How Many Mollies Should Be Kept Together?
Has your molly been under a lot of stress lately? Is your molly not behaving the way it should? If this is the case, there’s a potential you’ve overrun your tank, which might explain your molly fish’s unusual behavior.
The best approach to keep mollies in your tank is to introduce them in proportion to the ratio. It is best to have 3 female and 1 male molly fish so you can keep 4 mollies in a single aquarium.
It takes as much attention as it appears to be little and fragile. Overcrowding can occur not just when you have a large number of fish in your tank, but can also occur if you have added too many decorative things to your tank. They take up a lot more room, making it difficult for the fish to move around in the tank.
So read on for more information on mollies and their preferences.
A Little Background Information on Molly Fish
You have undoubtedly encountered molly fish (Poecilia sphenops) at some time in your life. One of the most common freshwater species sold in aquariums is mollies. They’re the ideal species for novices and are sometimes available for a few dollars each. Many seasoned aquarists also like them, though. The molly, which is calm by nature, is excellent for communal freshwater aquariums. They are simple to maintain and adapt well to the majority of common tank configurations. Mollies may be found in the wild all throughout North and South America. They frequently live in sluggish tropical rivers that are filled with flora. Mollies have undergone a lot of cross-breeding since they were first used in fishkeeping. There are many different kinds and hues available as a consequence.

Mollies’ Tank Size
Even though Mollies look to be kept simple, you must satisfy specific tank demands to keep your small puppies healthy and pleased. These tiny invertebrates eat flavorless food. They eat leftovers, flakes, live, frozen, and edible items including brine shrimp, daphnia, and blood worms. It would be advantageous if you were very careful about how many Mollies you maintained in the specified tank size and did not cram the tank. Overcrowding your tank with mollies is NOT, I REPEAT, NOT acceptable. It can lead to conflicts amongst the breeds themselves.

A gallon of water is needed to grow one inch of molly. You must select the size of your tank based on the size of the species. 10 gallons of water will be plenty for four of the mollies. However, if you have Sailfin mollies, you’ll need roughly 30 gallons of water for four of them [size may vary]. For them, tall aquariums are advised.
How Many Molly Fish Can You Fit in a 5-Gallon Tank?
Space occupied by the ornamental must also be taken into account since it is explicitly advised to minimize congestion and construct the landscape utilizing substrates, living plants, rocks, and caverns. This means that keeping only one Molly in a 5-gallon aquarium is a prudent choice on your part. However, based on my expertise and experience, I advise you not to leave your molly unattended.
How Many Molly Fish Can You Fit in a 10-Gallon Tank?
The number of mollies you can retain grows as your tank size expands. Sounds intriguing? It is, but you are not free to add as many as you like. There must be a cap on the population. A maximum of 3 Mollies can be added to a 10-gallon aquarium.

Consider a molly to be 3 inches long; it will require 3 gallons of water. As a result, assuming their usual size is 3 inches, 3 x 3 is 9 gallons of water for 3 Mollies, with 1 gallon left over for the accessories that take up tank space. We can see that depending on size, different amounts of Mollies may be put in the 10-gallon. This is only because fish need more space to swim freely.
How Many Mollies Can I Put in a 20-Gallon Aquarium?
20/3 is equivalent to 6.67 in a 20-gallon tank. As you can see, you can add up to 6, or 3 inches of mollies in your tank. In a 20-gallon aquarium, if the molly fish is 4 inches long, you can add 20/4 = 5 mollies. However, adding 5 fish is a hassle, so it’s best to stick to 4 Molly. If the molly is 2 inches long, you can add 9 mollies. However, not all Molly are the same size.

How Many Molly Fish Can You Fit in a 30-Gallon Tank?
In a 30-gallon tank, you can add up to 30/3=10 Mollies by doing a similar calculation. A 30-gallon aquarium is necessary if you choose a Sailfin Molly, though, since they demand a lot of areas to swim.

I think you’ve noticed that I’ve been recommending that you keep the Mollies at even numbers. It is preferable to maintain them in pairs, with an equal number of Mollies of each gender. Or, to lessen the likelihood of bullying, adhere to the general rule of “two ladies per guy.”
How Many Molly Fish Can Your Aquarium Hold?
The maximum number of Mollies your tank can hold varies on its size. So, for your convenience, you can figure out how many Mollies you can maintain in your tank on your own.
The formula is “Size of the tank Max Length of a Molly Fish = Number of Mollies” to determine this.

In this, the tank’s size is the first decision we make. Then, we add the desired number of Molly fish or assume a certain amount. Take two women for every man, or an equal number of men and women. Please measure each one’s length after that since it is simpler to round off the decimals. The length of each fish should then be added. Next, divide the tank’s volume by the whole length. The tank’s capacity should then be subtracted from the result. You may retain Mollies of any length in your aquarium with this information.
An illustration
If your tank holds 50 gallons and the balloon molly can grow to a maximum size of 2 inches, we can now estimate how many mollies are present there:
Mollies: 50/2 = 20
This means that a 20-gallon tank can hold Mollies that are up to 19 inches long (round off). we can add three female Mollies or two male Mollies. Mollies will end up being 18 inches long (3*4+2*3) as a consequence.
Best Fish to Keep in a Tank with Moles
Remember to think about the tank mates you may add with mollies. Mollies are calm fish that get along well with other friendly communal fish, as was previously said. Other mollies, Guppies, Tetras, Swordtails, Platies, Danios, Gouramis, and female betta fish are a few fish tank companions that get along well with mollies.
Typical Molly Types
According to estimates, there are about 39 distinct species. Just a handful of the most well-known ones are included here. You’ll probably need to do some research if you’re looking for anything that’s a little less well-known (since they might not be at your local fish store).
Black Molly
These mollies are all black, as you could have guessed! The fins may have a few spots of yellow or orange, but the majority of the body is completely black.

Mollies Sailfin
The body type of the sailfin molly is typical. The dorsal fin, on the other hand, is significantly higher and extends to the tailfin. Sailfin variations come in a variety of hues (including black).

Balloon Molly
Balloon mollies get their name from their belly, which is fitting. The tummy develops a round, bulbous form even when not pregnant. Similar to sailfin, balloon mollies come in a variety of hues.

Lizard tail Mollies
The tailfin of the lyretail molly is exquisite. Like other mollies, it has a fanned form. The top and bottom, however, contain long rays that give them a forked look.

Dalmation Mollies
The Dalmation molly, which is quite common in fish markets, has a base color of white. The body is covered with black flecks, giving it the appearance of a Dalmatian dog. Standard, lyretail, balloon, and sailfin dalmatian mollies are also available.

Gold Doubloon Molly
Another species that is widely bought is the gold doubloon molly. Its body is bright yellow in the front and completely black in the back.

How Do You Raise Mollies? How To Breed Mollies?
Mollies are some of the fish that are simplest to breed in captivity and will often mate frequently.
Because they are livebearers, the fish releases live fry as the eggs develop inside of them. Clean water and other ideal circumstances are required to promote breeding. The temperature must be raised just enough to cause mating, but not over 78 degrees Fahrenheit. When they are ready to mate, ladies allow males to fertilize their eggs while males put on a courting show for females. The biggest men are preferred by females while mating. After fertilization, females release the fry 35 to 45 days later, and bigger females can discharge up to 100 youngsters.
Regardless of gender, adult mollies are known for eating their young. Therefore, it’s crucial to distinguish the fry from them. Pregnant mollies can be kept in a breeder’s box until they give birth as one tactic. The box has openings so that children can escape while keeping adults within.
The Lifespan of Molly Fish
The lifetime of a molly fish is typically 3 to 5 years. Even if they aren’t the longest-living freshwater species, depending on the kind you acquire, there may be some wiggle space. Their longevity will be considerably impacted by the level of care you give. Mollies are resilient, but they are also susceptible to illnesses brought on by an unclean habitat.
Normal Size
A fully developed molly typically measures between four and four and a half inches. They can be kept in aquariums that aren’t too big because of their reasonable length. There are even greater kinds of sailfin. They frequently grow to be closer to five or six inches in length.
Care for Molly Fish
Practically everyone can take care of a molly fish. They are an excellent choice for anybody looking to start fishkeeping because they don’t need a lot of care to stay healthy. Your mollies should thrive as long as you adhere to the standard care recommendations shown below!
Tank Size
Mollies thrive in tiny and medium-sized aquariums because of their little size. The majority of molly fish may thrive in tanks as little as 10 gallons. Although a larger tank is always preferred if you have additional room, that tank size guideline is enough for up to four mollies. You must increase the tank capacity for a larger group by at least three gallons of volume per fish.
Water-related Parameters
In the wild, mollies may be found in a variety of settings. This freshwater fish has a wide native range. They may short swim in brackish or even open ocean waters, despite the fact that rivers are where they are most usually spotted!

Mollies are quite adaptive as a whole. Hard water, neutral pH, and warm water are favorites. Contrary to popular perception, you don’t need salt in the water to maintain the health of these fish. They are quite content to spend their entire lives in areas with just fresh water. Here are some solid baselines that will work for the majority of mollies, however exact water conditions may vary depending on the species you obtain.
- 72° to 78° Fahrenheit for the water (some species as high as 80 degrees)
- 7.5 to 8.5 on the pH scale
- 20–30 KH for water hardness
We advise every aquarist to get a dependable (and precise) water test kit. When it comes to quickly assessing the condition of your tank and making modifications as needed, this will be your lifeline.
How To Fill Their Tank?
Mollies thrive in environments with natural accents that resemble the tropical rivers they naturally inhabit. This calls for increasing the number of plants and shelter options. Add sand or gravel substrate to the bottom of your aquarium. The middle and higher portions of the water column are where mollies spend the majority of their time. They won’t linger down by the substrate for very long.

Add some live plants to the substrate as an anchor (mollies use these plants for shelter). It’s a good idea to have both taller plants like Anubias and shorter kinds like Java fern. Arrange the plants around the outside of the aquarium so that there is still a free-swimming room.
Finally, add some rocks, caverns, and driftwood to the décor. Those goods will give some extra protection. Furthermore, they may produce algae for your mollies to consume.
Filtration & Lighting
Standard illumination is adequate. Mollies aren’t fussy about illumination, but it is necessary to maintain the plants healthy.
Because mollies create a lot of trash, you’ll need a good filtering system. A small group of people can readily boost ammonia and nitrate levels to dangerous levels. Select a strong filter that can hold a large amount of bio media. Additional internal or exterior sponge filters are also beneficial.
Common Potential Diseases
Mollies, like any other fish, can get sick. There are a few distinct sicknesses to be aware of. Molly’s illness and constipation are two examples.
Molly’s sickness, often known as the “shimmies,” should be avoided. It happens when the water’s parameters are unstable. Many aquarists discover the condition when temperatures rise or ammonia levels rise. The sickness causes the molly fish to be unable to swim normally. Instead, they “shimmy” and wiggle in a single spot. The good news is that most fish recover fast once the circumstances are corrected.

Constipation is a problem for balloon mollies. The physical morphology of this fish results in compressed organs. Eating too much or too rapidly might result in potentially dangerous constipation, so keep an eye on their eating habits. Mollies may contract common freshwater illnesses in addition to these two issues. Infections such as ich, bacterial infections, flukes, and parasites are all possible.
Nutrition and Diet of Molly Fish
Molly fish eat largely plant-based meals. While they are not known to be voracious algae eaters, they do like it on a regular basis. They may be seen using their jaws to scrape off rocks, wood, and glass. These fish consume blanched vegetables such as lettuce, spinach, and zucchini in addition to algae.

A high-protein snack every now and then is also appreciated. Mollies will consume both live and frozen blood worms, daphnia, and brine shrimp. In addition to nutritional benefits, live meals provide much-needed excitement at feeding time. It’s a good idea to include it in your fish’s diet sometimes. Another good feeding option to look into is dry commercial flakes and pellets. Look for nutritionally balanced foods.
Temperament and Behaviour
Mollies are generally laid-back fish. They are calm and get along well with others. Mollies are shoaling fish, therefore they require the company of others to feel at ease. At the absolute least, you should keep a group of four fish. If possible, a larger group is preferable!
These fish will form groups to explore the aquarium and swim as one entity. They’ll then go their own ways.
The Bottom Line on How Many Mollies Should Be Kept Together?
Mollies are great pet animals in my opinion. A little care for the number of Mollies you pet in your tank may provide you with the joy of watching these gorgeous babies develop.
Overcrowding is an absolute no-no. I hope this post has helped you decide whether or not to introduce Mollies to your tank. Regardless of tank size, adding Mollies to a larger tank should not be done carelessly. It might be dangerous not only for them but also for the rest of your fish.
Mollies require space to swim freely and stay healthy. I’ve enjoyed being a Molly keeper since it’s so simple to feed and care for them. They are little and lovely. Furthermore, their placid demeanor makes it easy for them to be mixed in with other tank mates.
If you wish to add Mollies to your collection and learn more about them, follow the link to our Mollies article.