How to Care for Red Tail Sharks: A Complete Fact Sheet, Breeding, Behavior, and Care Guide

Red Tail Sharks are some of nature’s most striking wonders.

Even though they do not get along well with other members of their own species, their beauty and intelligence make them a favorite among home aquarists. 

Quick Intro to Red Tail Sharks

Family Name	Cyprinidae
Scientific Name	Epalzeorhynchos bicolor or Epalzeorhynchus bicolor
Other Names	Redtail Sharkminnnow, Red Tailed Labeo, Red-tailed Black Shark
Care Level	Moderate
Region of Origin	Thailand, possibly originating in the Mekong Basin
Distant Relatives	Barbs and danios

General Appearance

Slim and sleek jet black fish with a bright red tail. These beautiful fish appear shark-like even though they are no relation to saltwater species.

Males vs. Females

Females are a bit larger and more rounded in the stomach region. Both have the same striking black body and fire tail coloring.

How They Move in the Tank

Fins and body shape are made for cutting quickly and powerfully through the water and the stamina to chase other fish from their territory as long as it takes. Every aspect of this fish says power and mystery.

Habitat Type

Bottom level of freshwater floodplains and rivers. As of 2011, Red Tail Sharks are listed as critically endangered in their natural habitat. Most, if not all fish available for home aquariums are captive bred.

Optimal Water Conditions For Red Tail Sharks

You can start off with a neutral pH for Red Tail Sharks and then adjust towards slightly acidic or slightly alkaline if you see rapid gill pumping, listlessness (at night), or other signs that the water chemistry is wrong. 

Water Temperature	71.6 – 78.8 degrees fahrenheit
Water Flow Rate	Rapid, as with other river fish
pH	6.5 – 7.5
Water Hardness	10 – 15 dh
Aquarium Salt (Y/N)	No
Tannins (Y/N)	You can give this a try if the fish seems stressed and there is no way to reduce the light in the tank further. Just be careful not to let the tank pH go below 6.5.

Tank Setup

Minimum Tank Size	50 gallon tank
Optimal Tank Size	Over 50 gallon large tank
Optimal Tank Shape	Low and long
Best Filter Type	Power filter with secondary bubble up filters for zeolites, and nitrate/nitrite absorbing pads.
Extra Air and How to Provide It	Use airstones or air curtains at the substrate level
Testing Schedule First Year	Test for ammonia and nitrites if you see signs of fish stress. Check pH, hardness, and nitrates weekly
Testing Schedule After 1 Year	Check pH, hardness, and nitrates biweekly.

Creating the Landscape 

Even though Red Tail Sharks are very aggressive, they also tend to be insecure. 

A well-designed landscape with a lot of variety to meet their changeable moods is very important to prevent immune system collapse and illness.

Rocky substrate or gravel	Patches
Sandy substrate	In terraces
Overhangs and caves	Yes
Open water	Some areas, but not whole tank.
Densely planted	Patches around the tank.
Best Plants	Since red tail sharks don’t snack on plants, you can put both fast-growing and slow-growing low light tolerant plants in the tank.
Best Lighting	Medium to low light. Red Tail Sharks are nocturnal, so if you want to observe them during day hours, it is best to keep the tank on the darker side, or use plenty of plants that provide dense shade to the substrate region.
Best Decorations	Driftwood and rocks
Decorations to Avoid	Surfaces inside the tank that generate mirror effects, plastic toys they can scratch or injure themselves on.

Physiological Considerations

Maximum Size	4.5 inches
Rate of Growth	Tails will turn red about 10 weeks after the eggs hatch
Life Span	5 – 8 years
Temperament	Aggressive and territorial. Only keep one Red Tail Shark to a tank.
Preferred Tank Region	Bottom
Scale Thickness	Normal thickness, so you can use most antibiotics safely.
Gill Considerations	As fast water fish, you may notice increased rates of gill flukes or other gill diseases if the water flow is too slow.
Swimbladder Considerations	Since these are swim bodied fish that usually dwell on the bottom of the tank, they should not show much in the way of swim bladder problems. If you notice difficulty reaching the top of the tank, lower the water level.
Fin Shape Considerations	Sleek, powerful fins that make them fast swimmers and capable of jumping. Never keep these fish in a tank without a lid or they will jump out.

Society

Red Tail Sharks are one of the few home aquarium fish where having any kind of society is virtually impossible. They are very aggressive and territorial fish that do not even get along long enough to mate under these conditions. 

• Male to Female Ratio – Only keep one of this species to a tank as they will be aggressive to each other regardless of gender and reproductive readiness.
• Schooling Behaviors – Red Tailed Sharks are extremely solitary and will not school with other fish.
• Suitable Tankmates – Other aggressive fish that are around the same size. Some recommend angel fish, however, their fins simply cannot take being nipped or damaged during a fight. Choose more sturdy fish with compact fins and the capacity to heal well such as Buenos Aires Tetras and Tinfoil Barbs and some Cichlids. You can expect fights to happen in any tank with a Red Tail Shark in it.
• Species to Avoid – Smaller or more peaceful fish such as glass tetras, poor fighters (outside of their species) such as bettas, aggressive but small fish such as tiger barbs, or fighting fish that bash instead of bite (like goldfish).

Common Behaviors You May See in Aggressive Red Tail Sharks

Changes in Eye Color	No
Chasing	Yes, to the point where the other fish will succumb from exhaustion
Circling with Fins Splayed	No
Fins Splayed as Other Fish Approach or When Approaching Other Fish	Possible. Red Tail Sharks like to hide in caves, so they may simply come out quickly and try to rush any fish invading their territory.
Intensified Colors	No, however their tails may become less red in coloring when stressed because of aggression related issues as well as water chemistry issues.
Mouth to Mouth Biting	No
Nipping	No or rarely

Anti-Bullying Solutions That Work Best With Red Tail Sharks

Add More Fish of the Same Species	No
Add More Males or Females	No
Change Feeding Methods, Quantity, or Number of Feedings	May help when combined with other actions. Broadcast food widely so that other fish can eat in different parts of the tank.
Increase Number of Hiding Places	Yes
Isolate the Bully	Yes
Move Decorations to Shake Up Territorial Boundaries	Yes
Move to a Bigger Tank	Yes
Water Chemistry or Temperature Changes	No

Gender, Breeding, and Reproductive Considerations

Even though there are plenty of Red Tail Black Sharks available for home aquarists, they are almost extinct in their native habitat. 

To add insult to injury, they can only be bred on large farms because of the difficulty in getting males and females to put their territorial aggression aside long enough to breed. 

Breeding at home is basically impossible.

Since they have never been successfully bred in a home aquarium, the following information is based on my suggestions for what works in other fish where breeding is complicated.

How to Recognize Breeding Pairs

Unless you have a large enough community tank, it will not be possible to keep males and females together long enough to see if there are recognizable breeding patterns.

I recommend putting a clear partition between two fish that you suspect are opposite genders to see if their behavior towards each other changes over time.

If you see a change (such as the male showing more interest in a cave near the partition, etc) around the time the female becomes heavier in the belly (which means she has eggs ready to release), then you might try opening the partition to see what they do.

How Many Babies?

Unknown

Separate Hatchery?

Unknown

Special Needs for the Fry

Unknown

Managing the Babies

When Red Tail Sharks spawn, they usually do so in caves. You can try putting some aquarium grass in or around the caves to catch some fertilized eggs. 

If you are fortunate enough to see them spawn, divide the tank into 3 sections. In one section, you will take care of the eggs by feeding the fry infusorans and fry food once they hatch. Use the other section to keep the female and some fertilized eggs. Then, use the third section for males and some eggs.

If you notice either of the adults consuming eggs, then you can conclude these fish do not have a role in taking care of offspring after spawning occurs.

The exception to this rule is if you see the parent fish only consuming opaque or white eggs, since this is an indicator the egg is not going to hatch.

Nutritional Needs

Red Tailed Sharks will eat food remains left by other fish, as well as seek out worms and other small creatures. They will also consume algae along the bottom of the tank.

Wild FoodsWorms, other animals that would live at the bottom of a river, some plant matter, and they are algae eaters.
How Obtained	Scavenger and hunter
How to Replicate	Use live or frozen foods if they are available
Best Sustenance Food	If the fish go to the surface to eat, you can use tropical fish pellets or flake food. Otherwise, use sinking fish food forms. When feeding tubifex worm cubes, place the cube near the substrate region.
Additional Foods for Optimal Health	Tubifex worms, live brine shrimp, zucchini
Special Foods for Color and Growth	Bloodworms, peas, cucumbers
When and How Often To Feed based on Place in Life Cycle	2 – 4 times a day. Feed younger fish more often.

Finicky Fish Management Troubleshooting Checklist 

Check (and get rid of) Ammonia and Nitrites	Yes
Lower Nitrates to Levels	No
Test (and Adjust if Needed) Other Water Chemistry Parameters	Yes
Check for Illness	Yes
Look for Signs of Bullying Such as Missing Scales, Nipped Fins or other Damage	Yes, also watch for decreased body color intensity.
Try These Frozen/Thawed or Live Foods	Brine shrimp, blood worms, tubifex worms, peas, cucumber, blanched zucchini.

Observe for Possible Environmental Stresses

Too Much/Too Little Light: Reduce lighting or leave the tank dark for longer intervals.

Sounds: If you notice the fish startles at loud sounds or goes to hide, then this may be causing problems during feeding time. 

Vibrations: Possible.

Odors From Air Sprays, Cooking, Construction, etc: Yes – this can easily be a factor with any fish, including Red Tail Sharks.

Common Diseases and How to Avoid and Treat Them

Since Red Tail Sharks get stressed out easily, they are more susceptible to ich and velvet than some other tropical fish. 

There are no specific diseases, however an immune system collapse with these fish can happen very quickly and cause multiple disease to emerge at once or in rapid succession. 

How to avoid species specific diseases: Keep the water chemistry in optimal levels and avoid sudden changes. Use chemicals to adjust water parameters instead of water changes. 

Do not overstock the tank. These fish are very territorial. Even though they have more than enough stamina to chase other fish to death, constant aggression still takes a toll on them. 

Best antibiotics: You can use any antibiotic suitable for freshwater fish.

Treatments to avoid: I do not recommend antibiotics with salt additives as they can build up in the tank and are hard to remove. If you wind up having to treat for 2, 3, or more infections in rapid succession, you may wind up with too much salt in the tank, or a fish that dies of stress because of all the water changes. 

Food recommendations

Anti-parasite flakes or pellets to cover any internal infections that may occur.

Isolation or Hospital Tank?

Isolation in a separate partition (preferably where the fish has it’s territory). 

3 Interesting Facts About Red Tail Sharks

1. As you become acquainted with Red Tail Black Sharks, their body color will act as a reliable barometer for the overall health of the tank. If you see fading colors, check for water chemistry and tank mate compatibility issues. 
2. Even though red tail sharks are nocturnal, they can become active in the day, or any other time when food is available
3. These fish are usually happiest when they are hiding in their cave and have no other fish visiting their territory.

Red Tail Sharks are fairly hearty fish that will add a beautiful accent to larger aquariums. They can quickly become the favorite in the tank as long as you can manage aggression related issues. 

Where to Buy Red Tail Sharks

While you may be able to find them at a local pet shop, we recommend, trying these from Amazon: