Are Rainbow Sharks Aggressive

Rainbow sharks can be aggressive but it’s dependent on their tankmates. In general, they aren’t aggressive with fish that live in the middle and top of the tank, but can be very aggressive with bottom feeders such as catfish and plecos.

Rainbow sharks are amazing fish.  Their colors are beautiful with a dark gray body and red fins and can grow to about 6 inches long.  They are also available in an albino form with a light pink body and red fins.

They are active swimmers who will take advantage of open spaces in your tank.

It’s great fun watching them dart around the tank and many who keep them say they are by far their favorite and most entertaining fish they have. They also love to hide in decorations and rocks and will hangout under and within plants.

But they can be aggressive and territorial depending on many factors which will be explained within this article.

So are Rainbow Sharks Aggressive?  The answer is, as with many questions in this hobby, “it depends.”

MerlinSenger [CC-BY-SA-3.0]
MerlinSenger [CC-BY-SA-3.0]

Rainbow Shark Aquarium Setup

One of the biggest factors in rainbow shark aggression is the tank setup.  Rainbow sharks need lots of space in a big aquarium. They should be kept in a minimum of a 55 gallon aquarium, preferably larger.  The other important factor is the surface area of the tank (and the resulting bottom area).  Larger areas provide more space for the sharks.

They also require lots of open areas to swim and burn off energy. But they also require a heavily decorated tank. Provide lots of rocks, caves, plants, and driftwood. When they aren’t swimming, they like to hide out in little nooks. Many rainbow sharks will become attached to some of their decorations and hiding places which will make them territorial towards some other tank mates.

Rainbow Shark Tankmates

There are several appropriate tankmates for rainbow sharks. In general, they can be kept with other fish of similar size and similar aggression, but there’s a bit more too it.

Other Freshwater Sharks

Rainbow sharks don’t get along with other freshwater sharks, including other rainbow sharks.

Redtail sharks, bala sharks and siamese algae eaters all bring out the worst in rainbow sharks. They feel threatened that they will lose food or territory and become aggressive.  They will readily fight to maintain “control” over their favorite hiding spots and sometimes several feet of the aquarium which they consider to be theirs.

It can be possible for rainbow sharks to live in the same aquarium as other freshwater sharks, but this typically requires several hundred gallon tanks and is beyond the realm of possibility for most hobbyists.

Joeysaad [CC-BY-SA-3.0]
Joeysaad [CC-BY-SA-3.0]

Good Partners

Gouramis, barbs, rasboras and danios are all suitable tankmates for rainbow sharks.  

Gouramis body shapes tend to be very different from freshwater sharks.  As a result, rainbow sharks don’t perceive them as threats.  No threat usually means no aggression.

Barbs, rasboras, danios, and tetras are all smaller schooling fish with rasboras and danios being from the same habitat/region as rainbow sharks. Rainbow sharks tend to get along well with most schooling fish that spend their most of their mid-tank level or upper-tank level. In this case, however, some of the more nippy schooling fish like tetras and rasboras can actually torment the rainbow shark.

As with all fish in your aquarium, everyone should be continuously monitored to make sure everyone is living together peacefully and no one is getting bullied or injured.

Bad Partners

As mentioned above, rainbow sharks don’t get along with other rainbow sharks or other freshwater sharks. They will also fight with many catfish and other bottom dwellers.  This eliminates most plecos and most other algae eaters such as the oto catfish.

They occupy the same territory as rainbow sharks and are often perceived as threats.

Additionally, bottom dwellers that are smaller than rainbow sharks, such as cory cats and oto cats, will not win in the inevitable fight.  They can be severely injured or even killed.

These fish tend to fall into the “don’t even try it category” except in tanks that are several hundred gallons.  Even then, they still should be monitored for aggression.

In-Between Partners

Loaches can be very hit or miss.  

Some get along great, some don’t.  Loaches grow to a similar size as rainbow sharks and their colors are usually very different.  They can have a similar temperament, but tend to be slightly less aggressive.  The difference being that loaches can typically hold their own against and aggression.

If you plan to keep loaches with rainbow sharks, the loaches should be added to the tank first.  This will give them time to establish their territory and maybe get a bit of a size advantage on the soon to be added shark.  As with every case, keep an eye on things and make sure everyone is cohabitating peacefully.