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Everything You Need To Know About Balloon Belly Molly

Everything You Need To Know About Balloon Belly Molly

Wild mollies are super hardy. They can easily adapt to even the harshest of conditions. However, the same cannot be said about artificially bred mollies like balloon belly molly marred with numerous birth defects. 

Although balloon belly mollies look nothing short of stunning, the aesthetics come at a price for these poor little guys. These fish were selectively bred to be short and round. Therefore, they have an unnatural curvature of the spine. 

As a result, they’re prone to sustain internal organ damage, which can cut their lives short dramatically. 

Personally, I don’t support buying or even raising balloon belly mollies due to the harsh life these fish lead. But if you have already brought them home, in this blog, I’ll tell you all there’s to know about these unique fish and how to give them the best life possible. 

First, let’s start with a quick introduction. 

An Introduction To Balloon Belly Molly 

NameBalloon belly molly
Scientific NamePoecilia sphenops 
Family Poeciliidae 
ColorBlack, white, yellow
Diet Omnivore 
Temperature72-82°F (22.22-27.7°C)
Minimum Tank Size 30 gallons

People have raised mollies for more than a century – especially the sailfin mollies. But balloon mollies were introduced only a few decades ago. 

These are, in fact, the result of the hybridization of the popular sailfin molly. In a sense, you can call the ‘man-made’ fish. Therefore, they’re not found in the wild. 

There are dozens of unique molly strains available today, like dalmatian molly and harlequin sailfin molly. But none look as striking as the balloon belly molly. 

These fish were specifically bred to be extremely short and round to develop a balloon-like appearance. 

Unfortunately, the saying “beauty comes with a price” couldn’t be any truer for these fish. I’ll touch more on this topic below while discussing the fish’s appearance. 

Read on! 

Balloon Belly Molly Appearance 

Although somewhat controversial and ‘artificial,’ balloon belly mollies are hands down the most beautiful molly types available. These fish get their name from their perpetually swollen and rounded belly that uncannily looks like a balloon. 

The tail and fins are quite short. The dorsal fin extends right along the fish’s back. The lyre-shaped caudal fin adds to their already brimming beauty. 

The face is slightly elongated and pointy. 

Balloon belly mollies are bred to have a sharp arch of the back, which has resulted in the unnatural curvature of the spine. While this feature does lend an alluring appearance, it also makes them prone to internal organ damage. 

Even worse, these fish are often subjected to artificial dying processes using needle injection to give them bright colors. 

Balloon Belly Molly Size 

Balloon belly mollies don’t grow too big. At max, they get around 3 inches (7.6 cm) long. 

Balloon Belly Molly Colors 

The most commonly available and hopefully natural color morphs of balloon belly mollies are black, white, and yellow. However, these days they’re found in a plethora of different colors like red, orange, silver, and even gold. 

Marbled and multicolored variants have also become quite common. 

But as I said above, these fish are often subjected to an artificial dying process to develop unique colors. And this cruel process often compromises their lifespan and potentially impairs them. So, choose what you’re getting wisely. 

Types Of Balloon Belly Molly 

Dalmatian balloon molly
Credits: Dennis Amith (Creative Commons license)

Different kinds of balloon belly mollies are available with different colors and fin shapes.

3 most commonly found balloon belly molly types are: 

  • Dalmatian balloon molly fish 
  • Red balloon molly fish 
  • Lyretail balloon molly fish 

Balloon Belly Molly Lifespan 

Balloon belly mollies can live for around 3-5 years with the right care and diet. However, since these fish are extremely vulnerable to different health conditions owing to their deformed shape, it’s not uncommon for them to die untimely. 

Years of inbreeding and intense production have made them genetically weak and prone to many diseases. 

The mortality rate is quite high. 

Balloon Belly Molly Temperament 

Like all mollies, balloon belly mollies are peaceful and amicable fish. They are not aggressive and will do exceedingly well in a community tank with other fish of similar temperament.

However, balloon belly mollies are fin nippers. Although peaceful and friendly for most parts, they have quite a reputation for being fin nippers. 

Males are especially known to nip the fins of other males to establish dominance or defend their territory. 

Balloon belly mollies are inquisitive fish that love to explore. And they’re shoaling fish that find safety in numbers. 

If the tank’s getting too crowded, these fish may show signs of aggression. 

Balloon Belly Molly Tank Mates 

Credit: Berlan Arlandis (Creative Commons license)

Owing to their pleasant personalities, balloon belly mollies make great members of any community tank. However, you should house them with other peaceful and friendly species. That’s because balloon belly mollies cannot really hold their own if put against a violent tankmate. 

The best tankmates for balloon belly mollies would be other balloon belly mollies. These are shoaling fish. So, they should at least be kept in a group of 4. 

Nonetheless, here’s a quick list of suitable balloon belly molly tankmates:

  • Guppies 
  • Platies 
  • Cherry barbs 
  • Dwarf gouramis 
  • Rosy barbs 
  • Tetras 
  • Zebra loaches 
  • Corydoras 
  • Swordtails 
  • Plecos 
  • Snails 
  • Shrimps 

You mustn’t house these fish with aggressive fish like green terrors, oscars, convict cichlids, and firemouth cichlids. 

There’s a good chance that your balloon belly cichlids will be bullied relentlessly – potentially to the point of death from stress or injury. 

Water Parameters For Balloon Belly Molly 

Temperature72-82°F (22.22-27.7°C)
General Hardness12-25 dGH (200-416 ppm)
Carbonate Hardness10-25 dKH (178-450 ppm)
Ammonia 0 PPM
Nitrite 0 PPM
Nitrate Below 20 ppm
Water FlowModerate
Swimming Region Middle

Tank Maintenance For Balloon Belly Molly 

Although small, balloon belly mollies have a big appetite and produce sizable bioloads daily. Therefore, you must stay on top of the water parameters always. 

Don’t skip water changes. There’s no one rule etched in stone on how much and how often to do a water change. It depends on your tank size and the stocking number. 

That being said, the rule of thumb is to perform a 30% water change once every week. This will help eliminate all the toxins brewing in the water, growth-inhibiting hormones, and dissolved solids. 

Since balloon belly mollies are more prone than others to contract health complications, you should pay special attention to maintaining their tank environment. 

Even the slightest inconvenience that would have no effect on other molly types could be fatal for balloon belly mollies. 

The tank’s ammonia and nitrite levels should always be maintained at 0 ppm. A spike in levels of these compounds will deteriorate the fish’s protective mucous layer and make it susceptible to pathogens waiting for their golden chance. 

We recommend using the API Freshwater Master Kit that monitors five different water parameters: pH, high pH, nitrite, nitrate, and ammonia. 

A liquid-based test like this one is far more accurate and reliable than test strips. 

Here’s a list of daily, weekly/biweekly, and monthly tasks you should perform to maintain the tank’s health:

Daily Tasks 

  • Check the filtration system 
  • Check the heater and temperature 
  • Do a headcount and observe fish 
  • Remove leftover food 
  • Top off the water level 

Weekly/Biweekly Tasks 

  • Wipe down the tank’s outer surfaces 
  • Scrape the inside glasses 
  • Shake off debris from plants and decors 
  • Siphon the substrate 
  • Monitor water parameters 
  • Conduct partial water change

Monthly Tasks 

  • Perform water tests 
  • Prune plants and deep clean decors as needed 
  • Perform weekly/biweekly tasks 
  • Change filter media 
  • Inspect tubing 
  • Fertilize plants if needed

Minimum Recommended Tank Size For Balloon Belly Molly

White balloon belly molly
Credit: Dennis Amith (Creative Commons license)

Mollies are often trumpeted as fish fit for small tanks, but this isn’t true. Even though balloon belly mollies barely grow any longer than 3 inches, they need a big tank owing to their activity level, the bioload they produce, and their fragile health. 

Therefore, the minimum recommended tank size for a pair of balloon belly mollies is 30 gallons. While some believe that it’s doable in a 20-gallon tank, too, I’d still recommend getting a bigger tank for the following reasons:

  • Small tanks are prone to get dirty a lot quicker 
  • Water parameters are more volatile in smaller tanks
  • Small tanks don’t have enough room for exercise and activities 
  • Small tanks have a higher concentration of growth-inhibiting hormones 
  • Small tanks lead to territorial disputes and profusely stress fish

Substrate And Decor For Balloon Belly Molly

A sandy substrate with a few decorative rocks and pebbles scattered across would be perfect for a balloon belly molly. I’d suggest using aragonite sand as it will disperse beneficial minerals into the water.

A few hardy aquatic plants can also provide refuge to your fish when stressed. 

Although balloon belly mollies typically swim in the middle region, a few decors placed strategically to create hiding places would be appreciated. 

If you’re planning to add plants, java fern, hornwort, anubias, and amazon sword can be some good options. But there’s one caveat. 

Balloon belly mollies require the addition of salt into the water as they age, which isn’t good for the plants. So, it may be a bit challenging to create an environment conducive to both mollies and plants. 

Also, make sure that you don’t use driftwood as it will make the water acidic. 

Recommended Equipment For Balloon Belly Molly 

Since balloon belly mollies have a ‘bigger’ Achilles’ heel than other molly types, it’s only fitting to provide them with the most reliable equipment that offers the best care. 

That’s why we have meticulously researched and handpicked the following equipment for your balloon belly molly. Have a look! 

Penn-Plax Cascade Canister Filter 

What We Love: 

  • Affordable 
  • Works at 185 GPH
  • Large capacity media baskets 
  • Flow valves that rotate 360-degrees for easy maneuvering 


  • Can be loud 
  • Can be hard to reach customer service 

Hygger Titanium Aquarium Heater 

What We Love: 

  • Fully automatic control 
  • Temperature range from 32-104 degrees F
  • Digital LED display


  • Heating element can fall off the glass

Fluval Multi-Chamber Holding And Breeding Box

What We Love:

  • Space-saving design 
  • Good water circulation
  • Great to raise fry and acclimatization 


  • Small fry can be flushed out through the gap
  • Unclear instructions 

Balloon Belly Molly Diet 

Balloon mollies are omnivores. Therefore, they can enjoy a wide variety of food, including meat. However, they strongly lean towards a plant-based diet as it suits their physical requirements and taste palate. 

Since these fish aren’t found in the wild, we wouldn’t know what their natural diet would include. However, their wild cousins mainly snack on aquatic insects, algae, rotifers, plants, and crustaceans in the wild. 

We recommend zeroing in on a healthy, good-quality flake food or pellet or multiple and alternating between them for a staple diet. Then, you can occasionally reinforce their diet with the following:

  • Algae 
  • Spirulina tablets 
  • Boiled veggies like carrots, peas, zucchini, and cauliflower
  • Freeze-dried bloodworms and crickets 
  • Brine shrimp 
  • Boiled and shredded chicken breast 
  • Aquatic plants 

Since these fish have a compact body, their digestive tracts are malformed. Thus, they are very prone to conditions like bloating and constipation, which, if not treated on time, can even cause death. 

So, we recommend not to experiment too much with their diet. It’s better to play safe. Don’t give any food the benefit of the doubt if you have reservations about it. 

If the fish is bloated or constipated, feeding cooked and skinned peas can be helpful as they’re rich in fiber and ease digestion. 

Give two meals a day and remove uneaten food promptly, so the water isn’t polluted. 

Balloon Belly Molly Breeding 

Breeding balloon mollies is surprisingly easy. In fact, they can quickly overpopulate your tank in just a few months. You can slightly increase the water temperature, feed a protein-rich diet, and perform a water change if you want to encourage breeding. These should do the trick. 

Watch this fascinating video of a majestic balloon belly molly giving birth to 53 babies!

Balloon Belly Molly Male VS Female 

Male balloon belly mollies have an altered anal fin called a gonopodium. It’s pointy and thin. On the contrary, a female’s anal fins are triangular, short, and fan-like. 

Females also have a pregnancy spot that will help tell them apart from males quickly. 

Balloon Belly Molly Male To Female Ratio 

Balloon belly mollies should be kept in a ratio of 1 male for every 2-3 females since males can be pretty vigorous in their pursuit of mates. 

This ratio will help spread out the unduly aggression and harassment the females inevitably face. 

When Do Balloon Belly Mollies Sexually Mature? 

Balloon belly mollies sexually mature by the age of 4-5 months. If you are not keen about raising their fry, you need to separate males and females before they come of age. 

Balloon Belly Molly Spawning 

Balloon belly mollies are livebearers that give birth to anywhere between 40-100 fry. And they can give birth as frequently as once every 30-45 days. Quite prolific breeders, aren’t they? 

However, the number of fry they produce depends on factors like age, size, experience level, environment, and stress factors. Usually, older and bigger females give birth to more fry than small, inexperienced ones. 

The breeding tank should at least have a 25-gallon capacity. In addition, it should have excellent filtration, as well as good lighting to encourage algae growth. 

Balloon belly mollies don’t form monogamous pairs. Males will try to fertilize any female that crosses their path. He will flare his fins, do a little shimmy, and may even resort to nipping to coax the female into mating. 

Naturally, the largest and strongest males have a better chance of mating. 

The consenting female will allow the male to fertilize her eggs. Then, the male will release milt, a fluid containing sperm, into the female’s opening. 

How Long Are Balloon Belly Mollies Pregnant For? 

Balloon belly mollies are pregnant for anywhere between 40-70 days. The duration of the gestation period is influenced by factors like age, health, size, and environment. 

How To Know If Balloon Belly Molly Is Pregnant? 

The following five signs can help you determine if your balloon belly molly is pregnant:

  • Swollen and distended belly 
  • Increased appetite 
  • Prominent gravid spot 
  • Aggressive and aloof behavior 
  • A strong bulge below the gills

Do Balloon Belly Mollies Eat Their Babies?

Yes, balloon belly mollies eat their babies. Therefore, you need to separate the mother from her younglings as soon as they’re born. 

These are the 3 possible reasons why balloon belly mollies perform infanticide:

  • The spill-over response triggered by stress 
  • Weeding out weaklings 
  • An effort to replenish fat storage

How To Care For Balloon Belly Molly Fry? 

Ideally, you should set up a fully-cycled tank for your fry. However, if that’s not possible, a breeding box would work too. 

The tank shouldn’t be too big, to begin with. The fry will find it hard to find food in a big tank. So, a 10-gallon tank would work perfectly. 

Maintain a stable temperature somewhere around 72-82°F (22.22-27.7°C) and ensure proper aeration using an air pump. 

Opt for a sponge filter for filtration, so it doesn’t suck in little fry. 

Leave the tank bare without any substrate or decor. These things will only make it hard for your fry to find their food. 

And lastly, perform water changes routinely to ensure no harmful compounds are brewing inside. 

What To Feed Balloon Belly Molly Fry?

When born, balloon belly mollies are barely ¼” long. So you can imagine how tiny their mouths are. You can give them microworms, baby brine shrimp, daphnia, pulverized flakes, and a paste made of egg yolk. 

Balloon Belly Molly Diseases 

Mollies are generally hardy and have a pretty strong immune system. However, balloon belly mollies are plagued with genetic deformities that put them at several health risks. 


The compressed digestive tracts mean balloon belly mollies are more prone to constipation than usual. Therefore, it’s crucial to incorporate fiber-rich food into their diet. 

You can incorporate protein-rich food like skinned peas, blanched curly lettuce, cucumber, and spinach in their diet. 

And to treat constipation, you need to feed high-fiber foods that will act as laxatives. So while treating, don’t give the fish any other food – especially pellets, flakes, and frozen items. 

Cooked and skinned peas are the most commonly used laxative for aquarium fish. 

You can also use epsom salt that works as a mild muscle relaxant to treat moderate to severe constipation. 


Shimmying is quite common in livebearers like mollies, characterized by violent rocking of the body from side to side in a snake-like slithering motion. 

In fact, this disease is so common among mollies that it’s also known as Molly Disease. 

The 3 most common reasons behind shimmying are:

  • Low water temperature forces fish to shimmy to get warmer 
  • Low pH levels is burning the fish’s skin from acidic water 
  • Low mineral levels that’s shutting down the fish’s internal organs 

If you find your balloon belly molly shimmying, you need to finetune its living environment by maintaining a pH between 7.0-8.0, a temperature between 76-82°F, and increasing the water’s mineral content. 

You can use supplements like crushed coral, Seachem Equilibrium, and Wonder Shell to enhance the mineral content. 


Ich on balloon belly mollies can be harmless or fatal depending on when you detect it and how you treat it. It is caused by a ciliate protozoan and manifests as tiny white dots dotted across the body. 

The following are the main symptoms of ich in mollies:

  • Small, white dots like salt grains across the body 
  • Flashing 
  • Loss of scales 
  • Rubbing body against different surfaces 
  • Loss of appetite 
  • Listlessness 
  • Panting 
  • Bruising 

An ich outbreak occurs in a fish tank mainly due to these 3 reasons:

  • You forgot to quarantine the new fish 
  • Your mollies are stressed and have a weakened immunity 
  • Your tank is dirty

We successfully use Aquarium Solutions by Ich-X to treat ich. If you want to know more about how we use it, head over here

Final Words: Balloon Belly Molly Care Guide 

I personally wouldn’t get balloon belly mollies for the same reason I wouldn’t get jellybean cichlids. But no judgment if you’ve brought one home! I’m only here to help you give your fish the best life possible. 

It’s vital to know that balloon belly mollies aren’t as hardy and strong as your regular mollies. These fish have a compressed body and a deformed spine that make them susceptible to different health woes. 

On top of that, they’re often injected with artificial dye to produce the bright red, orange silver colors that we see so often these days. 

Therefore, these fish have a high mortality rate – they often die untimely. 

Just make sure you provide a clean, stress-free environment and feed a healthy diet every day. And your balloon belly molly might just make it past its fifth birthday. 

Good luck! 

Recommended Readings!

How Long Do Mollies Live? Extend Their Lifespan!

How Long Are Molly Fish Pregnant For? Twice As Long As Guppies!

What Do Molly Fish Eggs Look Like? Little Yellow Balls!