The betta fish has been the second most commonly freshwater fish second only to the goldfish for years now with a huge number of people keeping bettas in their tanks.
The rainbow shark has seen a slight increase in popularity recently but it is still a relativley niche species to keep but we have noticed a number of people suggesting it as a potential tank mate for your betta fish.
The logic is that the betta fish usually occupies the upper and middle water layers in your tank and the rainbow shark usually ocupies the lower layer so the aggression levels of the two fish should rarely have a chance to collide.
Due to this, there have been a number of people reaching out and asking questions about keeping a rainbow shark and a betta fish in the same aquarium recently so we wanted to publish this article.
Are Betta Fish Aggressive?
Male betta fish can be hyper aggressive in some aquarium setups and have above average levels of aggression in other tank setups. Female betta fish do tend to be less aggressive than males but they can still have higher than average levels of aggression, especially in smaller community tanks.
Betta fish are prone to fin nipping and can be particularly aggressive towards other long-finned or brightly coloured fish so they are not the best tank mates for a lot of species.
Male betta fish can also establish what they perceive as their territory in their tank and they will attack anything that enters it.
On the flipside of that though, there are a very small number of totally placid betta fish out there that can definitely work in community tanks but unfortinately, you usually don’t know until you have already added the fish to your tank to see how it reacts to your own fish.
Are Rainbow Sharks Aggressive?
Although rainbow sharks are not as aggressive as betta fish in most tank setups, they can still be an aggressive species with above average levels of aggression towards their tank mates.
Most people within the fish keeping community seem to consider rainbow sharks as moderately aggressive and they can end up nipping and chasing their tank mates in some situations.
Can You Put Rainbow Fish With Betta Fish?
The majority of people do not recommend keeping rainbow fish with betta fish as they can be quite aggressive towards each other, especially in smaller tanks.
Still, there are a number of people keeping rainbow fish and betta fish in the sane tank without issue but these do tend to be more experienced fish keepers who have previous experience with keeping betta fish.
We will go over some of the steps that you are able to implement in your aquarium to make it as friendly as possible for keeping bettas and rainbow sharks together with minimal issues with aggression.
What Tank Size Do You Need For Rainbow Sharks And Bettas To Be In The Same Tank?
Although betta fish can live in smaller tanks with aquariums of between five and ten gallons being commonly used, an adult rainbow shark usually needs an aquarium that is around the fifty gallon mark.
Sticking to this fifty gallon and up tank size can reduce the problems with aggression between your betta fish and rainbow shark as both fish have plenty of space to avoid each other.
Many of the problems that you see people having on social media who are trying to keep bettas with rainbow sharks are trying to keep them in a twenty gallon tank or even smaller.
Still, going with a larger tank and keeping it bare so both fish species can just look at each other all day is not a good idea as it invites aggression between the two but there are things you can to to reduce the chances of aggression between the fish that we will cover in our next section.
Should You Put Fish Hides In The Tank?
One of the best things that you can do when trying to keep rainbow sharks and bettas together in the same tank is to put a number of suitable hideing spots in your aquarium.
You should try to put two or three fish hides in your aquarium for each fish species which would mean having four to six different fish hides in a fifty gallon tank.
Here are the standard options for hiding spots that we would recommend in a tank with bettas and rainbow sharks in it.
There are a huge range of different fish hide options on the market with there being plenty of suitable fish hides on the market for betta fish due to their smaller fish.
One problem that you may find is that it can be a pain to find a commercial fishhide for a rainbow shark due to them being double the size of betta fish and larger than the standard fish species that fish hides are usually designed for.
Still, there are a large number of suitable DIY fish hides that you are able to use to help reduce problems with aggression between your betta fish and rainbow sharks.
Another great option for hiding spots in your aquarium are rocks as they can create a large number of small hiding spots that both bettas and rainbow sharks will be able to take advantage of.
One thing you need to bear in mind when using rocks as hiding spots is that you need to make sure they are securely placed in your tank so they do not fall over and crush your fish.
We would recommend using larger rocks as they are less likely to fall over than smaller ones but at the end of the day it is really down to personal preference.
Rocks also make excellent sigh breaks for your fish even if they are not being actively used for hiding.
Another type of hiding spot that we recommend using in your aquarium are live plants as they provide a number of benefits for your fish.
Not only do they provide some form of hiding for your fish but they also help to improve the water quality in your tank which is always a good thing.
You need to be careful when selecting live plants for your aquarium as some plants are known to be toxic to betta fish such as the common goldfish plant.
We would recommend using Java Fern, Anacharis, and Hornwort as they are all suitable for both betta fish and rainbow sharks.
You should also bear in mind that live plants will need extra care such as fertiliser and CO2 injection to ensure they stay healthy in your aquarium.
The longer the plant the better they tend to be as a fish hide or sight break though so keep this in mind too.
Driftwood is another type of hiding spot that we would recommend using in your aquarium as it provides a large number of small nooks and crannies for your fish to hide in.
Driftwood also helps to give your aquarium a more natural look which is always a good thing.
One problem that you may find with driftwood is that it can be a bit of a pain to clean as it is very porous.
You should also bear in mind that some types of driftwood can release tannins into the water which can lower the pH of your aquarium water.
We would recommend using Malaysian Driftwood as it is a good option for both betta fish and rainbow sharks.