Will Betta Fish Kill Mollies: (Discover the Truth!)

Will betta fish kill mollies? Betta fish and mollies are both popular choices for aquarium enthusiasts, but there is a common misconception that betta fish will kill mollies if kept together. This article will explore the truth behind this belief and provide valuable insight for those considering keeping these two species together in a shared tank.

Many aquarium owners are drawn to betta fish’s vibrant colors and unique personalities. At the same time, mollies are favored for their peaceful nature and ability to thrive in a community tank. However, rumors have circulated that Siamese fighting fish are aggressive and territorial, posing a threat to mollies if they are housed together.

We will examine bettas and mollies’ behavioral characteristics and provide information on their compatibility in a shared environment. Additionally, we will offer tips and strategies for maintaining a harmonious tank environment if you choose to keep these two species together.

Join us as we dispel the myths and discover the truth about whether betta fish will kill mollies in an aquarium setting. 

Can Betta Fish Live With Mollies?

The short answer is maybe, but it could be better. While some aquarists have successfully kept Bettas and Mollies together, it’s generally not recommended for several reasons:

Temperament: Bettas are known for their territorial and aggressive behavior, especially towards males of other species and fish with similar fin shapes. Mollies, while peaceful themselves can be nippy, and their vibrant colors can further trigger the Betta’s aggression.

Fin nipping: Mollies are known for their playful and inquisitive nature, which can lead to fin nipping on the Betta’s long, flowing fins. This can cause stress, injury, and even death for the Betta.

Water requirements: Mollies prefer slightly brackish water (a mix of freshwater and saltwater), while Bettas thrive in freshwater. While both can adapt to various conditions, long-term compatibility can be challenging.

Tank size: A large, well-planted tank (at least 20 gallons) is recommended to minimize aggression and provide enough space for both species. This allows the Mollies to hide and escape from the Betta’s territoriality.

Will Betta Fish Kill Mollies or Be Good Friends?

Can a Betta Kill a Molly Fish? Betta fish and mollies are not typically compatible with tankmates. While Bettas can be aggressive, it’s not guaranteed they’ll kill a Molly. 

Conversely, mollies are known to be social and community-oriented fish that thrive in groups. Their gentle nature makes them vulnerable to the aggressive behavior of bettas.

In a shared tank, the bettas will likely see the mollies as a threat and resort to attacking them. However, every fish has its personality, and there may be instances where bettas and mollies coexist peacefully.

Betta Fish Not Eating and Laying at Bottom

Nevertheless, keeping bettas and mollies together is generally only advisable if the tank is huge and heavily planted, providing enough hiding spaces for the mollies to escape aggression.

It’s essential to consider the compatibility of fish species before introducing New Fish into the same tank to ensure the well-being of all the aquatic inhabitants. 

Do Bettas and Mollies Make Good Tankmates?

No, Bettas and Mollies are not generally considered ideal tankmates. While it’s not impossible to make it work in some cases, several factors make them incompatible:

1. Temperament:

  • Bettas: Known for their territoriality and aggression, especially towards males and fish with similar fin shapes.
  • Mollies: Generally peaceful but can be playful and nippy. Their bright colors and active behavior can trigger a Betta’s aggression.

2. Fin nipping:

  • Mollies: Naturally curious and may nip at the Betta’s long, flowing fins, causing stress and injury.

3. Water preferences:

  • Mollies: Prefer slightly brackish water.
  • Bettas: Thrive in freshwater. While both can adapt to various conditions, long-term compatibility can be challenging.

4. Tank size:

  • large, heavily planted tank (at least 20 20-gallon tank) is recommended to minimize aggression and provide enough space. This allows the Mollies to hide and escape the Betta’s territory.

Overall, the risks outweigh the benefits in most cases. If you’re considering housing them together, carefully consider these factors:

How to Make Mollies and Bettas Compatible

Making mollies and bettas compatible is a delicate task, and it’s important to know that it’s only sometimes guaranteed to work. Bettas, especially males, are known for their territorial and aggressive behavior, which can clash with the more peaceful nature of mollies. However, there are steps you can take to increase the chances of success:

1. Choose the Right Betta:

  • Gender: Opt for a female betta. While not eliminated, they are less aggressive than males.
  • Personality: Observe Betta’s behavior at the store. Look for less flared-up ones and less interest in other fish.

2. Spacious and Well-Decorated Tank:

  • Size: Aim for a minimum of 20 gallons per Betta and 10 gallons per Molly. A larger tank provides more territory and reduces the chance of encounters.
  • Decoration: Create plenty of hiding spots and swimming space for both species. Use plants, rocks, and driftwood to break up lines of sight.
  • Water Parameters: Ensure the water parameters suit mollies and bettas. Research their specific needs and adjust accordingly.

3. Introduce New Fish Carefully:

  • Acclimation: Acclimate each fish to the tank water slowly and separately to minimize stress.
  • Adding Sequence: Introduce the mollies first, allowing them to establish their territory. Add the Betta later, preferably after the lights have been out for a while, so it’s less likely to be seen as a threat.

4. Monitoring and Adjustments:

  • Close Observation: Keep a close eye on the new tank for signs of aggression, fin-nipping, or stress. Be prepared to separate the fish if necessary.
  • Additional Hiding Spots: If aggression occurs, add more hiding places to give the mollies more options to escape.
  • Consider Alternative Tank Mates: If the aggression persists, finding different tank mates for the Betta or rehoming the mollies might be best.

Additional Tips:

  • It’s essential to perform regular water changes to avoid additional stress factors.
  • Feed a high-quality diet to keep all fish healthy and less likely to compete for food.
  • Don’t overcrowd the tank. Stick to the recommended number of fish based on your tank size.

Remember, even with careful planning, there’s no guarantee that mollies and bettas will be compatible long-term. It’s an ongoing process that requires monitoring and adjustments. Be prepared to adapt your plan or make changes if necessary.

Can Molly Fish Live with Betta: Tank Setup

Molly fish and bettas can live together in the same tank, but some significant considerations must be remembered. It is essential to provide enough space for both fish to establish their territories and avoid aggressive behavior.

A 20-gallon tank is recommended for housing both molly fish and bettas together. The tank should be heavily planted with places for bettas to hide and seek shelter. The water temperature should also be maintained between 75-82°F, which is suitable for both species.

Monitoring the water parameters and ensuring they suit molly fish and bettas is also crucial. Providing a varied diet and monitoring the behavior of both fish will help ensure a harmonious cohabitation.

With the proper tank setup and careful monitoring, molly fish and bettas can live together peacefully and create a visually appealing and dynamic aquarium display.

NOTE: Male mollies can become more aggressive than female mollies, particularly towards each other. Even if they don’t bother your Betta, the fighting among male mollies can stress it, and it’s best to prevent that.

Why You Should Avoid Balloon Mollies

It would help if you avoided Balloon Mollies for several reasons. Firstly, their genetically modified, rounded appearance, achieved through selective breeding, can lead to health problems and reduced quality of life.

The distorted body shape of Balloon Mollies can cause issues with swimming and mobility, leading to decreased activity and potential discomfort. Additionally, their unusual body shape can make it difficult for them to breed and give birth naturally, leading to possible reproductive issues.

Furthermore, the genetic manipulation required to create the Balloon Molly’s unique appearance can weaken their immune systems, making them more susceptible to diseases and illnesses.

Overall, the ethical concerns surrounding the breeding and keeping of Balloon Mollies and the potential health and welfare issues these fish may face make them a species to avoid when choosing fish for your Dalmatian mollies aquarium. Many other types of fish are more suitable for keeping and have fewer associated problems. 

Ideal Tankmates for Your Betta

Choosing the ideal tank mates for your Betta can be tricky. Bettas are known for their aggressive tendencies, especially towards other male fish of similar size and color.

However, a variety of peaceful fish and invertebrates can make great tank mates for your Betta, as long as you take the time to choose compatible species and provide an appropriately sized and decorated tank.

Here are some of the best tank mates for bettas:

  • Snails: Mystery snails, nerite snails, and Malaysian trumpet snails are excellent betta tank choices. They are peaceful scavengers that help clean your separate tank by eating algae and detritus. 
  • Shrimp: Ghost shrimp, cherry shrimp, and amano shrimp are popular betta tank choices. They are too small to be seen as a threat by most bettas and will help keep your tank clean by eating algae and biofilm. 
  • Corydoras catfish: Corydoras catfish are peaceful bottom feeders that will not bother your Betta. They come in various colors and patterns and are fun to watch as they scavenge for food at the bottom of the tank. 
  • Otocinclus catfish: Otocinclus catfish are small algae eaters that are safe for betta tanks. They are shy fish, so they are best kept in groups of three or more. 
  • Harlequin rasboras: Harlequin rasboras are small, schooling fish too small to threaten your Betta. They are peaceful fish that will add color to your tank. 
  • Ember tetras: Ember tetras are another excellent choice for betta tanks. They are peaceful fish that are easy to care for and come in various colors. 
  • Neon tetras: Neon tetras are classic aquarium fish known for their bright colors. They are peaceful fish that are easy to care for and make a great addition to any betta tank. 

When choosing tank mates for your Betta, it is essential to keep the following things in mind:

  • Tank size: The larger the tank, the more fish you can safely keep together. A 10-gallon tank is the minimum size for a betta and a few tank mates.
  • Water parameters: Ensure your tank mates have the same water parameters as your Betta.
  • Temperament: Choose peaceful tank mates that do not bother your Betta.
  • Decoration: Provide plenty of hiding places for your Betta and tank mates. This will help to reduce stress and aggression.

You can create a beautiful and thriving betta community tank with careful planning. Just be sure to research and choose compatible tank mates to help your Betta live a happy and healthy life.

Is it Better Keeping Betta Fish with Guppies?

Keeping Betta fish with guppies can be tricky due to the different temperaments and compatibility of the two species.

Betta fish are known for their aggressive nature, especially towards other male Betta fish and brightly colored freshwater fish with long fins, like guppies. However, with careful monitoring and a well-maintained tank, Betta fish and guppies can coexist peacefully.

It is essential to provide plenty of hiding spots and live plants in the tank to give both species a sense of security and territory. It’s also crucial to keep an eye on the behavior of the Betta fish and the guppies and be prepared to separate them if any aggression or bullying occurs.

Overall, with proper care and attention, keeping Betta fish and guppies together in a community tank is possible. Still, it’s essential to be aware of the potential challenges and be ready to intervene if necessary. 

What fish can mollies not live with?

Avoid aggressive fish like cichlids, fin nippers like barbs, and slow-moving fish like angelfish when pairing mollies. Their active nature and nibbling habits can cause stress or fin damage. 

Can a Betta Kill a Molly Fish?

Yes, a Betta fish can kill a Molly fish. Bettas are known for their territorial behavior and aggression, and they may attack and injure or kill other fish in their tank.

Can betta fish mate with Molly?

No, bettas and mollies are different species and physically incompatible for breeding. Their reproductive behaviors and anatomy differ significantly, making successful mating impossible.

Can male bettas live with mollys?

Cohabitation can be tricky! While some Bettas tolerate Mollies, their compatibility depends on individual personalities and tank setup. Aggressive Bettas or long-finned Mollies might clash. So, it is best to keep only one male per tank.

What are the predators of Molly fish?

In the wild, Mollies face a diverse buffet of predators: larger fish, aquatic insects, birds like egrets, reptiles like alligators, and even amphibians like bullfrogs. Stay vigilant, little fish!

Can female betta fish live with mollies?

While possible, success depends on factors like tank size, personalities, and fin type of molly. Female Bettas can be territorial, and long-finned Mollies might trigger aggression.

What size tank is best for Betta with mollies?

A 20+ gallons tank is ideal for Betta-Molly pairings. This provides ample space for both species to thrive, reduces territorial disputes, and gives Mollies room to swim freely. Successful cohabitation depends on individual personalities and tank setup, so monitor closely and adjust if needed.

Can Mollies Live With Female Bettas?

Maybe, but it’s tricky! Female Bettas can be territorial, and long-finned Mollies might trigger aggression. Choose a spacious tank (20+ gallons) with lots of hiding spots and opt for peaceful Molly species like sailfin mollies.

What are the reasons why mollies may good tankmates?

Mollies make excellent tankmates for their peaceful nature, vibrant colors, and hardy resilience. They’re active algae nibblers and easy to care for, making them ideal for beginners. Plus, their livebearing abilities can add a touch of wonder to your aquarium!

What fish can live with bettas?

Choose peaceful and slow-moving tankmates for Betta fish, such as small tetras, rasboras, or Corydoras catfish. Avoid aggressive or fin-nipping species to ensure a harmonious community aquarium.

Can Betta fish live with other fish in the same tank?

Yes, Betta fish can live with compatible tankmates such as peaceful tetras, rasboras, or Corydoras catfish. However, monitoring their behavior and ensuring a suitable environment is crucial.

Are there reasons mollies may make good tank mates for bettas?

Mollies may make good tank mates for bettas due to their similar water parameter preferences and compatibility in terms of temperament. However, individual fish behavior can vary.

Are mollies omnivores?

Yes, mollies are omnivores! They enjoy a diverse diet of both plant and animal matter. In the wild, they munch on algae, biofilm, small insects, and even zooplankton. Aquarium fish thrive on a mix of high-quality flakes, pellets, live or frozen food like brine shrimp, and even blanched vegetables like cucumber or zucchini.


So, does betta fish kill mollies? In conclusion, caring for different fish species can be a rewarding experience, but it requires careful consideration and research. While betta fish and mollies are both beautiful and popular choices for aquariums, it’s essential to understand their compatibility. Mixing betta fish with mollies can lead to aggression and stress among the species, and in some cases, the betta fish may harm or even kill the mollies. Therefore, if you plan to keep these fish together, creating a well-balanced and adequately sized environment that promotes harmony is crucial. By providing appropriate water conditions, you can minimize the chances of encountering issues such as “Will betta fish kill mollies.”

You might also like

About Me

I am the founder of, a devoted wife and mother, and an avid fish enthusiast. My aim is to assist fellow fish lovers worldwide in understanding how to properly care for and breed their pet fish.

Recent Posts

Stay Updated

Get outdoor trends, data, new products, and tips delivered to your inbox.

error: Content is protected !!
Scroll to Top