Can Glofish Live With Mollies?

It seems you want a really attractive tank if you want GloFish and Mollies together. 

There is a possibility that Glofish can live with Mollies amicably!  Let us show you how.

How To Know If Fish Are Compatible?

Although there are no rules set in stone, there are general guidelines you can follow to know if fish are compatible with one another.

Guidelines to tank mate compatibility:

  • Should have the same water parameters
  • Fish should have roughly the same size and temperament
  • Tank size should be large enough to house both species of fish
  • Shy or aggressive schooling fish should be kept in groups
  • The tank should have lots of plants (live or otherwise) and decorations for your fish to hide in
  • Don’t mix aggressive fish in the same level of the water column
  • Don’t introduce smaller fish to aggressive fish
  • Be prepared to separate some fish if it gets rowdy

You can never mix freshwater and saltwater fish in one tank.  But there are brackish water-dwelling fish that can be acclimated to either saltwater or freshwater.  We’ll discuss this more later.

When it comes to tank size, there is no concrete formula you can follow because size isn’t the only factor.  It also relies on how territorial a fish is.  That’s why you always hear the phrase “bigger is always better” when it comes to aquarium sizes.

Even the dimensions of your tank would depend on the personality of each fish.  Active fish would need wider tanks (as opposed to taller or narrower ones) so they can swim to their hearts’ delight.

When it comes to temperament, there will always be exceptions, as proven by hobbyists who have kept odd combinations of territorial or aggressive fish together.  This is because each fish has its own personality, and you’ll never know unless you try.

Most fish, even the peaceful ones, are opportunistic.  They eat what can fit in their mouths.  That includes smaller fish, fry, and eggs.

Tip: Juveniles of what normally wouldn’t go together become the exception to these rules.  When different fish are introduced early on in life, they accept one another in the long term.

Can Glofish Live With Mollies
Can Glofish Live With Mollies

Let’s get to know Molly Fish more to determine their likes and requirements.

How Many Gallons Does A Molly Need?

Molly Fish are really fast swimmers, so they will need a lot of space to live in.

A 20-gallon aquarium should be the bare minimum for a group of 4 to 6 Mollies.  If you’re considering tank mates, a 55-gallon should suffice.

Why?  Because female Mollies grow up to 3 ½ inches in length, while males reach about 3 inches.  Larger Mollies (sailfins) grow up to about 5 or 6 inches long. 

Let’s examine their preferred living conditions.

What Do Mollies Like In Their Tank?

You may notice that Mollies, like other livebearers, enjoy a bit of a higher pH and hardness than what’s common in tropical freshwater fish. 

Glofish With Mollies
Glofish in Mollies Tank

Their required water conditions are:

Water ParametersRange
Temperature72 to 78 deg F
pH Level7.5 to 8.2
Ammonia0 ppm
Nitrates0 ppm
Nitrites< 40 ppm
Water hardness15 to 30 GdH

Mollies produce a lot of waste.  Highly active fish equals highly active eaters equals highly active poopers.  If you’re keeping Mollies with anything, make sure you have a good filter.  They even graze on the algae in your tank.

And because these omnivores like algae, you have to have live plants in your Molly tank.

The parameters above might be confusing for those convinced that Mollies are brackish-water fish.  Let us explain.

Do Mollies Need Brackish Water?

Mollies that were raised overseas prefer brackish water because their breeders mix seawater with freshwater to reduce costs. 

It might be good to ask your pet store whether the Mollies were imported or raised locally.  If you have the brackish variety, add a tablespoon of aquarium salt for for every 3 gallons of water in your tank.  Mollies are tolerant of some salt and might need some at first to avoid the shock of total freshwater.

If you have Mollies that were completely raised in freshwater, salt is not necessary unless you’re treating them for a condition such as ick.

Important: If you’re getting Mollies as GloFish tank mates, make sure they’re the locally-raised, freshwater variety.  The level of salinity will complicate caring for the fish, which might kill one variety or the other.

Tip: If for some reason you already have Mollies that prefer brackish water, it would be wise to use crushed coral as substrate to provide a buffer to your pH level.  If your area has very soft water, you should add minerals such as calcium and magnesium. 

If you can’t find freshwater Mollies, a good idea would be to breed them yourself.  Take the Molly babies that were born in your tank and do frequent water changes to get rid of the salt.  Do this for several weeks and you’ve got yourself freshwater Mollies!

Now that you have freshwater Mollies, are they ready to be good neighbors to GloFish?

Is Molly Fish Friendly?

There are 39 currently known species of Mollies, most of which are hardy and peaceful.  They are often mistaken as schooling fish because they are livelier in groups, but Mollies do not get aggressive in small numbers as schooling fish do.

There are two main varieties of Molly fish: shortfin and sailfin.  Sailfin Mollies are larger than shortfins and have fancy dorsal fins.  They’re also more aggressive, so stick with the shortfin Mollies if you’re keeping them with GloFish.

Molly FIsh
Molly Crescent FIsh

Like all livebearers, they’re prolific breeders.  Male Mollies like to establish dominance in the tank, keep a 2 or 3 females for every male you have.

Any kind of Molly Fish, however, might show acts of aggression such as nipping if kept in an overstocked tank.  So it’s advisable to have the right-sized aquarium for them and their tank mates.

Can GloFish Live With Mollies?

If you’re looking for GloFish tank mates, Mollies may or may not be what you’re searching for.

There are currently 5 varieties of GloFish: Tetras, Danios, Bettas, Barbs, and Sharks.  All of these have their unique temperaments and some are schooling fish.  So compatibility with Mollies depends on the variety of GloFish.

The rule that applies to this case is if Mollies can live with the non-GloFish version, then they can do so for that GloFish.

Can Mollies Be Kept With Tetras?

Live-bearing fish like Mollies are good tank mates for the GloFish Tetra. 

All kinds of Tetras can live peacefully with Mollies including the GloFish Tetra, which is the glow-in-the-dark version of the Black Skirt Tetra.  GloFish Tetras should be in a school of 6 or more.

GloFish Tetras and Mollies have the same laid-back temperament and the same water parameters.

Next up: GloFish Danios.

Can I Keep Zebra Danios With Mollies?

GloFish Danios are glow-in-the-dark Zebra Danios and will respond to Mollies the same way.

Mollies and GloFish Danios would live amicably as long as the GloFish have their own school.  Again, keep at least 6 GloFish Danios in the tank.

But what about the other schooling GloFish variety, Barbs?

Can Mollies Live With Tiger Barbs?

Keeping Mollies with GloFish Barbs is a risk and not recommended, but it is possible.  Short-finned Mollies may be able to tolerate Barbs.

Needless to say, they’re not for the beginner.  If you have relative experience and want this combination to work, you have to make sure the Barbs are in their schools.  The more fish in the group, the more peaceful they are.

A planted 55-gallon for a school of GloFish Barbs and a group of short-finned Mollies is wide enough space for them.  If fights do break out, move bullies to another tank.

If Mollies with GloFish Barbs are risky, what about having the more aggressive GloFish Shark?

Can Rainbow Sharks Live With Mollies?

This combination is even harder.

Most hobbyists who have tried keeping GloFish Sharks with Mollies end up with dead Mollies.  Even if they don’t usually occupy the same part of the water column (GloFish Sharks are bottom dwellers and Mollies like the middle), we do not recommend it.

Some have reported a peaceful start to the relationship.  But then the GloFish Shark would chase the Mollies.  Even with intervention, the latter would be found dead.

Sharks are bottom dwellers but they do get to about 6 inches long EACH.  They’re very active fish and are aggressive towards other fish that approach their territory. 

Sharks choose their tank mates.  They’ll end up bullying if they don’t want a certain fish living in the same tank as them—Mollies included!

Okay, so Sharks are a no.  But is it the same for the equally aggressive but much smaller Betta fish?

Can Mollies And Betta Live Together?

Female GloFish Bettas can tolerate the presence of Mollies, but a male Betta might not. 

We already know that male GloFish Bettas are more aggressive than females, so better avoid those. 

Female GloFish Bettas, though, are a little different.  They’re more dominant than the Mollies, and you might notice them flaring their fins for a few days when introduced to new tank mates.  That’s pretty normal.

But if the aggression is constant, then separate the fish.  Trouble is brewing.


Not all GloFish varieties are compatible with Molly Fish.  Those that don’t can be kept better among themselves.

But with those that do, expect a very colorful, enjoyable community tank.

Recent Posts