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Molly Fish Beginner Care Guide

Updated: Apr 19, 2021


With the wide variety of colors and types of mollies available it is no wonder that molly fish are so popular among fish keepers. These fish have an average lifespan of 5 years and typically get to be around 4 inches in size.

They are very social fish so it is typically recommended to purchase them in groups of 4-6 at a time, and because of their larger size a minimum tank size of 20 gallons is typically recommended, however a larger tank of at least 30 gallons would be more suitable.

Tank Set Up

Mollies are a tropical fish and will typically require a heater as they need their water to be kept at stable temperatures between 78-82 Fahrenheit.

These fish tend to prefer harder water with a ph from 7.5 to 8.5 and so many hobbyists with softer water will keep items like crushed coral in the tank to help buffer the water.

Higher filtration is also often recommended when keeping mollies, as they do tend to create a larger bioload in the aquarium.

When setting up a tank for mollies you will want to first decide if you will set up a brackish or freshwater tank for them.

As it is common for mollies to be bred and kept in brackish waters, if you are wanting to keep mollies in a purely freshwater tank, it may be best to look for a breeder that specifically breeds mollies in freshwater, rather than going to the pet store, as many of the mollies you will find in pet stores were bred in brackish water, and may not do well immediately switching over to freshwater.


Mollies are omnivores and will naturally feed on algae and plants, they are also typically fed a varied diet of high-quality flake food, vegetables such as blanched zucchini or cucumber, bloodworms, baby brine shrimp, and daphnia.


Mollies are livebearers and when getting mollies for your tank, it is also important to know that males do tend to be aggressive when it comes to breeding so you will want to have at least 3 females for each male in the tank.

Male mollies tend to be more streamlined in shape with larger fins and have a more pointed anal fin. While female mollies typically have bulkier bodies, shorter fins, and a more fan like anal fin.

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