What Are the Fish That Swim With Sharks? (And What If You Mean Aquarium 'Sharks'?)

By Hektor Jorgo Published September 20, 2022 Updated June 13, 2026 5 min read

A freshwater aquarium stocked with several fish commonly given 'shark' common names

Quick Facts

Ocean Fish Associated With Sharks: Remoras, pilot fish, certain jacks, and cleaner wrasse are well-known examples
Why They Associate With Sharks: Protection from predators, access to leftover food, and in cleaner wrasse's case, feeding on parasites
Are Any of These Aquarium Fish?: Not typically — these are open-ocean/reef relationships not usually replicated in home aquariums
Freshwater 'Shark' Fish: Bala shark, red tail shark, rainbow shark, roseline (denison barb) — none are true sharks
Are Freshwater 'Sharks' Related to Real Sharks?: No — the name refers to body/fin shape, not taxonomy
Colombian/Berney's 'Shark Catfish': Also not true sharks — Ariidae catfish named for a similar shape resemblance
Common Theme: 'Shark' is one of the most overused descriptive common names in the aquarium trade

"What fish swim with sharks?" is a question with two very different answers depending on what you're actually trying to find out — and given how often "shark" shows up as a common name for freshwater aquarium fish that have nothing to do with actual sharks, it's worth addressing both.

Short Answer

In the ocean, fish like remoras, pilot fish, certain jacks, and cleaner wrasse are known for swimming closely with sharks, generally for protection, feeding opportunities, or (in cleaner wrasse's case) parasite removal — none of which is something a home aquarium replicates. If you're actually researching freshwater aquarium fish and arrived here via "shark" in a fish's name, you're almost certainly thinking of fish like the Bala shark, red tail shark, rainbow shark, or "shark catfish" species like Colombian shark catfish and Berney's shark catfish — none of which are actual sharks. The "shark" name in freshwater fishkeeping is almost always about body shape, not biology.

Real Sharks: Fish That Actually Swim Alongside Sharks in the Ocean

A handful of species have genuine, documented associations with sharks in the wild:

Remoras attach to sharks (and other large marine animals) using a modified sucker-like dorsal fin, riding along and feeding on scraps, parasites, and occasionally dead skin
Pilot fish swim near sharks — historically, sailors believed pilot fish "guided" sharks (hence the name), though the more likely explanation is a mix of protection from other predators and opportunistic feeding
Jacks and other fast open-water fish are frequently seen near sharks in photos and footage, likely for similar protective/opportunistic reasons
Cleaner wrasse, in reef environments, interact with a range of larger fish (including, at times, sharks) to remove parasites and dead tissue

These are wild ecological relationships in open ocean and reef environments — not something replicated in aquariums, and not species typically kept in home tanks at all (remoras and pilot fish in particular are large, pelagic, and not aquarium fish in any practical sense).

If You're Asking About Aquarium "Sharks"

Given that this is a freshwater aquarium site, it's a safe bet that most people landing on this question are actually trying to figure out something about a freshwater fish with "shark" in its name — and there are more of these than you might expect, none of which are remotely related to actual sharks.

The "shark" naming convention in freshwater fishkeeping comes down to body and fin shape: a streamlined body, a forked tail, and sometimes a tall dorsal fin are enough to earn the name, the same way other descriptive trade names get applied based on appearance rather than taxonomy — see also our discussions of "stingray" plecos and "banjo" catfish for similar examples of shape-based naming.

Freshwater Fish Commonly Called "Sharks"

A few of the more commonly encountered examples:

Bala shark (Balantiocheilos melanopterus) — a large, schooling cyprinid (related to barbs and carp) with a sleek, fork-tailed shape. We've covered this species in detail, including why its size and water chemistry needs make it a poor match for African cichlid tanks despite both being popular "large showpiece fish."
Red tail shark and rainbow shark (genus Epalzeorhynchos) — smaller, more territorial cyprinids named for fin coloration and shape rather than overall size.
Roseline shark / Denison barb — another cyprinid sometimes marketed with "shark" in the name, again based on body shape.
"Shark catfish" — a separate naming pattern entirely, applied to certain Ariidae catfish like Colombian shark catfish and Berney's shark catfish, named for a passing resemblance to small sharks in body and fin profile.

What unites all of these is the name, not the biology — a Bala shark and a Colombian shark catfish aren't related to each other any more than either is related to an actual shark.

Choosing Tank Mates for Freshwater "Shark" Fish

This is the practical trap worth avoiding: don't assume two fish are compatible just because they share "shark" in the name. As covered in their respective guides:

Bala sharks need a very large tank (125+ gallons) and their own school, and their water chemistry preferences don't align well with hard-water African cichlid setups
Colombian shark catfish and Berney's shark catfish share a family and some care overlap with each other, but neither shares much in common, practically speaking, with a small territorial red tail shark beyond the name
Tank size, water chemistry, temperament, and social structure (schooling vs. solitary vs. territorial) all vary widely among fish that happen to share "shark" as part of their common name

If you're planning a stocking list and a fish's name includes "shark," treat that as a cue to look up the actual species — the name tells you almost nothing reliable about size, temperament, or compatibility on its own.

Quick Reference

In the ocean: remoras, pilot fish, jacks, and cleaner wrasse are known to swim with sharks — not aquarium fish
In freshwater aquariums: "shark" is a body-shape-based common name, not a taxonomic group
Bala shark, red tail shark, rainbow shark, and "shark catfish" (Colombian, Berney's) are all unrelated to each other and to real sharks
Don't assume compatibility between "shark"-named fish based on the name alone
Research the actual species (tank size, water chemistry, temperament) before stocking
This naming pattern is common in the trade — see also "stingray" plecos and "banjo" catfish for similar examples

Frequently Asked Questions

What fish actually swim with sharks in the ocean?

Several species are known for associating closely with sharks in the wild. Remoras attach to sharks (and other large animals) using a specialized sucker-like fin and feed on scraps and parasites. Pilot fish swim alongside sharks, historically thought to 'guide' them (hence the name), likely benefiting from protection and feeding opportunities. Certain jacks and other fast-swimming open-water fish are also commonly photographed near sharks, often for similar reasons — proximity to a large predator can mean protection from other predators and access to food. Cleaner wrasse, in reef settings, may interact with sharks (among other fish) to feed on parasites and dead tissue. None of these relationships are something a home aquarium replicates — they're open-ocean and reef ecological relationships, not aquarium stocking suggestions.

If I'm stocking a freshwater tank, what does 'shark' usually mean?

In freshwater aquarium contexts, 'shark' is almost always a common name based on body or fin shape, not any taxonomic relationship to actual sharks. The Bala shark (Balantiocheilos melanopterus) is actually a large cyprinid (related to barbs and carp), named for its sleek, fork-tailed, shark-like silhouette. Red tail sharks and rainbow sharks (genus Epalzeorhynchos) are similarly named for body shape and fin profile. None of these fish are sharks in any biological sense — and this naming pattern extends to catfish too, as discussed in our guides to Colombian shark catfish and Berney's shark catfish, both of which are Ariidae catfish named for a passing resemblance to small sharks.

Are freshwater 'shark' fish good tank mates for each other?

Not necessarily — sharing a common-name pattern doesn't mean these fish share care requirements, temperament, or even water chemistry preferences. The Bala shark, for example, needs a very large tank (125+ gallons) and a school of its own kind, and our African cichlid coverage discusses why pairing it with hard-water cichlids is often a mismatch despite both being large, active fish. Similarly, Colombian shark catfish and Berney's shark catfish share a family (Ariidae) and some care overlap, but a red tail shark (a territorial cyprinid) and a Bala shark (a large schooling cyprinid) have quite different social needs despite both being called 'sharks.' The name is a starting point for research, not a stocking shortcut.

Why are so many freshwater fish named after sharks?

Body shape is the common thread — a sleek body, a forked or pointed caudal fin, and sometimes a dorsal fin profile reminiscent of a shark's are enough for a common name to stick, regardless of the fish's actual family or behavior. This is part of a broader pattern in the aquarium trade where descriptive common names get applied based on appearance across unrelated species — we've covered similar cases with 'stingray' plecos (named for a spot pattern, not a relationship to stingrays) and 'banjo' catfish (named for body outline, with 'Asian banjo catfish' being an entirely different family from true South American banjo catfish). 'Shark' just happens to be one of the more frequently reused names, likely because the silhouette is instantly recognizable.

Sources & Further Reading

About the Author: Hektor Jorgo

Co-Founder & Marine Biologist

Hektor is a co-founder of Sea Life Planet and has kept reef and freshwater aquariums for over 15 years. He holds a background in marine biology and focuses on species care accuracy, water chemistry, and tank husbandry.