Can Bettas And Mollies Live Together?

Wondering if bettas and mollies can live together? This guide is for you!

Bettas are some of the world’s most striking and colorful fish species. We keep them for their beauty and vibrant personalities.

You’d like to keep this pet with an equally beautiful fish species – such as a molly. But, are bettas and mollies compatible?

Can the two live together without being aggressive and antagonistic toward each other?

Bettas and mollies can live wonderfully together under the right conditions. However, knowing how territorial the betta fish is, some risks may be involved in pairing the two. The good thing is that mollies are peaceful and are unlikely to cause any ruckus in the tank. For a successful pairing between bettas and mollies, you need to consider a number of things.

To bring the two fish species together, you should acquaint yourself with the betta’s and molly’s needs and temperaments.

This post is meant to guide you on this.

bettas and mollies

Understanding Bettas and Mollies

A betta fish can live with another species only if their needs are similar. As such, it’s important to understand whether the needs of mollies and bettas align.

Let’s have a look at this in more detail.

Water Temperature

Both the betta and mollies thrive only when the water temperature is right. Conversely, if this temperature is off by a number of degrees, their immune system quickly gets compromised.

Both species of fish are easily affected by temperature fluctuations. As such, this is one of the most important considerations any keeper must emphasize.

Bettas thrive in water temperatures of 260C (780F). However, they will be fine in temperatures between 240C and 270C (760F and 800F).

On the other hand, mollies are quite the survivors as they do well in a temperature range of between 170C and 280C (620F and 820F).

From this, you can tell the two fish species will live well if the water temperature is kept between 260C and 270C (780F and 800F).

With 260C (780F) being bettas ideal temperature, this should not be much of a problem if you have the right equipment.

The pH Level

Bettas in the wild can thrive at pH levels of 6.5 to 8.5. Captive bettas are typically kept at a pH level of 7.0 to 7.5.

Mollies do well in pH levels between 7.0 and 7.8. This means there’s a comfortable middle ground of 7.0 to 7.5, where the two fish species can thrive as tank mates.

If you intend to keep bettas and mollies together, the pH level will not be a problem.

Water Salinity

Bettas are freshwater fish species in the wild or in your home. They cannot survive in a salty water environment.

On the other hand, mollies prefer slightly brackish water. So although they can live in freshwater reservoirs, they do best when the water is a bit saline.

You can do one of two things to enable your betta to live with mollies. Purchase mollies that have been bred and raised in freshwater.

A good number of breeders and pet stores actually raised mollies in saline-free water. This option means there won’t be much of a problem adding the mollies to the betta tank with freshwater.

The other option is to add a little aquarium salt to the betta tank. Recent studies have shown that small doses of this salt benefit your betta fish.

According to the International Betta Congress (IBC), small doses of aquarium salt boost your betta’s immunity.

It also makes your betta’s colors shinier and more glorious.

The method you choose to introduce mollies into the betta tank depends on what you’re comfortable with.

Go for the one that makes you and your pets happy.

Molly Fish Size vs. Betta Size

When fully grown, a molly fish will be an inch longer than a betta fish. This means that when the betta fish is 3 inches long, the molly fish will be 4.

For the two to live comfortably together, you need to consider they need a lot of space to swim, play, and carry out their activities.

A 5-gallon or 10-gallon tank may not suffice for these tank mates. Since mollies are social fish species, you’d want to consider a bigger tank – one in the range of 20 to 30 gallons.

A 25-gallon tank will give enough room for the mollies to feel safe and secure from the betta fish. In addition, it gives plenty of room for a number of mollies to live side by side with the betta.

The challenge of putting one molly in the betta tank is that the molly will be too stressed. Being social fish, mollies thrive in the presence of other mollies.

Molly Fish Lifespan vs. Betta Fish Lifespan

Under the right conditions, mollies live to the ripe old age of 5 years. This is almost the same lifespan as a betta fish, which lives between 3 and 5 years.

However, not all mollies and bettas make it this far. These species live for 2 or 3 years, although their chances significantly improve in captivity.

Mollies and bettas in the wild face many perils that severely curtail the quality of their lives.

You can expect these animals to live healthy, happy, and meaningfully with the proper care and attention in your home.

Handling Aggression in a Betta/Molly Tank

Mollies are known for their peaceful, friendly temperaments. But, unfortunately, the same cannot be said of the bettas. They are not called the Siamese fighting fish for nothing.

Betta fish sometimes gets agitated and starts chasing his tank mates around. This behavior is more common with the male betta than with the females.

If you see your betta chasing the mollies around, you need to step in quickly and resolve the situation.

Otherwise, this will likely heighten stress levels in both fish species, leading to other health complications.

First, you need to establish that the betta is actually being aggressive and not giving a temporary show of who’s in charge.

If the betta fish is hostile, it may injure the mollies. Therefore, you need to relocate them to another tank and attempt to reintroduce them later.

Hopefully, the betta fish will have calmed down and be more receptive when the mollies return.

If you don’t have room or space for a second tank on your premises, use a divider to separate the mollies and betta.

You first need to remove both fish species and clean the tank and its accessories to achieve this. After this, divide the tank and put the two species in their different compartments.

Sometimes this works: the betta accepts the mollies as his neighbors, and you can remove the divider when he calms down.

If it doesn’t calm the betta fish immediately, you should cover his tank side with plastic wrap to give him more privacy.

At times, the aggression and hostility displayed by the betta can be attributed to that particular fish’s personality and behavior.

Since there’s nothing much you can do to change him, you may sadly have to get rid of the mollies. However, you may consider introducing other tank mates, such as guppies or loaches.

Can Betta Fish Kill Mollies

Some betta fish get so aggressive that they kill smaller tank mates such as mollies. However, not all betta fish behave this way.

Every betta has a unique personality that dictates its temperament and behavior in the presence of tank mates.

You must understand your betta fish well before considering housing him with mollies. Under what conditions does your betta become agitated and aggressive?

For example, is he likely to attack a molly when he’s hungry? Bettas have been known to attack the smaller creatures in the aquarium for food.

A betta fish will attack and kill a molly under the proper condition.

However, if your betta fish is of the right temperament, there’s no reason he should not get along with mollies.

The two fish species have so much in common that they can make their aquarium the perfect home.

What Makes Bettas and Mollies Good Tank Mates?

Bettas and mollies can be great tank mates. They have a lot going for them, which makes them ideal partners in the same tank.

Here are reasons your betta and mollies can thrive together:

Their Size

Mollies grow just a little bit longer than bettas. At 3 inches long in maturity, bettas are almost the same size as mollies, 4 inches.

Although they are almost the same size, you must remember that putting the two together requires a considerably big tank.

You need a 20-gallon tank to accommodate the various needs of the two species.

Dietary Needs

Betta’s and mollies’ dietary needs are more or less similar. Although mollies are omnivores and bettas carnivores, they can survive on the same diet.

You need to provide them with food that meets their nutritional needs. For example, consider that bettas need high protein in their diets.

By providing insects and insect larvae, you’ll take care of the nutritional needs of both fish species. Mollies will supplement this diet with algae and a few plants matter.

This will not only nourish the molly fish, but will clean the aquarium, as well.

Water Conditions

Although mollies are classified as freshwater fish, they prefer living in brackish water in the wild. This tells you that bettas and mollies can live quite well if you add a little aquarium salt to the tank.

However, take care not to add too much salt as this would disadvantage the betta fish.

The other alternative is to source for mollies born and bred in freshwater. These mollies will not need to adjust much when put in freshwater betta tanks.

The good thing is that both fish enjoy the same pH and temperature conditions. Therefore, these two tank parameters will not present any problems.

How to Handle Mollies’ Fry

Mollies are livebearers – they give birth to their young. Also, the female molly can store sperm for months.

As such, don’t be surprised when a female molly gives birth to young ones months after you introduce her into the betta tank.

The birth of fry introduces a new set of challenges in the aquarium. For example, the bio-waste level will considerably rise.

Also, the space may not be adequate to accommodate the new infusion of fish. Too many fish in the same tank will compromise water quality, and could mess up the water parameters.

Here’s what you can do to ensure your betta and the mollies continue living harmoniously:

Let the Fry Be

Regardless of how many fry the mollies give birth to, don’t interfere with the tank dynamics. Instead, allow nature to take its course.

Most of the fry will be eaten by either the mollies or the betta fish. Very few, if any, will grow to maturity.

Molly fry provides ready fodder for hungry fish. Bettas are particularly good at thinning this population.

To help them achieve this objective, remove the hiding places where the fry can seek refuge. Leave the fry to their own devices and let the laws of nature take care of the rest.

Nurture the Fry

If you have a soft spot for the fry, you’ll want to protect them from their parents and the betta fish. You have to separate them from the main tank to nurture them to maturity.

However, there may be too many to keep in your home. The best option is to release them into marshes, bogs, rivers, and coastal waters.

This way, they’ll have good chances of making it to adulthood – though this outcome is not guaranteed for most of them.

Sell the Molly Fry

Instead of discarding the molly fry in the wild and leaving them to their fate, you can sell them to a willing buyer.

Alternatively, you can donate or give them away for free. This way, you can be sure that these little creatures will be well taken care of.

Keep Only Females in the Tank

Although mollies are known to be generally docile, the males can sometimes become aggressive. Putting aggressive male molly with a male betta is a recipe for trouble.

However, if the molly is docile, he can make the best betta tank mate. This is because male mollies don’t give birth to young ones.

You can also keep female mollies with bettas after ascertaining that the mollies are not pregnant.

You may have to involve an expert because mollies have been known to give birth months after being separated from the males.

Your best bet to have a fry-free tank is to keep only one sex of mollies with the betta.

If the female mollies stay for up to 2 months without giving birth, you can be sure the risk of doing so has been eliminated.

Fry Animal Feed

Some keepers use molly fry to feed their other pets and animals. Fry feed is beneficial because they are rich in protein.

What’s the Best Tank Size to House a Betta and Mollies?

Keeping your betta with mollies’ tank mates requires considerable tank space. So for the two fish species to be happy together, go for the biggest tank size you can lay your hands on.

However, we have to be realistic. Large tanks require considerable resources in terms of starting capital.

Also, they’ll take up a lot of space in your home or office. As such, you can’t go for a big tank for the sake of it.

You must factor in its cost, the cost of tooling it, and how it will fit in your premises. With this in mind, we can work with the bare minimum tank you need.

Keeping a betta fish with mollies requires a 20-gallon tank. It’s even better if you can get a 30-gallon one.

The two fish species need enough room to swim, play, and feel comfortable in each other’s presence.

This will definitely not happen if they are crowded or confined to a 5 or 10-gallon tank. With a 25-gallon tank, you can house 1 betta and up to 7 mollies.

Remember, bettas are as energetic, and they are aggressive. As such, you can’t keep two males of this species in the same tank.

It’s easier for female bettas to co-exist with mollies. Also, being less aggressive than their male counterparts, female bettas are more tolerant of tank mates.

However, suppose you have a sorority of female bettas. In that case, you need a really large tank before introducing a group of mollies.

This is because female bettas often fight among themselves to establish a hierarchical order. Although these fights don’t last long, you wouldn’t want your mollies to be caught in them.

What’s the Best Food for Mollies?

Mollies are omnivorous – they can thrive on any diet that takes their fancy. Being opportunistic eaters, they won’t have problems taking to your betta’s diet.

Your primary focus should be to get the betta fish its proper nutrition. If the betta gets any other food apart from a protein-based diet, its health is compromised.

On the other hand, you can comfortably feed mollies whatever the betta fish is eating. Then, once in a while, you can add some fiber-rich foods to the benefit of the mollies.

Mollies need plants to maintain a good internal balance. As such, consider feeding them some leafy greens.

The good thing is that the molly eats algae that grow in the tank. This is an excellent way of augmenting the betta diet while making the aquarium safe for other tank users.

So, to take care of your betta and his mollies tank mates, consider feeding them the following:

  • Live insects – blood worms, black worms, daphnia, etc.
  • Insect larvae, such as mosquito larvae
  • Frozen insects and insect larvae
  • High—quality betta pellets

How to Feed Bettas and Mollies

Because mollies are likely to outnumber your betta fish in the tank, they may eat up all his food. This will make the betta fish hostile and aggressive.

Worse, the betta fish will gradually starve and lose body mass.

As such, you’d want to devise an ingenious way to ensure your betta fish gets its fair share of every meal.

You can catch the betta in a net and feed him from here. This way, the mollies will not have access to their food.

As the betta feeds this way, drop more food into the water for the mollies to feats on.

Another alternative is to draw the mollies into one side of the tank by dropping fish food there.

Once they are safely on that side and out of the way, drop some betta pellets on the other side for the betta fish.

This ensures that both the betta and the mollies get enough to eat, and that neither species disadvantages the other.

Remember, bettas are always at risk of over-feeding. But, unfortunately, this fish keeps eating even when he’s full, putting him in real danger of developing a raft of health complications.

Feed your better a small amount of food daily. Too much food will cause trouble.

What Are Balloon Mollies and Why Should You Avoid Them?

Your betta fish can live well with different varieties of mollies.

From Sailfin Mollies and Dalmatian Mollies to Golden Mollies, Midnight Mollies, and White Mollies, the betta fish will not be short of company.

However, there’s one variety of betta fish you’d like to avoid for your betta fish tank. This is the Balloon Mollies.

Balloon mollies should not be on any list of mollies you’d like to consider as your betta fish tank mate. This is because balloon mollies are selectively bred with scoliosis, which has dire implications for this molly fish.

Because of its genetic predisposition, balloon mollies die much more quickly than other mollies. As a result, they are relegated to spending uncomfortable lives because of their malformed body structures.

It’s hard for the balloon molly to swim or give birth because its spine is deformed. For this reason, these are not the best tank mates for your betta fish.

Look for other types of mollies to give your pet betta company. Fortunately, the list of eligible candidates is not short!


When you decide to house a betta and mollies together, you need to consider a lot of things. First, because these are two different fish species, you need to plan all the tank details meticulously.

Bettas and mollies can make fantastic tank mates if the conditions are right. However, if these fish are not well-attended, you can be sure they’ll lead a chaotic life.

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