Why are rope fish popular in pet stores despite their size?

Juveniles are sold at 4-8 inches and look like harmless oddities. They grow quickly and most owners cannot rehome them when they reach adult size.

Do rope fish need to be kept in groups?

They are solitary hunters in the wild. Keeping one or several has similar outcomes for tankmates, which is that small fish get eaten.

Can rope fish be kept with large fish safely?

Yes. Rope fish will not attack fish too large to swallow. They are not aggressive toward equals, just predatory toward anything small.

Can Betta Fish Live With Rope Fish?

By Alex WalshLast reviewed Apr 18, 2026

No, rope fish are 20-24 inch nocturnal predators with a strong appetite for small fish like bettas.

Why

Rope fish reach 20-24 inches and need a 55-gallon minimum tank as active nocturnal hunters.
They are obligate carnivores with a documented appetite for any fish small enough to swallow.
Rope fish are nocturnal and hunt at night when bettas are sleeping at the surface.
They have flexible bodies that allow them to access crevices and hunt in spaces a betta cannot escape.

Minimum shared tank

55 gallons

Shared temperature range

76-82°F

What could go wrong

The betta vanishes overnight and the rope fish is found bloated the next morning from its meal.

If you keep them in separate tanks

Sized for the 55 gallon minimum this pairing needs. Affiliate links — we earn a small commission if you buy through them.

Fluval 307 Performance Canister Filter

Oversized filtration is what lets you stock two species together without water quality crashing. Rated for a tank slightly larger than the 55 gallon minimum.

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Eheim Jager 300W Thermostat Heater

Holds a steady temperature inside the 76-82°F window both species need.

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API Freshwater Master Test Kit

Keep ammonia, nitrite, and nitrate in check. Two-species tanks have more bioload and less margin for error than single-species setups.

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Better pairings to consider

Bettas do well in species tanks or with peaceful diurnal tankmates. Rope fish need species tanks with other large peaceful fish or cichlids of similar size.