Can red tail sharks live with hatchetfish?

Verdict
Yes

Yes. Red tail sharks and hatchetfish get along in the same tank. Both are fine at 75–79°F. Plan on at least 55 gal.

Red tail sharkRed tail shark72–79°F · pH 6.5–7.5 HatchetfishHatchetfish75–81°F · pH 5.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–79°Red tail shark 72–79°Hatchetfish 75–81°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Red tail shark 6.5–7.5Hatchetfish 5.5–7.5
The green band is the pH both tolerate.

Size to scale

Red tail shark · 5 inHatchetfish · 1.5 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 sharkHatchetfish
Temperature72–79 °F75–81 °F
pH6.5–7.55.5–7.5
Adult size5.0 in1.5 in
Minimum tank55 gal20 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomTop
GroupOne per tankGroups of 6+
DietOmnivoreCarnivore

Better tank mates for red tail sharks

All red tail shark tank mates

Better tank mates for hatchetfish

All hatchetfish tank mates

Questions

Can red tail sharks live with hatchetfish?

Yes. Red tail sharks and hatchetfish get along in the same tank. Both are fine at 75–79°F. Plan on at least 55 gal.

What temperature suits both red tail sharks and hatchetfish?

75–79 °F. Red tail sharks need 72–79 °F, hatchetfish need 75–81 °F.

What size tank do red tail sharks and hatchetfish need together?

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