Red Tail Shark – Tank Mates, Temperature, Tank Size & Care

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While it’s fun to fill a freshwater aquarium with schooling fish, there’s something to be said for keeping a unique solo bottom dweller like a Red Tail Shark in your tank, too. These semi-aggressive algae eaters can be territorial, but their vibrant markings and active nature makes them a good fit for many communities!

Red Tail Sharks – Overview

Common Name (species)

Red Tail Shark, Red-Tailed Black Shark, Red Tail Sharkminnow
(Epalzeorhynchos bicolor)





Care Level


Average Size

5 to 6 inches in length


Omnivore; consumes algae, plant materials, small insects and crustaceans


Offer commercial omnivore flake or pellet diets supplemented with sinking algae wafers, spirulina pellets, freshly blanched veggies and treats of brine shrimp, bloodworms and Daphnia or shrimp eggs


Mature fish are very active swimmers and explorers; young fish often shy and hide in caves/vegetation during the day


Semi-aggressive and territorial towards other bottom dwellers

Tank Level

Bottom Dweller

Minimum Tank Size

55+ gallons

Temperature Range

72 to 79°F

Water Hardness

5 to 15 dH

pH Range

6.8 to 7.5

Filtration/Flow Rate

Needs well filtered and oxygenated water with a moderate to high current in the lower parts of the tank


Egglayer; rarely breeds naturally in aquariums


Ideal for keeping with upper and mid-level fish like Bala Sharks, Pictus Cats, semi-aggressive and peaceful barbs, Gourami, Angelfish, or with groups of schooling tetras, rasboras or minnows. Avoid keeping with bottom feeders like plecos, loaches, rainbow sharks or other red tailed sharks

OK for Planted Tanks?

Ideal for planted aquariums and prefers habitats with at least some live plants

Introduction to Red-Tailed Black Sharks

If you’re looking for a unique type of fish that will really stand out in the lower parts of your aquarium, consider adding a freshwater shark to your community. One of the most popular and vibrant species is the semi-aggressive Red Tail or Red-Tailed Black Shark (Epalzeorhynchos bicolor). 

Red-tailed black shark nibbling on pebbles.

These sharks aren’t the easiest species to accommodate in a mixed community, but with a moderate amount of planning even an amateur fish keeper can pull it off. Let’s talk about the requirements for keeping a Red Tail in your tank, starting with some background on the species!

Natural History and Conservation

Red Tails are native to Thailand and were introduced to the aquatic trade in the early part of the 20th Century. Originally endemic to rivers and streams throughout the region, this species has become nearly extinct in the wild from over-harvesting and habitat loss, and is currently considered critically endangered:

  • As of 2011, the only known wild Red Tail populations were limited to parts of the Chao Phraya River.
  • Sharks sold in stores and online are captive-bred stock from domesticated lines, and are bred in large-scale operations using artificial hormones to induce spawning.
Chao Phraya River in Thailand
Image Source :

Also known as the Red Tail Sharkminnow, these vibrant fish are members of the carp or Cyprinidae family and are related to minnows, goldfish, and koi. In the wild, Red Tails live along the bottom of swift-moving streams and rivers, where they feed on algae, plant materials, insects, and small crustaceans.

Red Tail Appearance and Mimics

Red tails have a torpedo-shaped body with slightly flat sides and a curved back with a prominent shark-like dorsal fin and forked caudal fin (tail). They have dark red eyes, a slightly angled mouth with two sets of barbels or whiskers, and smaller pectoral, abdominal and anal fins. But their stand-out feature is their markings!

Red Tail Sharks are named for their vibrant red caudal fins. While their bodies are a deep, rich black, that ends in a line right at the caudal peduncle where the red tail starts. Unlike the similar and more friendly Rainbow Shark, Red Tails only exhibit red from the peduncle to the tip of the tail and never on their other fins.

Shark Size and Lifespan

Red-tailed black shark (Epalzeorhynchos bicolor)

Red tails average between 5 and 6 inches from snout-to-tail when mature. Juveniles are sold at around 3 inches in length and reach their adult size in about a year. Red tails typically live for 4 to 6 years in captivity with proper care.

Red Tail Behavior, Temperament and Compatibility 

Red tails have a reputation for being hard to deal with, but they’re actually not that challenging once you understand their needs. While young fish may be shy at first and spend their time hiding in rock caves and vegetation, mature Red Tails are active, semi-aggressive and territorial bottom dwellers.

While Red Tails prefer to dominate the lower parts of your aquarium, they usually leave the middle and upper levels alone. They’ll still chase other fish away from their territory if they happen to swim through, but they won’t attack or hunt your mid-level or surface schoolers: 

  • As long as they have plenty of room along the bottom and no competition, these small sharks usually ignore fish in the other parts of your tank.
  • You can easily keep a Red Tail in a 55-gallon or larger set-up if they’re the only bottom feeder.
  • Red Tails don’t do well together unless kept in groups of 5 or more in very large aquariums or ponds (300-gallon minimum for 5 sharks) with decor dividing the bottom into distinct territories, so they’re not an ideal option for a single-species set-up.

How to Care for Your Red Tail Shark

What’s the best set-up for a Red Tail tank, and what kind of care do they need to thrive? While they are moderately difficult to accommodate initially, they’re not hard to maintain once you’ve established your aquarium!

Tank Set-up and Habitat Requirements

If you want to keep a Red Tail with the least amount of stress, start with an ideal shark set-up and build your community around their needs. Three key features to a great Red Tail tank are: high-quality filtration with a moderate water current and lots of room at the bottom to swim and explore!

Aquarium Size 

Beautiful aquarium in the living room.

While you may be able to temporarily keep a young fish in a smaller set-up, an adult Red Tail needs at least a 55-gallon aquarium to explore, and 75-gallons is even better since they only use the lower part. I don’t recommend keeping multiple Red Tails in the same aquarium unless you’re an experienced shark keeper.


These sharks are not terribly fussy about their substrate, so you can use any type of aquatic soil, sand or gravel you prefer. To recreate their natural habitat, go with a mix of naturally colored gravel and smooth, round pebbles. You can even use a neon-colored kid-friendly product if you’d like!

Temperature and Water Parameters

Red tail sharks prefer warm water from 72 to 79°F, so use a heater to keep your tank’s temperature stable. They’re not sensitive to mineralization and tolerate from 5 to 15 degrees of hardness (dH), and prefer slightly alkaline water with a pH 6.8 to 7.5.

Filtration and Aeration 


Red Tails prefer set-ups that mimic their natural swift-river habitats, so you’ll need a good filtration system to provide a moderate current along the lower parts of your tank. As bottom dwellers, sharks are sensitive to toxins like ammonia and need very clean, well-oxygenated water:

  • A canister system is the ideal filtration option, but you could use a couple of HOBs instead.
  • An internal aquarium powerhead can also provide a moderate to high current across the bottom of your tank if your filter isn’t up to the task, but you don’t need to splash out on an expensive wavemaker.
  • Using an air stone or bubbling device is also recommended to maintain high oxygen levels and provide additional currents in your aquarium.

Lights, Plants and Decorations

I’d definitely get some lights for a shark tank. Red Tails are active during the day, so LED aquarium lights are an inexpensive way to highlight your shark community and will meet the needs of most aquatic plants, too. 

Amazon Natural Aquascape
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Sharks need plenty of open areas for swimming, but they also like to hide and nibble on vegetation. They love to sleep in crevices of rocks and explore interesting sticks and branches. You can use live plants, piles of rocks and driftwood to break up the bottom of your tank and define the edges of your shark’s territory.


If you have a robust filtration system and change the water and the filter media on schedule, then you won’t really have to worry about the effort it’ll take to keep a healthy shark tank. Regular water changes should keep the waste products and toxins under control. Truthfully, your live plants will likely take more work to maintain than your fish.

Feeding Sharks 

Like their cousins, the goldfish, Red Tails are omnivores and eat both plants and live animals. They’ll also scavenge for algae and eat any food scraps on the bottom of the tank missed by your other fish. It’s best to feed your sharks once a day, although I like to fast mine one day a week as well. 

Food for aquarium fish. Photos isolated on white background

What kind of food do Red Tail Sharks prefer? It’s easiest to use a commercial omnivore flake or sinking pellet diet as their primary food, and then supplement with a variety of treats to balance their nutrition:

  • Offer snacks of algae wafers, spirulina pellets and freshly blanched veggies like zucchini, cucumber or peas in place of their usual diet a couple of times a week.
  • Once or twice a week, you can feed your sharks a protein-rich treat of live/frozen/dried brine shrimp, bloodworms, Daphnia or shrimp eggs.

Tank Mates

While I don’t recommend that novices try keeping multiple Red Tails in the same set-up, that doesn’t mean you can’t have any tank mates in a shark tank! If you’re careful in your choice, it’s not hard to find mid-level species that work with these territorial bottom dwellers and have similar water preferences.

Some possible options (depending on your tank capacity and set-up) include:

Neon tetra fish with aquatic plant in aquarium
  • Active mid-level catfish like Bala Sharks or Pictus Cats
  • Angelfish or gourami 
  • Schools of tetras like Neons, Head and Tail Lights, or Emperors
  • Live-bearers such as Mollies or Platies 
  • Semi-aggressive or peaceful barbs
  • Danios, minnows or rasboras

Avoid keeping Red Tails with other bottom dwellers or territorial fish such as loaches, Corydoras species, most types of plecostomus and the majority of freshwater sharks. If your shark starts bullying your community, try breaking up their line of sight with decor.


Red Tails are egg-layers who spawn in rock crevices and driftwood caves in the wild, but it’s very difficult to breed them in captivity

  • Since sharks don’t get along, it’s nearly impossible to keep a mixed-gender group from fighting in an aquarium.
  • Most commercial breeders have large outdoor ponds and use artificial hormones for breeding, so it’s unlikely you’ll see fry even if you create a single-species aquarium.

Health Concerns

Acid acidic water test with ph reagent

Sharks are healthy fish overall, but they’re susceptible to the usual water-borne pathogens, so you should always quarantine new fish and plants for a few weeks before adding them to your community. 

  • A stressed Red Tail appears faded and looks charcoal grey with a pinkish tail. If you see these signs, test your water’s ammonia, nitrate and nitrite levels, do a water change and try to identify the problem. It’s normal for fish to look faded during transport and acclimation.
  • The most common health problems I’ve seen in Red Tails are White Spot Disease (aka Ich) and Fin Rot, and these are both preventable with good aquarium hygiene and the isolation of new or sick community members.

Ideal Red Tail Shark Set-Up: Product and Equipment List

Need some help designing the ultimate beginner’s shark tank? Here’s a detailed list of the equipment and supplies required for a basic planted aquarium to showcase your Red Tail and a small community of fish:

Britain's Biggest Domestic Fish Tank
Image Source:
  • 75-gallon or larger aquarium with stand
  • Hood with cover/lid and LED Light Fixture, or go modern with a glass cover and suspended LED Lights
  • Canister and/or HOB filtration systems
  • Aquarium heater
  • Internal powerhead to push water horizontally across the bottom of the tank
  • Airstone or bubbler with air pump and plastic tubing
  • Fine aquatic soil covered with a mix of gravel and small pebbles, or simply use a commercial gravel-textured plant substrate
  • Variety of short and tall live plants like Hornwort, Java Fern, Anubius, Hygro, Amazon Sword and/or Guppy Grass
  • Decor including piles of rocks, driftwood, sticks and branches

To feed your Red Tails, you’ll need:

  • Commercial omnivore flakes or pellets
  • Sinking algae wafers, spirulina pellets, and/or freshly blanched veggies
  • Treats such as live/dried/frozen brine shrimp, bloodworms, insect larvae, shrimp or Daphnia eggs

To support your planted shark community, you’ll need:

Vilnius, Lithuania A man vacuums a fish tank.
  • Vacuum and hose system, with a bucket for water changes and filter maintenance 
  • Replacement filter media/air stones
  • Water conditioner
  • Liquid aquatic plant food or nutritional tabs
  • Fish net
  • Covered quarantine or hospital tank with sponge filter, air stone and air pump


Have you ever had a Red Tailed Black Shark and did you enjoy our tips for keeping them? Leave a comment below or join the bigger community on social media. We don’t chum the water with novice fish keepers, either, so don’t let a lack of shark experience hold you back!

Jen has more than 30 years experience as a biologist, aquarist, and fishkeeper. She is an expert in setting up new tanks and maintaining naturally-planted freshwater habitats, and has experience raising a wide variety of aquatic species.

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