shark & minnow · freshwater

Rainbow Shark: adult size, tank size & tankmates

The Rainbow Shark (Epalzeorhynchos frenatum) grows to about 7.1 in (15 cm SL). It needs a tank at least 48 inches long and about 64 gallons. It doesn't need a group of its own kind, at 68–79°F.

Try it in the tank builder See tankmates

How big it really gets

Drawn to scale against common tank lengths. Green bars meet the minimum tank length from our sources.

Outgrows most home tanks. Sold as an attractive beginner fish; matures into a territorial bully that terrorizes bottom tankmates in small aquaria.

Will it fit your tank?

Your tank

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Quick facts

Adult size: 7.1 in (15 cm SL)
Minimum tank: 48 inches long and about 64 gallons
Temperature: 68–79°F
pH: 6.5–8
Hardness: 2–15 dGH
Group size: 1 (solitary or pair)
With other fish: semi-aggressive
With its own kind: aggressive
Swims: bottom of the tank
Diet: omnivore
Care level: intermediate
Lifespan: 15 years

Watch for: eats shrimp · jumps, so keep a lid

Rainbow Shark tankmates

Checked with the same rules as our tank builder: temperature overlap, pH and hardness, predation and mouth size, fin-nipping and temperament. Tank size is left out here; check it in the builder.

Good tankmates

Use caution

Avoid

All 105 species we checked against the Rainbow Shark

Species	Verdict	Why
Angelfish	Compatible	No conflicts found
Assassin Snail	Compatible	No conflicts found
Bala Shark	Compatible	No conflicts found
Betta	Compatible	No conflicts found
Black Skirt Tetra	Compatible	No conflicts found
Blood Parrot Cichlid	Compatible	No conflicts found
Bristlenose Pleco	Compatible	No conflicts found
Buenos Aires Tetra	Compatible	No conflicts found
Chinese Algae Eater	Compatible	No conflicts found
Clown Loach	Compatible	No conflicts found
Common / Comet Goldfish	Compatible	No conflicts found
Common Pleco	Compatible	No conflicts found
Convict Cichlid	Compatible	No conflicts found
Denison Barb	Compatible	No conflicts found
Dwarf Gourami	Compatible	No conflicts found
Electric Blue Acara	Compatible	No conflicts found
Electric Yellow Lab	Compatible	No conflicts found
Fancy Goldfish	Compatible	No conflicts found
Firemouth Cichlid	Compatible	No conflicts found
Iridescent Shark	Compatible	No conflicts found
Japanese Trapdoor Snail	Compatible	No conflicts found
Kissing Gourami	Compatible	No conflicts found
Malaysian Trumpet Snail	Compatible	No conflicts found
Moonlight Gourami	Compatible	No conflicts found
Nerite Snail	Compatible	No conflicts found
Oscar	Compatible	No conflicts found
Paradise Fish	Compatible	No conflicts found
Pearl Gourami	Compatible	No conflicts found
Pictus Catfish	Compatible	No conflicts found
Ramshorn Snail	Compatible	No conflicts found
Red-Tail Shark	Compatible	No conflicts found
Scissortail Rasbora	Compatible	No conflicts found
Serpae Tetra	Compatible	No conflicts found
Siamese Algae Eater	Compatible	No conflicts found
Swordtail	Compatible	No conflicts found
Three-spot Gourami	Compatible	No conflicts found
Tiger Barb	Compatible	No conflicts found
Tinfoil Barb	Compatible	No conflicts found
Weather Loach	Compatible	No conflicts found
Yoyo Loach	Compatible	No conflicts found
African Dwarf Frog	Caution	Rainbow Shark grows 5× longer than African Dwarf Frog and may treat it as food.; Rainbow Shark can bully smaller, peaceful African Dwarf Frog.
Black Neon Tetra	Caution	Rainbow Shark grows 4× longer than Black Neon Tetra and may treat it as food.; Rainbow Shark can bully smaller, peaceful Black Neon Tetra.
Bleeding Heart Tetra	Caution	Rainbow Shark can bully smaller, peaceful Bleeding Heart Tetra.
Bolivian Ram	Caution	Rainbow Shark can bully smaller, peaceful Bolivian Ram.
Bronze Cory	Caution	Rainbow Shark can bully smaller, peaceful Bronze Cory.
Bumblebee Goby	Caution	Rainbow Shark grows 4× longer than Bumblebee Goby and may treat it as food.; Rainbow Shark can bully smaller, peaceful Bumblebee Goby.
Cardinal Tetra	Caution	Rainbow Shark grows 4× longer than Cardinal Tetra and may treat it as food.; Rainbow Shark can bully smaller, peaceful Cardinal Tetra.
Celestial Pearl Danio	Caution	Rainbow Shark grows 7× longer than Celestial Pearl Danio and may treat it as food.; Rainbow Shark can bully smaller, peaceful Celestial Pearl Danio.
Cherry Barb	Caution	Rainbow Shark can bully smaller, peaceful Cherry Barb.
Chili Rasbora	Caution	Rainbow Shark grows 8× longer than Chili Rasbora and may treat it as food.; Rainbow Shark can bully smaller, peaceful Chili Rasbora.
Clown Killifish	Caution	Rainbow Shark grows 5× longer than Clown Killifish and may treat it as food.; Rainbow Shark can bully smaller, peaceful Clown Killifish.
Clown Pleco	Caution	Rainbow Shark can bully smaller, peaceful Clown Pleco.
Cockatoo Dwarf Cichlid	Caution	Rainbow Shark can bully smaller, peaceful Cockatoo Dwarf Cichlid.; Rainbow Shark (pH 6.5–8) and Cockatoo Dwarf Cichlid (pH 5–6) prefer different pH.
Congo Tetra	Caution	Rainbow Shark can bully smaller, peaceful Congo Tetra.
Diamond Tetra	Caution	Rainbow Shark can bully smaller, peaceful Diamond Tetra.
Discus	Caution	Rainbow Shark and Discus only share 79–79°F. That's a tight window.
Dwarf Neon Rainbowfish	Caution	Rainbow Shark can bully smaller, peaceful Dwarf Neon Rainbowfish.
Ember Tetra	Caution	Rainbow Shark grows 8× longer than Ember Tetra and may treat it as food.; Rainbow Shark can bully smaller, peaceful Ember Tetra.
Endler's Livebearer	Caution	Rainbow Shark grows 6× longer than Endler's Livebearer and may treat it as food.; Rainbow Shark can bully smaller, peaceful Endler's Livebearer.
Forktail Blue-eye	Caution	Rainbow Shark can bully smaller, peaceful Forktail Blue-eye.
Giant Danio	Caution	Rainbow Shark can bully smaller, peaceful Giant Danio.
Glass Catfish	Caution	Rainbow Shark can bully smaller, peaceful Glass Catfish.
Glowlight Tetra	Caution	Rainbow Shark can bully smaller, peaceful Glowlight Tetra.
Gold Barb	Caution	Rainbow Shark can bully smaller, peaceful Gold Barb.
Guppy	Caution	Rainbow Shark can bully smaller, peaceful Guppy.
Harlequin Rasbora	Caution	Rainbow Shark can bully smaller, peaceful Harlequin Rasbora.
Head-and-tail-light Tetra	Caution	Rainbow Shark can bully smaller, peaceful Head-and-tail-light Tetra.
Hillstream Loach	Caution	Rainbow Shark can bully smaller, peaceful Hillstream Loach.
Honey Gourami	Caution	Rainbow Shark can bully smaller, peaceful Honey Gourami.
Julii Cory	Caution	Rainbow Shark can bully smaller, peaceful Julii Cory.
Kribensis	Caution	Rainbow Shark can bully smaller, peaceful Kribensis.
Kuhli Loach	Caution	Rainbow Shark can bully smaller, peaceful Kuhli Loach.
Lambchop Rasbora	Caution	Rainbow Shark grows 5× longer than Lambchop Rasbora and may treat it as food.; Rainbow Shark can bully smaller, peaceful Lambchop Rasbora.
Lemon Tetra	Caution	Rainbow Shark can bully smaller, peaceful Lemon Tetra.
Marbled Hatchetfish	Caution	Rainbow Shark grows 4× longer than Marbled Hatchetfish and may treat it as food.; Rainbow Shark can bully smaller, peaceful Marbled Hatchetfish.
Molly	Caution	Rainbow Shark can bully smaller, peaceful Molly.
Mystery Snail	Caution	Rainbow Shark (pH 6.5–8) and Mystery Snail (pH unknown) prefer different pH.; Rainbow Shark (2–15 dGH) and Mystery Snail (unknown dGH) prefer different water hardness.
Neon Tetra	Caution	Rainbow Shark grows 5× longer than Neon Tetra and may treat it as food.; Rainbow Shark can bully smaller, peaceful Neon Tetra.
Odessa Barb	Caution	Rainbow Shark can bully smaller, peaceful Odessa Barb.
Otocinclus	Caution	Rainbow Shark grows 4× longer than Otocinclus and may treat it as food.; Rainbow Shark can bully smaller, peaceful Otocinclus.
Panda Cory	Caution	Rainbow Shark can bully smaller, peaceful Panda Cory.
Pea Puffer	Caution	Rainbow Shark grows 5× longer than Pea Puffer and may treat it as food.
Pearl Danio	Caution	Rainbow Shark can bully smaller, peaceful Pearl Danio.
Penguin Tetra	Caution	Rainbow Shark grows 4× longer than Penguin Tetra and may treat it as food.; Rainbow Shark can bully smaller, peaceful Penguin Tetra.
Peppered Cory	Caution	Rainbow Shark can bully smaller, peaceful Peppered Cory.
Platy	Caution	Rainbow Shark can bully smaller, peaceful Platy.
Pristella Tetra	Caution	Rainbow Shark can bully smaller, peaceful Pristella Tetra.
Pygmy Cory	Caution	Rainbow Shark grows 5× longer than Pygmy Cory and may treat it as food.; Rainbow Shark can bully smaller, peaceful Pygmy Cory.
Rosy Barb	Caution	Rainbow Shark can bully smaller, peaceful Rosy Barb.
Rummy-nose Tetra	Caution	Rainbow Shark can bully smaller, peaceful Rummy-nose Tetra.
Silver Hatchetfish	Caution	Rainbow Shark can bully smaller, peaceful Silver Hatchetfish.
Silver Tip Tetra	Caution	Rainbow Shark can bully smaller, peaceful Silver Tip Tetra.
Sparkling Gourami	Caution	Rainbow Shark can bully smaller, peaceful Sparkling Gourami.
Sterbai Cory	Caution	Rainbow Shark can bully smaller, peaceful Sterbai Cory.
Upside-down Catfish	Caution	Rainbow Shark can bully smaller, peaceful Upside-down Catfish.
Variatus Platy	Caution	Rainbow Shark can bully smaller, peaceful Variatus Platy.
White Cloud Mountain Minnow	Caution	Rainbow Shark can bully smaller, peaceful White Cloud Mountain Minnow.
Zebra Danio	Caution	Rainbow Shark can bully smaller, peaceful Zebra Danio.
Amano Shrimp	Avoid	Rainbow Shark will eat Amano Shrimp.
Bamboo Shrimp	Avoid	Rainbow Shark will eat Bamboo Shrimp.
Boesemani Rainbowfish	Avoid	Rainbow Shark (68–79°F) and Boesemani Rainbowfish (81–86°F) need different temperatures.
Cherry Shrimp	Avoid	Rainbow Shark will eat Cherry Shrimp.
Crystal Red Shrimp	Avoid	Rainbow Shark will eat Crystal Red Shrimp.
German Blue Ram	Avoid	Rainbow Shark (68–79°F) and German Blue Ram (81–86°F) need different temperatures.; Rainbow Shark can bully smaller, peaceful German Blue Ram.
Ghost Shrimp	Avoid	Rainbow Shark will eat Ghost Shrimp.

Care notes

Needs: Demands distinct caves and rockwork; requires vegetable and biofilm matter in diet; accomplished jumper requiring tight lid

Group: Strictly solitary; aggressively defends benthic territory against conspecifics and similar bottom dwellers

Temperament: semi-aggressive toward other fish, aggressive toward its own kind. Lives in the bottom of the tank.

Common questions

How big does a Rainbow Shark get?

About 7.1 inches (15 cm SL) as an adult, according to seriouslyfish.com.

What size tank does a Rainbow Shark need?

At least 48 inches long and about 64 gallons. The smallest standard tank that meets that is a 75 gallon.

How many Rainbow Sharks should be kept together?

It can be kept on its own. Strictly solitary; aggressively defends benthic territory against conspecifics and similar bottom dwellers

What fish can live with a Rainbow Shark?

Species that passed every check include Dwarf Gourami, Pearl Gourami, Betta, Angelfish, Bristlenose Pleco, Nerite Snail.

Gear for a Rainbow Shark setup

TankSmallest standard tank that meets its minimum: 75 gallon (48 in long).Find on Amazon →HeaterAbout 2 × 200 W for 75 gallons, holding 68–79°F.Find on Amazon →LidIt jumps. A full lid keeps it in the tank.Find on Amazon →FoodSinking food reaches the bottom before tankmates grab it.Find on Amazon →Test kitCheck ammonia, nitrite and pH. Cycle the tank before adding fish.Find on Amazon →

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Sources

Values come from these pages, in our own words. Status: verified. Last reviewed 2026-10-12.

seriouslyfish.com /species/epalzeorhynchos-frenatum
fishbase.se /summary/Epalzeorhynchos-frenatum.html