How Many Mollies Can Fit in a 10 Gallon Tank?




how many mollies in a 10 gallon tank

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When you are new to the world of keeping fish as pets, starting off with a small tank is always a good idea. Of course, the downside to having a smaller tank is that you have less room for fish. So, how many mollies can live in a 10-gallon aquarium?

The answer to this question depends on how large your mollies are. For example, if you have 3-inch mollies, you can probably only keep 2 or 3 in a 10-gallon tank.

In this article, I will give guidelines on how many mollies you can keep in a 10-gallon tank, depending on the molly fish size.

How Many Molly Fish Can Survive in a 10-Gallon Tank?

The number of mollies that can survive in a 10-gallon tank really depends on the size of your mollies. As a general rule of thumb, you can expect to keep about 1 inch of fish per gallon of water.

So, if you have 3-inch mollies, you can probably only keep 3 of them in a 10-gallon tank. If you have only a couple of inches of mollies, you can probably keep 4 of them in a 10-gallon tank.

However, I don’t recommend housing these active guys in such a small space since they need at least a 20-gallon tank. Also, mollies are shoaling fish that need to be in groups of six fish or more in a larger tank.

Further, there are several controversies surrounding the ‘one inch per gallon rule.’ First, it doesn’t take into account decoration or substrate volume. Second, it entirely ignores a fish’s height.

That being said, most experts agree that you can only apply this rule to slender-bodied fish smaller than 3-4 inches in length.

How Many Male & Female Mollies Can I Keep in a 10-Gallon Aquarium?

If you’re a beginner, start with one male and two females to get started. You will have a colony of mollies in no time!

In addition, having two females for one male will help distribute the attention and resultant bullies more evenly. This way, they will at least have some time to rest and feed properly, especially during the mating season. 

Also, don’t forget to add bushy floating plants to your 10-gallon tank. This will help to create some hiding spots for your ladies and give the male molly a place to rest when he’s not busy chasing his ladies around. Besides, they will create places to hide for baby mollies when they are born.

How Many Black Molly Fish Can I House in a 10-Gallon Tank Size?

Blackfin mollies generally grow to be around 3-6 inches. If you have a 5-inch black molly, you can comfortably keep two of them in a 10-gallon tank.

However, if your black molly is 6 inches, then you should only keep one in a 10-gallon tank. Remember, the bigger your mollies are, the fewer of them you can keep in a smaller aquarium.

How Many Sailfin Molly Fish To Keep in a 10-Gallon Tank?

Sailfin mollies are relatively small fish, seldom growing over 5 inches long. As a result, you can keep 2 mollies in a 10-gallon tank without overcrowding the space.

In addition, sailfin mollies are livebearers. This means they will give birth to live young (usually around 10-60 babies at a time). So, if you don’t want your tank overrun with baby mollies, you can keep two female sailfin mollies. 

You can also opt for a breeder tank where the females can breed. 

How Many Dalmatian Molly Fish To House in a 10-Gallon Tank?

In captivity, Dalmatian mollies rarely exceed 4.75 inches in length. Therefore, you could keep 2 Dalmatian mollies in a 10-gallon tank.

However, these guys are sociable and engaged and enjoy being in their own company. Thus, I don’t recommend keeping them confined in such a tiny area.

How Many Lyretail Molly Fish Can Live in a 10-Gallon Tank?

A typical female molly grows to be up to 5 inches long. Therefore, you can only keep two of them in a 10-gallon tank.

Males are significantly shorter, measuring only three inches long. So you can technically house three of them in a 10-gallon tank. However, putting males in such a tiny tank is a bad idea- they will literally fight to the death.

How Many Gold Doubloon Molly Fish Can Survive in a 10-Gallon Tank?

Gold doubloon mollies can grow up to 5 inches long. So you can add two of these fish to a 10-gallon tank.

However, gold doubloon mollies practically need at least 25-gallon tanks. This is due to the fact that they are very active swimmers that need a lot of space to roam around.

Additionally, they need plenty of vegetation and hiding spots in their tanks. Otherwise, they will become stressed and may contract diseases. 

Why Should I Avoid Housing Molly Fish in a 10-Gal Tank?

how many mollies in a 10 gallon tank

They Will Feel Lonely

Mollies are sociable fish that love being in the company of their own kind. In the wild, they live in shoals of 6 or more fish. So they are not used to being alone. They, therefore, need tank mates. 

As a result, keeping your fish in a 10-gallon tank alone will make them feel like they are in solitary confinement! 

They Will Not Have Enough Swimming Space

These species of fish are very active fish that love to swim around. In the wild, they live in rivers and streams with plenty of space to move around.

However, in a small tank, they will constantly bump into the glass or each other. Thus, their tank will be cramped and stressful, and their health will suffer.

They Will Not Have Enough Hiding Spots

Hiding space is the fish equivalent of a ‘safe space.’ Mollies need hiding spots to feel safe and secure in their ideal environment.

In a 10-gallon tank, you won’t be able to add any form of decoration or vegetation. As a result, these slim-bodied fish will constantly be on edge, and their stress levels will be through the roof!

Their Growth Will Be Stunted

If you’re keeping baby mollies in a 10-gallon tank, they will eventually outgrow it. Once you have full-grown molly fish, they will be too big for the tank, and their bodies will be cramped.

This will stunt the fish’s growth, leaving them small and malformed for the rest of their lives. How can anyone be so cruel to such cute creatures?

Last Words

Mollies are beautiful, inquisitive fish that make great additions to any aquarium. However, they need plenty of space to swim around and plenty of hiding spots to feel safe.

Community tanks can support a high water column and, consequently, a larger number of mollies. The minimum tank size should depend on the size of the mollies. 

However, you can keep two mollies in a 10-gallon tank if you provide them with the proper care and attention. The types of filtration you use depend on water quality. For instance, alkaline water may require higher filtration.  

A water testing kit can help test the level of nutrients in the water. Coastal water has higher nutrient levels compared to city water or bottled water. Cleaner water, on the other hand, has little nutrients. 

I hope this article helped you learn everything you need about these ornamental fish in a 10-gallon tank. If you have any questions, feel free to leave them in the comments below.

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