breakerFancy goldfish are coldwater animals (65–74°F); cardinal tetras need 76–84°F. No temperature suits both.
Watch outWater chemistry is a squeeze. The only pH that suits both is around 7.

Water side by side

The ranges do not meet, so one of them would always be too warm or too cold.

The green band is the pH both tolerate.

Size to scale

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

	Fancy goldfish	Cardinal tetra
Temperature	65–74 °F	76–84 °F
pH	7–8	4.6–7
Adult size	6.0 in	2.0 in
Minimum tank	30 gal	20 gal
Temperament	Peaceful	Peaceful
Swims at	All levels	Middle
Group	Alone or in pairs	Groups of 6+
Diet	Omnivore	Omnivore

Better tank mates for fancy goldfish

All fancy goldfish tank mates

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Questions

Can fancy goldfish live with cardinal tetras?

No. Fancy goldfish and cardinal tetras should not share a tank. Fancy goldfish are coldwater animals (65–74°F); cardinal tetras need 76–84°F. No temperature suits both.

What temperature suits both fancy goldfish and cardinal tetras?

None. Fancy goldfish need 65–74 °F and cardinal tetras need 76–84 °F, so the ranges do not meet.

What size tank do fancy goldfish and cardinal tetras need together?

At least 30 gal, set by the fancy goldfish. Add space for each extra fish.