Can You Put Mollies in a Saltwater Tank?

Since mollies are hardy species of fish and originally live in brackish water where fresh and saltwater meet, they can tolerate the conditions in a saltwater tank. However, you need to acclimate them to these new conditions gradually to prevent shocks due to sudden changes.

If you want to find out more about mollies’ ability to tolerate saltwater aquariums as well as the reasons why transitioning them to these environments is a good idea, keep on reading this article!

Can You Put Mollies in a Saltwater Tank?

Common mollies (Poecilia sphenops) are species of fish that originally inhabit the brackish waters around Southern North America, especially Mexico and Columbia coasts.

The fish typically prefers living in conditions similar to its original habitat, but thanks to its flexibility and wide range of favorable conditions, the fish is capable of thriving in either purely freshwater or saltwater conditions.

In fact, you might end up finding mollies dwelling a few miles deep into the oceans surrounding where they live.

However, to avoid intense shocks while transitioning them, you need to do it over an extended period of time (about 6 to 12 hours) by using a slow dripping method.

Colorful aquarium Molly fishes

What Are the Optimum Aquarium Conditions for Mollies?

Mollies are among the hardiest fish that you can find out there, which makes them a perfect choice for a beginner hobbyist.

However, to help them survive the slow transition from freshwater to saltwater, you have to make sure that all other conditions within the tank are perfect for them.

For instance, you should also make sure that the water stays within a temperature range of 70 to 80 degrees F (optimum at 78 degrees F).

The size of the tank is also important, so make sure that you have at least a 10 gallon tank if you have about 3 to 4 mollies and add an extra 2 to 3 gallons for each new molly.

You should also use sand, gravel, and small rocks as substrate with loosely rooted plants and maintain the water hardness at 15 to 30 dKH while keeping the pH level between 7.5 to 8.2.

How to Acclimate Mollies to Live in Saltwater Aquariums

There are plenty of ways to acclimate mollies to live in saltwater aquariums. Some people reported that their fish immediately acclimated to saltwater by chucking them into the saltwater tank

However, the slow dripping method gives you the highest chances of success, as it extends the acclimation process over a window of hours, which gives enough time to the hardy fish to adapt to the new conditions.

One thing you should keep in mind is that there are some individual differences between mollies, even within the same species.

In other words, you should expect to lose 1 out of 4 mollies while transitioning them into saltwater. Here’s how to properly put mollies in a saltwater tank:

  1. Add your mollies to a large clean bucket and set it underneath the saltwater aquarium, and shut down the aquarium auto top off system.
  2. Add your mollies with the water they come in with into the bucket
  3. Get a clean airline hose of a suitable size and place one end of it into the aquarium and secure it inside without pinching the hose.
  4. Tie a knot somewhere along the airline hose to limit its drip rate.
  5. Get the other end of the hose and start sucking water out of the aquarium. Make sure that you’re doing it slowly and remove the airline before the water from the aquarium gets in your mouth
  6. Put the end of the hose in the clean bucket under the aquarium
  7. Adjust the knot by tightening it enough to allow about 1 to 2 drops per second but not too tight that water isn’t flowing.
  8. After every hour, come back to the setup to empty 1 to 2 gallons of water from your fish bucket and top off your aquarium with saltwater of the same salinity and temperature as the aquarium water.
  9. After 6 to 12 hours, the water in the bucket should be of the same salinity as the tank, so you’ll be able to remove the airline hose and add the fish to the tank.
  10. Turn the fish tank lights off to reduce the sensory stimulants and help your fish acclimate

The Advantages of Adding Mollies to Your Saltwater Tank

Now that you know more about mollies and how to add them to your saltwater tank, you might be wondering about the benefit of doing that.

One of the main reasons to add mollies to saltwater tanks is that they will help you clean the aquarium, as they mostly feed on algae.

Additionally, as feeder fish species, they can produce between 40 to 100 fry every 60 days, which keeps the nutrition inside the tank sustainable.

Moreover, mollies are incredibly affordable and hardy when compared to saltwater species, which makes them ideal for first-time saltwater fish tank owners.

What Types of Mollies Can Tolerate the Saltwater Environments?

Technically speaking, all types of mollies that live in Brackish environments can survive in a saltwater aquarium, provided that you transition them gradually using the slow drip method and maintaining all other favorable conditions as much as possible.

However, there are some species that are hardier than others, and therefore, can tolerate the transition easily and survive in saltwater. These species include:

  • The common or short-finned molly (Poecilia sphenops)
  • Thee sail-fin molly (Poecilia latipinna)
  • The Yucatan or giant sail-fin molly (Poecilia velifera)

Wrap Up

There you have it! A complete guide with everything you need to know about mollies and whether you can put them in a saltwater tank.

As you can see, the feeder fish can easily live in saltwater aquariums when the water transitions gradually.

The hardy fish is a great addition to your fish tank and comes with tons of advantages that make it an excellent start to saltwater aquarium keeping!