Can harlequin rasboras live with arowanas?

Verdict

No. Harlequin rasboras and arowanas should not share a tank. An adult silver arowana eats fish that fit in its mouth, and at 2 inches harlequin rasboras do.

Harlequin rasbora72–80°F · pH 6–7.5

Silver arowana75–86°F · pH 6–7

What to watch

Deal breakerAn adult silver arowana eats fish that fit in its mouth, and at 2 inches harlequin rasboras do.
Deal breakerArowanas are aggressive and will bully peaceful harlequin rasboras.
Watch outArowanas grow to 36 inches and need 250 gallons, far more than a tank set up for harlequin rasboras.

What works

Both are fine at 75–80°F.
pH 6–7 suits both.
They use different parts of the tank: harlequin rasboras the mid, arowanas the top.

Water side by side

The green band is the temperature range both can live in.

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

	Harlequin rasbora	Silver arowana
Temperature	72–80 °F	75–86 °F
pH	6–7.5	6–7
Adult size	2.0 in	36.0 in
Minimum tank	10 gal	250 gal
Temperament	Peaceful	Aggressive
Swims at	Middle	Top
Group	Groups of 6+	One per tank
Diet	Omnivore	Carnivore

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can harlequin rasboras live with arowanas?

No. Harlequin rasboras and arowanas should not share a tank. An adult silver arowana eats fish that fit in its mouth, and at 2 inches harlequin rasboras do.

What temperature suits both harlequin rasboras and arowanas?

75–80 °F. Harlequin rasboras need 72–80 °F, arowanas need 75–86 °F.

What size tank do harlequin rasboras and arowanas need together?

At least 250 gal, set by the silver arowana. Add space for each extra fish.