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Can You Keep A Killifish And Betta In The Same Tank?

Betta fish are one of our favorite species of fish by far and their popularity within the fish keeping hobby continues to go from strength to strength too.

The trusty betta fish is currently the second most commonly kept species of fish second only to goldfish so we constantly see people asking questions about keeping bettas in their tanks.

Although killifish were once very niche fish, they have seen a steady increase in their popularity over the last couple of years as the species with some types of killifish being extremely popular now.

As you can probably guess, we do see some people asking about keeping killifish and betta fish in the same aquarium as each other each month so we have decided to make that the main focus on today’s article.

Our hope is that we will be able to help as many of our readers who are thinking of keeping bettas and killifish in the same tank as possible.

Many of the discussions on social media are just an outright “don’t do it” but some of the more experienced fish keepers out there can keep bettas and killifish in the same tank with minimal issues.

Are Betta Fish Aggressive?

The main concern that people have when mixing bettas and killifish is aggression.

Betta fish are well known for being an aggressive species of fish, especially the males.

Males will often fight each other to the death if they are placed in the same tank so it’s no surprise that many people believe that bettas will also be aggressive towards other species of fish.

However, this isn’t always the case.

Not all male betta fish are hyper aggressive and female betta fish do tend to be less aggressive than males but most male and betta fish are still considered to have above average levels of aggression as far as fish go.

This can make it more difficult to keep a betta in a community tank but with the correct precaution taken, you can minimise and in some cases, totally avoid problems with aggression.

Are Killifish Aggressive?

The problem with the term “killifish” is that there are a number of types of killifish out there with some being far more aggressive than others.

On top of that, some killifish like the Blue Gularis can end up growing to around six inches making them large enough to try and eat a betta fish in their tank if they choose.

You can flip that over to the smaller killifish species though as something like a clown killifish can live with a betta in the right tank setup with minimal problems.

This is why you often see so many people on social media instantly telling other fish keepers not to keep killifish and bettas together, there are just a large number of different types of killifish that makes it difficult to pair them up correctly.

Can Killifish Live With Bettas?

The answer to this question is both yes and no.

As we’ve already mentioned, there are a large number of different types of killifish out there which makes it difficult to give a straight forward answer.

We have seen people keeping clown killifish and bettas together in the same aquarium with great results but we have also seen people trying to keep other types of killifish and bettas together with disastrous results.

The best way to see if you can keep killifish and bettas together is to do your own research on the specific type of killifish that you are thinking of keeping.

If you do want a quick and easy option though then the clown killifish would always be out default recommendation.

Alternative killifish options include the red-striped killifish and the golden wonder killifish but these can be hit and miss and although many show minimal aggression, other, especially males can be aggressive towards their tank mates.

What Size Tank Do You Need To Keep Killifish With Bettas?

The size of the tank you need to keep killifish and bettas in the same tank will usually depend on the type of killifish that you are keeping.

A smaller killifish like a clown killifish can work in a 20-30 gallon tank with a betta provided you implement the steps that we will cover later in the article to help minimise aggression in the tank.

Red-striped killifish and golden wonder killifish are slightly larger than a clown killifish too so they will be closer to the 30 gallon tank size minimum.

You also have to realise that some types of killifish like to school where as others don’t. If you do go with a killifish that is a schooling fish then you will usually have to keep around six of them in the tank meaning you need a larger tank size.

Does My Tank Need Fish Hides And Plants?

If you want to keep killifish and bettas together in the same aquarium then we recommend that you use a variety of plants, fish hides and other items in your tank to help reduce aggression.

By using these items, it will give your fish a place to retreat to if they feel threatened or need some time away from each other.

It can also help to spread out aggression by giving each fish their own space in the tank.

Some good plant options that we recommend include java fern, anubias and cryptocoryne while some good fish hide options are coconut shells, pieces of wood and even upturned flower pots.

You don’t need to go overboard with these items, a few strategically placed plants and fish hides should suffice.

How To Keep Killifish And Bettas In The Same Tank!

You should always try to select female bettas and killifish if possible as they tend to be less aggressive than their male counterparts.

Always try to go with a non-aggressive killifish if possible such as a clown killifish but other types of killifish can work.

Just keep in mind that with killifish, the brighter and more beautiful their colors, the more aggressive they tend to be so always research the specific type of killifish you want to keep.

We would always recommend that you use a larger than needed tank to offer both species plenty of space.

Our rule of thumb would be to take the minimum tank size for the type and number of killifish you plan to keep and then add 20 gallons to it. Although its not exact, it offers a good ball park figure to aim for.

Make sure you have plenty of hides and sight breaks in the tank to make sure that your fish are able to get away from each other and hide if needed.