Is It Safe To Keep Rainbow Sharks With Goldfish?


Goldfish are always in danger of being bullied or nipped on, that’s why it’s they’re usually kept with their kind. At the same time, Rainbow Sharks are known to be semi-aggressive. And yet some people keep them together in the same aquarium.

Can a Rainbow Shark Live with a Goldfish?

Believe it or not, Goldfish are actually related to Rainbow Sharks in that they are both types of Carp. But being related doesn’t necessarily mean they’re automatically compatible.

While Rainbow Sharks and Goldfish can cohabitate one single tank, it is complicated and very difficult. Many conditions have to be met, and even if they are so, there is still the possibility that your Rainbow Shark will hurt your Goldfish especially when they reach maturity. Therefore, it is not recommended.

Here are the reasons why these two species are not compatible:

Reason #1: Water temperature differences

Goldfish love cooler waters with a temperature of about 65 to 74 deg Fahrenheit, while the Rainbow Shark prefers warmer waters around 77 to 78 deg Fahrenheit.

Forcing a fish to live in water too far from its preferred temperature would make it prone to diseases. Goldfish will definitely suffer in the upper 70s, especially with the water having less oxygen.

On the other hand, a scientific study of the Albino Rainbow Shark (Leggatt, 2018) published by the NRC Research Press in 2019 revealed that it starts to lose its appetite and activity in water that is around 64 to 65 deg Fahrenheit. This study was done to find out if the fish can tolerate the cold waters of Canada.

Reason #2: Their personalities usually clash

Mature Rainbow Sharks are known for their volatile temper. One moment they can be lazy and languid and the next they’re chasing some poor fish all around the tank. That’s because they love their solitude and territory and some fish was bold enough to come near it.

On the other hand, Goldfish are very curious fish. People love them for their personality, but Sharks see them as invaders.

Is it Safe To Keep Rainbow Sharks With Goldfish?
Is it Safe To Keep Rainbow Sharks With Goldfish?

And so, Goldfish are often chased by Rainbow Sharks for encroaching their territory. They will predictably come near the Shark’s hideout and in turn, the Shark will have to drive them away. This is why the Goldfish may have little nips and tears in its fins now and then.

Is There a Way for Rainbow Sharks to Live With Goldfish?

It’s not impossible, but it’s not for the beginner. And even with the best of efforts, there is no guarantee that it will work. That being said, the tanks that do successfully have both species in them have the following conditions:

Condition #1: Tank setup matters

Rainbow Sharks are often kept alone, and Goldfish are always kept in pairs. If they have enough tank space between them, a temperature that’s comfortable for both species (see above), plus lots of plants and hideouts, they may find a harmonious balance in the aquarium.

Even the shape of the tank should be big enough for both. Goldfish would need a taller tank because of its size, and the Rainbow Shark would need a wide base to be able to swim around.

This means a tank size of at least 75 gallons for 1 Shark and a pair of Goldfish. Any more than that and you’ll need a bigger tank.

If there are other kinds of fish, that tank size should even be bigger.

Condition #2: Size matters

Goldfish love to put things in their mouths. They even love to chase stuff around the tank just so they can eat it. As long as they can fit– food, plants, smaller fish– they’ll try to swallow it. So don’t put juvenile Rainbow Sharks with adult Goldfish, especially Goldfish that are 6 inches or bigger.

Looking at the bright side, that also means that Goldfish are not picky with food and they won’t have problems getting to them, either, if you only have one Shark. This is significant because one of the conditions in putting Goldfish with another is that they don’t outcompete the Goldfish for food.

Another positive is that these two species don’t stay in the same water column. Goldfish love staying in the middle and top of the water column, while Sharks love to stay in the bottom mainly to forage for scraps of leftover food and algae.

Condition #3: Numbers matter

Too many Goldfish inside a community tank will cause havoc on the water chemistry as they are very messy. Although Rainbow Sharks sort of “clean up” the tank of algae and detritus, ammonia spikes would make both of these fish sick.

Goldfish
Numbers of Goldfish matter

When they are kept together, there are only 1 to 3 pairs of Goldfish in a big enough sized tank (see Condition #1 above). A good filter and lots of live plants are usually in the tank as well.

Condition #4: The type of Goldfish matters

Fancy Goldfish will be able to tolerate warmer waters than the common Goldfish can. The good news is that the Rainbow Shark can indeed go lower to 73 or 74 deg Fahrenheit to compromise. However, stress and irritation should be detected early in the Shark as he can let out his frustrations by attacking his tank mates– the Goldfish.

What are the compatible tank mates for Rainbow Sharks and Goldfish?

As a general rule, Rainbow Sharks don’t like to be kept with fish that look like them– which means Carps with long, torpedo-like bodies or any fish that has the same-looking red fins and tails. This is because the Shark will see them as threats to itself.

If you heed our advice and don’t force the issue of the Rainbow Shark-Goldfish combination, there are lots of other fish that you can consider to become tank mates for each of these. Check them out on these lists if you want to try them instead:

For Rainbow Sharks:

  • Danios
  • Plecoes
  • Rasboras
  • Rainbowfish
  • Barbs
  • A large group of other Rainbow Sharks
Rainbow Shark
Rainbow Shark fish

Goldfish are the opposite. They should be kept with only Goldfish or closely-related species and fish that can tolerate the same cool waters:

  • Koi
  • Dojo Loaches
  • Cold Water Minnows
  • Ricefish

You may notice that the main considerations for these are size, temperament, and water temperature compatibility. If you want to learn more about getting compatible tank mates for your fish, you can read all about it on our post here.

Final Thoughts

Even if you follow all the conditions listed above, there’s still no guarantee that the combination will work. We understand if you want to try something different or put them in the same tank because they look good together, but even experienced fishkeepers advise against putting these two species together.

It’s a big risk, and we advise you to either not attempt this or, if you have advanced experience in fish keeping (or you’re already in that situation), keep a backup tank in case the combination doesn’t work. You might need to re-home the Rainbow Shark if things go downhill.

If this happens, you can bring it to a pet store for credits or give it to a friend.

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