Basic Facts About Mollies
| Scientific Family: | Poecilia |
| Number of Molly Fish Species Types: | There are roughly 40 individual species of Mollies within the Poecilia family. Nearly all fish within the Poecilia family are Mollies. |
| Average Life Span: | The average lifespan for a Molly fish is about five years. |
| Typical Size: | Mollies are generally smaller fish and will generally grow to about four inches. The largest Molly fish species can grow up to five inches. |
| Colors: | There are a number of different species of Mollies that come in many different colors. The most common are silver mollies, but Molly fish can range from black, to orange and white. Some Mollies are even speckled like dalmatians. |
| Native To: | Species of Mollies can be found in the coastal regions of the Southeastern United States, as well as Mexico and Central America. As they occur in coastal regions in the wild, Mollies can live in freshwater and brackish water. |
| Water Conditions Needed: | Temperature: 72-82°F. PH Level: Mollies can live in a wide range of PH levels from 6.7 to 8.5, however they thrive in higher PH levels with the optimal being around 8.0. |
| What Do Mollies Eat?: | Mollies are omnivores, meaning they’ll eat a wide variety of foods. Mollies will eat most types of flake food but those foods should be supplemented with something high in protein, like bloodworms. Mollies will also eat algae as well as some vegetables that you can find in your kitchen, like zucchini or lettuce. |
| Fish-Keeping Experience Level: | Mollies are very low maintenance fish and are a great fish for beginners. They’re one of the easiest fish to breed and their diverse colors make them a great way to introduce a child to the hobby. |
| Minimum Tank Size: | Depending on the species of Mollies that you choose, a ten gallon can be suitable for Shortfin Mollies however for the larger Sailfin Mollies, we would recommend at least a 20 gallon tank. |
| Tank Accessory Requirements: | In the wild, the Molly’s environment is often shallow water with many plants and submerged places for them to hide. We would recommend that Molly tanks include live plants and driftwood. If you’re planning on breeding them, floating plants, like Dwarf Water Lettuce make excellent hiding spots for the fry. |
| Compatibility – Other Species: | Mollies do well in groups and are generally suitable for community tanks. The males can sometimes be aggressive and have been known to nip the fins of other fish. Fish like Platies, swordtails, neon tetras, lemon tetras and bristlenose plecostomus are great tankmates for Mollies. You should avoid larger more aggressive fish as tank mates. |
| Compatibility – Plants: | We recommend keeping Mollies in a planted aquarium. Floating plants like Dwarf Water Lettuce, stem plants such as Cabomba or Bacopa or rooted plants like amazon swords are easy to grow and will help your Mollies thrive. |
| Compatibility – Do not Keep With These Species: | We would recommend avoiding larger, more aggressive fish for Molly tankmates. South American and African cichlids are not suitable tankmates for Mollies. |
| Can you breed them? | Yes. Mollies are relatively easy to breed in the home aquarium. Mollies are live-bearers which means that they give birth to live fish, rather than lay eggs like most other fish. Mollies generally prefer warmer water to breed, between 78-82°F. If you’re planning on breeding Mollies, it’s recommended to keep three to four females for each male in your tank. Females are generally rounder than males and when they’re expecting fry, their stomachs become swollen. |
| Fun Fact: | Mollies were the first freshwater aquarium fish that we ever got to spawn! |
| Cost: | $3-5. Mollies are relatively inexpensive fish to purchase. Your local pet store will likely carry several varieties that will range from $2.50-$5 in price. |
How will a Molly Fish behave in your aquarium?
Mollies are generally peaceful fish. They prefer to swim around towards the top of the tank and are generally very active, flitting around the surface of the water. Occasionally, they may nip each other’s fins but nothing that would cause permanent damage. They prefer to have some sort of cover and space to hide and live plants will help mimic their natural environment.
How to acclimate your Mollies to your fish tank?
Mollies can be acclimated by the floating method, detailed below. As Mollies are very hardy fish, they are easy to acclimate to your home aquarium. Mollies are unique in that they’re one of a few aquarium fish that can be acclimated to saltwater tanks as some varieties can live in brackish water in the wild. If acclimating Mollies to saltwater, you can use the guide below for the drip method as well.
Floating Method:
Step 1: Place the bag with your Mollies in your aquarium & cut off the lights. While they likely had the light on in the pet store, keeping them close to the lights of your tank may unintentionally heat the water in their bag more than you wanted to.
Step 2: Let the bag float for 10-15 minutes to reach the same temperature as the tank.
Step 3: Cut a small hole in the bag and allow some of the water from your aquarium to flow in until it makes up roughly half of the water in the bag. Allow the bag to continue to float for about 5 more minutes, this will allow the Mollies to ease into the water parameters of your tank
Step 4: Release the Mollies into your tank!
Drip Method for Saltwater Acclimation: Note that this is difficult to get right, we’d recommend this only for experienced aquarists.
Step 1: Place your mollies in a container of water below the waterline outside of your saltwater tank. Breeder boxes or a five gallon bucket will work great for this.
Step 2: Take a small piece of airline tubing and run one end into your salt water tank and the other into the freshwater container.
Step 3: Begin the siphon and allow it to drip saltwater into the container of freshwater.
Step 4: Allow the bucket or container to slowly fill over a long period of time. When filled to the point where most of the water is saltwater, your Mollies are ready to go into your aquarium. Note that this may take several hours, even overnight. Just make sure that you don’t overflow your container!
Which Species Are Best To Pair With Your Molly?
- Other Mollies
- Small Tetras, such as Neon Tetras, Lemon Tetras or Cardinal Tetras
- Bristlenose Plecostomus
- Small barbs, such as cherry barbs or gold barbs
- Cory catfish
Most Common Types of Molly Fish
- Silver Mollies
- Black Mollies
- Dalmatian Mollies
- Sailfin Mollies – for example, there can be Black Sailfin Mollies. The Golden Sailfin Molly is a common Molly of this type.
- Lyretail Mollies – for example, there can be Silver Lyretail Mollies. The Platinum Lyretail Molly is a common Molly of this type.
- Gold Dust Mollies
- Balloon Belly Mollies
- Gold Doubloon Mollies
Ohfishal Molly Fish Tank Set Up
This is our ultimate checklist for a set up for Mollies. Below is everything you need for a great habitat for Mollies! Of course, you can do this with less parts, or different parts, but this is our all-in ohfishal recommendation. This set-up will run you around $180 (market prices will vary).
- Fish Tank – Aqua Culture 29 Gallon Aquarium Starter Kit with LED – If you want to buy an entire set with everything you need, this is a great option! Includes a LED light and a Tetra Filter. ($125)
- Species – 4 Mollies ($12-20), 1 Bristlenose plecostomus ($5), 6 Neon Tetras ($12-15), Dwarf Water Lettuce ($5), Java Fern ($5), Small Driftwood ($10-15)
Frequently Asked Questions about Mollies
Molly fish go well with most smaller community fish. Tetras & Cory Cats are two of our recommendations but they can go with other livebearers such as platies or guppies as well!
Molly fish generally have a gestation period of about 6 weeks, after which they’ll give birth to between 20 and 60 live babies.
Yes, most Molly fish are the same species and can reproduce regardless of any color differences.
Molly fish are not very aggressive but can become aggressive when paired off. They will actively defend themselves but in general are great community fish.
Most male Molly Fish will stay under four inches while the females will be slightly bigger. At their largest, some have been known to grow up to five inches.
