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Can Guppies Live Together With Mollies in the Same Aquarium?

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The first fish I got many years ago were guppies. When I saw how beautiful mollies were, I wanted to get them as well! But I did not know yet if it both fish could get along, but since I have learned.

Can guppies and mollies live together in the same aquarium? Yes, most definitely! Both fish are considered “community fish” and require the same water parameters. As long as there is enough space for all the fish you are good to go.

While both fish are known as peaceful community fish, there are a lot of thing that you might not have thought about up until now. For example, these fish are so similar they might compete for the same food. I will make sure you know everything you need to know at the end of this article.

Similar needs

Both guppies and mollies share the genus called Poecilia. They are very similar fish, and they have similar habits like eating at the surface or open water. They are both livebearers and the male and female fish are easy to distinguish.

Both fish require tropical aquarium temperatures of between 74 and 82 degrees Fahrenheit (24 to 28 °C). They also both require clean water just like any other fish. These fish species are quite hardy, but do not tolerate any measurable ammonia and nitrite dissolved in the water.

Both fish have a very similar diet. This might become a problem as this means that they are competing for the same food.

Possible competition

Because these fish are so similar, they are regularly competing for food and territory. While they are both considered to be peaceful community fish, you need to check if they are getting along during feeding.

It might happen that one of the species will dominate, so you have to make sure all fish in the aquarium get enough food to eat.

Also, you have to make sure that there are plenty of hiding spaces throughout the aquarium, and the tanks needs to be big enough. If there is little room and you are not providing your fish with enough food they will definitely start competing.

Potential cross breeding between guppies and mollies

Mollies and guppies are both livebearers, and because they are so similar it might happen that they crossbreed. While most baby fish do not make it to adulthood, it does happen sometimes. These adult fish are not fertile and will not reproduce.

Sadly, most babies from the guppies and mollies will die before, during or shortly after they are born.

Both guppies and mollies can carry sperm for a long time after reproducing. Mollies can carry sperm for months and give birth multiple times with it. This is the same for guppies.

Even if you buy only female fish, chances are that they are already pregnant when they get home and will give birth.


You will be getting a lot of fry

You are keeping two species of livebearers in one aquarium. You will get loads of fry because breeding is what these fish are good at. If you have other species of fish in the aquarium, chances are that they will eat them.

If there are not that many hiding spaces throughout the aquarium, the adult mollies and guppies will also eat a couple of the fry.

You can buy dedicated fry food at your local fish store or online, but I would suggest that you crush up some of the regular food that you feed the adult fish. In my experience a lot of the dried fry food is just smaller grain adult food. An exception are for example these fish bites that are suitable for fry and available on Amazon.

Assuming that your aquarium is big enough and you are providing sufficient food, you will get a lot of fry that will quickly grow to be adults and start reproducing themselves. What do you do with all these fish?

There are several options. Firstly, you can see if there is an active local aquarium community in your local area. If this is the case, you can see if there are people interested in buying some of your fish. I can assure you that a lot of people would be extremely happy with a breeding pair of mollies or guppies.

The second option is to sell them back to your local fish store. I have succesfully sold a lot of guppies back to my local fish store. Typically they will not give you cash, but they prefer to give you store credit which you can spend at the store. For me that is not a problem because I am already spending money there.

What you should look out for is giving them away for free on social media or sites like Craigslist. If you give away 50 adult fish for free, chances are high that they will end up as feeder fish for predator fish like bass or oscars.

Male to female ratio

What is important if you are going to keep mollies and guppies together, is that you buy them in the correct ratio. I recommend getting between two and three female fish for every male fish, and this for both species.

So a good situation would be buying 2 male guppies, 2 male mollies, 6 female guppies and 6 female mollies when you are starting with no fish. Oh and by the way, just one male and 3 females for both species would also work because you will be getting babies soon enough.

Good luck to you! I hope you have found everything you were looking for in this article.

Related questions

How fast do guppies breed? Guppies breed like crazy. They can give birth every 2 to 3 months, and one batch of fry can consist of up to 50 babies. After a couple of months the baby guppies will grow to be able to reproduce themselves.

Molly image – Author: Gerardeen92 Licensed: CC4.0 No changes made
guppy image – Author: tartaruga33 Licensed under: Some rights reserved No Changes Made