The Ultimate Red Tail Shark And Rainbow Shark Care


The Rainbow Shark and the Red Tail Shark are two favorite fishes in the tropical aquarium hobby. Both these species display lots of personality in the tank.

But they’re not true Sharks. Rainbow Sharks and Red Tail Sharks are part of the family Cyprinidae from which Carps and Minnows hail.

The Difference Between The Rainbow Shark And The Red Tail Shark

Too many people get the Rainbow Shark and the Red Tail Shark mixed up. So before we discuss how to care for these awesome creatures, let’s find out what the difference is between them.

Rainbow Sharks and Red Tail Sharks have the same black body (sometimes lighter for the Rainbow) and torpedo-like shape. They have pointed fins reminiscent of a true shark. But a Rainbow Shark’s fins and tail are red or bright orange while the Red Tail Shark’s fins are black. The only red part of the Red Tail Shark, as the name suggests, is its tail.

Other than that, both species display the same dominant behavior. Some report that the Red Tail Shark is more aggressive, but that depends on aquarium conditions. If there are no bigger fish in the tank than a Shark, it will become the ‘tank boss’.

Origins Of The Rainbow Shark And The Red Tail Shark

The Rainbow Shark is a Southeast Asian freshwater carp. The Red Tail Shark, in particular, is endemic to Thailand.

These species carry the name “Shark” because of their long nose, pointed fins, and torpedo body.

An alternative variety, the Albino Rainbow Shark, possesses the same body shape but with white color. It retains the color of the fins: red or bright orange.

The Rainbow Shark is one of currently 5 species with a GloFish counterpart. The GloFish Rainbow Shark can either be neon purple, orange, blue, or green. These are genetically modified and are not found in the wild.

Both the Red Tail Shark and the Rainbow Shark are endangered in the wild. Conservationists surmise that there are more of them in aquariums than there are in the streams and rivers of their origin. By that, you can say that the hobby saved the species.

Red Tail Shark And Rainbow Shark Behavior

They look fierce, and they behave the same.

Rainbow Sharks and Red Tail Sharks are classified as semi-aggressive. They are indifferent to other fish during their juvenile stage but become moody, territorial loners at maturity. They rarely nip or bump other fish but they do love to chase those that come near its territory.

But this attitude is no reason for them to be attacking other fish if tank conditions are right and you have compatible tank mates. We discuss this at length in our article “Is It Normal For Red Tail Sharks To Attack Each Other?”.

If aggression is a constant issue, it may be because of several correctible factors. One of them is your aquarium setup in general. We have input on tank size for Rainbow Shark or Red Tail Sharks which we will discuss later.

Red Tail Shark -ExploreFishWorld
Red Tail Shark -ExploreFishWorld

Some Sharks are nocturnal. You may even not see them during the day as some prefer to be active at night. Or you may not see them at all for lengthy periods.

Rainbow Shark ExploreFishWorld
Rainbow Shark ExploreFishWorld

If kept in large groups even through adulthood, Sharks will keep a hierarchy. It would be easier to get them together as a group (either juveniles or older) so they can establish this early. If you add Sharks one or two at a time to an already established community, expect scuffles until an alpha emerges.

Rainbow Shark And Red Tail Shark Water Parameters And Facts

These are the parameters that Rainbow Sharks and Red Tail Sharks usually prefer.

Temperature77 – 78°F (25°C)
Water hardness5 to 11 GH
pH6.5 to 7.3
Ammonia0 ppm
Nitrites0 ppm
Nitrates< 20 ppm
Maximum Size6 to 7 inches
Life Expectancy5 to 8 years

Red Tail Sharks and Rainbow Shark sizes are 6 inches on average, but they sometimes grow a bit longer than that.

Before becoming mature, however, identifying the gender of a Shark is quite hard. When they’re no longer juvenile, Rainbow Shark and Red Tail Shark males will have deeper coloration and more elongated bodies. Females will be slightly plumper.

Tank Size And Decorations

Because of their active swimming ability and semi-aggressive attitude, Sharks need lots of space.

A minimum of 55-gallons is a good choice for a single Shark and other community fish. Keeping 6 to 8 of them, especially with other species of fish, would need a 75-gallon tank. Giving them lots of space will ensure a low level of stress among all fish. Make sure the tank is long as these fish are strong horizontal swimmers.

With that in mind, a tank lid is a must. Many casualties have been caused by Sharks jumping out of the tank for whatever reason— stress or otherwise.

Sharks would need a filter. A bubbler is not necessary if you have enough surface agitation to keep the water oxygenized, meaning your filter is creating enough current to move the surface.

As for the current itself, Sharks love a bit of movement akin to the streams they come from. Medium current is enough.

And since they come from tropical waters, a heater is important especially if you live in a cold place where maintaining the ideal temperature is hard. If you have ambient heating that reaches 75°F and upwards, that can be enough as long as the fluctuation is not extreme throughout the day.

The usual substrate for Sharks is sand as they love to dig and burrow underneath it. Bigger particles might hurt the Sharks and make them unable to reach food underneath.

Aesthetic-wise, most hobbyists who have Sharks prefer white sand to be able to see the fish’s magnificent black color. 

Since Sharks are loners, it’s apt to give them lots of tunnels and caves to hide in. You can buy these from your favorite pet stores or create them out of PVC pipes and clay or terra cotta pots. Hollow decorations also make good “homes” for them as long as they can fit their bodies inside.

Plants are a good idea as they not only provide natural filtration and oxygenation to any tank, but they also serve as great hiding places for more shy or bullied Sharks (or their victims). The Amazon Sword, Hornwort, Java moss, and Java fern are easy to keep.

Driftwood is a good idea as it serves as a hiding place, a resting place, and a source of healthy tannins that detoxify your water. As with other decor and caves, file or cut sharp edges to prevent accidents.

Provide medium lighting for your aquarium just to help you maintain it. Some Sharks may not like bright lights.

Rainbow Shark And Red Tail Shark Diet

In the wild, Sharks eat smaller fish, algae, and live food such as insects and worms.

Rainbow Sharks and Red Tail Sharks are omnivorous. You can feed them a diet of algae wafers, live or frozen food, cut up or boiled vegetables, crustaceans (such as brine shrimp) and, sinking pellets. They can also survive on the natural algae growing in your tank, as well as detritus accumulating on the substrate.

Since these fish are bottom feeders, the best food for them is the sinking kind. You may have to weigh food down with a skewer or fork if the food, such as a vegetable, tends to float. Also, remember not to feed them too closely with smaller fish as they latter might get chased.

Sharks are fed once or twice a day. Too much is overfeeding and leads to swim bladder disorder. If your Shark is a heavy feeder, you can skip feeding once a week to keep the food in its digestive tract moving.

On the other hand, you might not see your Shark feeding at all. Should you be concerned? Our blog post “5 Reasons Why Your Red Tail Shark Is Not Eating” will help you to identify that. It also has tips on how to get your Shark to eat if it looks like it has no appetite.

For more tips on feeding, such as alternative food and helping picky Sharks to eat, you may take a look at our blog post “Is It Healthy For Rainbow Sharks To Eat Tropical Flakes?

Red Tail Shark And Rainbow Shark Tank Mates

Rainbow Sharks and Red Tail Sharks don’t like seeing other fish that look just like it. It may feel threatened and attack that fish. So if you want to keep Sharks, either keep just one in a community tank with other fish or keep them in a group of 6 to 8 Sharks.

A community tank with one Shark can have these for tank mates:

  • Danios
  • Rasboras
  • Barbs
  • Gouramis

Because of its semi-aggressive behavior and habit of creating a hierarchy when in groups, Sharks are often compared to Cichlids.

Curiously, these two species can be kept together since Sharks can hold their own inside a Cichlid tank. However, there are some conditions for them to be peaceful. You can read that on “Can A Red Tail Shark Live With Cichlids?“.

As for other types of fish, know that compatibility starts with making sure they thrive in the same water parameters. Other basic factors include size, temperament, and schooling behavior.

For example, Neon Tetras are too small for Sharks as we mentioned in “Can Glofish Live Safely With Neon Tetras?”. Even if kept in schools, Tetras will become food for the bigger Rainbow Shark or Red Tail Sharks.

Get more tips on Shark tank mates from our posts “Is It Safe To Keep Rainbow Sharks With Goldfish?“, “Can Glofish Live With Mollies?” and “Is It Safe For Catfish To Live With Rainbow Shark?“.

Common Rainbow Shark And Red Tail Shark Diseases

Even with your best efforts, problems might arise. Stay informed so you can watch out for these:

  • Swim bladder disorder – we mentioned this earlier as causing Sharks to find it hard to swim uprightly. The swim bladder is the organ that controls a fish’s buoyancy, and any abnormality will be evident in their balance and abdominal size (it will be swollen).

Need help with SBD? We discuss causes and treatments in “Is Your Red Tail Shark Swimming Funny And Acting Strange?”.

  • Fin rot – this may be caused by infection from wounds if your Shark was attacked by a tank mate. It may also be caused by a type of fungus or ammonia burn. It’s characterized by torn or decaying fins, causing it to look cut off or missing.

It’s normal to be concerned for those fins where the Shark got its name from. But they will grow back if given proper treatment. Find out how on “Do Rainbow Shark Fins Grow Back?”.

  • Parasites – the white (ich) or gold (velvet) grain-like spots on your fish are itchy parasites that multiply rapidly. They’re contagious to other fish in the tank and may infect a fish’s gills if not treated promptly. Usually, this is picked up from new fish introduced to a community tank.

Fortunately, there are many treatments available for ich or velvet. It’s also important to quarantine new fish in a separate aquarium before introducing them to the main tank.

Owners take pride in the rich black color of the Shark’s body. But when it starts to fade, it’s an indication of failing health. Check out our discussion on this topic in “Is Your Rainbow Shark Losing Color? This Might Be Why” so you’ll know what to do.

If your Shark looks lethargic, inactive, or sickly, you may want to check out the list we have on “5 Reasons for an Inactive Rainbow Shark (And What To Do)”. The tips in these might just help save your pet’s life.

Most of these diseases can be attributed to stress, and the first possible cause to check would be your water parameters. Refer to our table above for the proper ranges. Ammonia or nitrite

reading of more than 0 ppm should prompt you to do at least a 50% water change immediately.

A tank mate may also be stressing your Shark out. Be prepared to separate a bully if it’s causing too much damage in your aquarium.

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