Red-tailed black shark tank mates

Red-tailed black shark: aggressive, 4.9 in, fine on its own, swims in the bottom and middle of the tank and needs about 76 gallons. The list below checks every species in our catalog against it.

Each species is checked against red-tailed black sharks both ways: mouth size, fin nipping, temperament, territory, water overlap and keeper reports.

Good tank mates

Betta
Betta splendens
Fits
The Siamese fighting fish: one male per tank, warm still water, and no long-finned or nippy tank mates.
2.8 in · 11+ gal · 72–86°F · pH 6–7.5
Angelfish
Pterophyllum scalare
Fits
Tall, graceful cichlids for tall tanks of 30 gallons and up; adults eat neon tetras and shrimp, so stock around them.
3.5 in · 32+ gal · 77–84°F · pH 6–7
Blood parrot cichlid
hybrid
Fits
A man-made hybrid cichlid with a round body and a beak-like mouth that barely closes; usually gentle and rarely able to swallow tank mates.
7.9 in · 36+ gal · 72–82°F · pH 6.5–8
Common pleco
Pterygoplichthys pardalis
Fits
The classic store 'algae eater' that grows to nearly two feet, fouls the water and eats less algae with age; a fish for very large tanks only.
22.8 in · 203+ gal · 77–82°F · pH 7–7.5
Dwarf gourami
Trichogaster lalius
Fits
A bright little gourami popular with beginners; one male per tank, no bettas, and buy carefully, as imported fish often carry an incurable iridovirus.
3 in · 18+ gal · 72–81°F · pH 6–7.5
Leopard sailfin pleco
Pterygoplichthys gibbiceps
Fits
A tall-finned pleco with a brocade pattern that is sold at 2 inches and grows to about 20, needing a very large tank and heavy filtration.
19.7 in · 187+ gal · 77–86°F · pH 5–7
Severum
Heros severus / Heros efasciatus
Fits
A calm, large South American cichlid often kept with angelfish and catfish; eats soft plants and any fish that fits in its mouth.
7.9 in · 76+ gal · 72–84°F · pH 5.5–6.5
Three spot gourami
Trichopodus trichopterus
Fits
The most common gourami: hardy, omnivorous and an air breather, though males can turn quarrelsome, especially when spawning.
5.9 in · 26+ gal · 75–86°F · pH 6–8
Assassin snail
Anentome helena
Fits
A yellow-and-brown striped predatory snail kept to control bladder, ramshorn and trumpet snails; it breeds slowly and never becomes a pest.
1 in · 3+ gal · 70–81°F · pH 7.2–8
Red swamp crayfish
Procambarus clarkii
Fits
A hardy but aggressive American crayfish that digs burrows, wrecks plants and eats snails and fish; invasive in many countries and banned in the EU.
3.9 in · 25+ gal · 68–79°F · pH 7–8.5
Redclaw crayfish
Cherax quadricarinatus
Fits
A large blue-green crayfish with red patches on the claws, up to 8 inches; a predator and plant shredder best kept alone under a tight lid.
7.9 in · 47+ gal · 64–82°F · pH 7.2–8.2
Elephantnose fish
Gnathonemus petersii
Fits
An African fish that finds food with a weak electric field and a long trunk-like chin; nocturnal, very sensitive and in need of sand.
8.9 in · 76+ gal · 73–82°F · pH 6–7.5
Figure eight puffer
Dichotomyctere ocellatus
Fits
A small puffer with a figure-eight pattern for fresh or slightly brackish water; it loves snails and nips slow tank mates.
3.1 in · 22+ gal · 72–79°F · pH 6.5–7.5
Kissing gourami
Helostoma temminckii
Fits
The famous kissing fish grows to about 10 inches and can live over 20 years; its kisses are really contests for dominance.
9.8 in · 95+ gal · 72–86°F · pH 6–8
Paradise fish
Macropodus opercularis
Fits
One of Europe's first aquarium fish: a hardy, striped labyrinth fish that lives without a heater, but males are pugnacious.
3.1 in · 23+ gal · 61–72°F · pH 6–8
Silver mono
Monodactylus argenteus
Fits
A silver, diamond-shaped schooling fish from mangroves that moves towards marine water as it grows; it needs a school and a large brackish tank.
6.7 in · 47+ gal · 75–82°F · pH 7.5–8.5

Risky

And 95 more in the species catalog.

Avoid

And 14 more in the species catalog.

Every tank is different. Set yours up once (size, water, who already lives there) and each species is checked against it.

Related guides