Can red tail sharks live with fancy goldfish?

Verdict
No

No. Red tail sharks and fancy goldfish should not share a tank. Fancy goldfish are coldwater animals (65–74°F); red tail sharks need 72–79°F. They overlap only at 72–74°F, the edge of both ranges.

Red tail sharkRed tail shark72–79°F · pH 6.5–7.5 Fancy goldfishFancy goldfish65–74°F · pH 7–8

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–74°Red tail shark 72–79°Fancy goldfish 65–74°
The green band is the temperature range both can live in.
456789Both: 7–7.5Red tail shark 6.5–7.5Fancy goldfish 7–8
The green band is the pH both tolerate.

Size to scale

Red tail shark · 5 inFancy goldfish · 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

Red tail sharkFancy goldfish
Temperature72–79 °F65–74 °F
pH6.5–7.57–8
Adult size5.0 in6.0 in
Minimum tank55 gal30 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomAll levels
GroupOne per tankAlone or in pairs
DietOmnivoreOmnivore

Better tank mates for red tail sharks

All red tail shark tank mates

Better tank mates for fancy goldfish

All fancy goldfish tank mates

Questions

Can red tail sharks live with fancy goldfish?

No. Red tail sharks and fancy goldfish should not share a tank. Fancy goldfish are coldwater animals (65–74°F); red tail sharks need 72–79°F. They overlap only at 72–74°F, the edge of both ranges.

What temperature suits both red tail sharks and fancy goldfish?

72–74 °F. Red tail sharks need 72–79 °F, fancy goldfish need 65–74 °F.

What size tank do red tail sharks and fancy goldfish need together?

At least 55 gal, set by the red tail shark. Add space for each extra fish.