Can Mollies Live in a Pond? (7 Tricks to Ease the Transition)

A fish pond can be the perfect centerpiece to complete a serene backyard. The only issue here is that not all fish are compatible with living in freshwater ponds.

So, can mollies live in a pond?

Yes, you can raise molly fish in an outdoor pond, especially in the summertime when the temperature is between around 80 degrees F. Plus, the any salt content in the pond is not an issue at all for mollies.

Unfortunately, it’s still not as easy as filling a ditch with water, throwing fish in, and calling it a day.

With the right maintenance schedule, you can turn an outdoor pond into a balanced ecosystem for your fish.

Group of Yellow Mollies

How Can Mollies Live in a Pond?

Ponds are freshwater bodies, and normally, moving saltwater fish into freshwater ponds would mean killing them.

That’s because their bodies are loaded with a high concentration of salt that would cause an osmotic disturbance. In only a few minutes, the saltwater fish would bloat and die.

Thankfully, that’s not the case with mollies.

Mollies are euryhaline fish, meaning that they can tolerate different levels of salinity from fresh, brackish, and salty water bodies.

The name “euryhaline” is a combination between the Greek words “eurys” and “halo,” which mean “wide” and “salt,” respectively.

Ditching all the technical jargon aside, a molly can osmoregulation the water levels inside its body regardless of how concentrated the dissolved salts are.

It might sound like something out of a science fiction movie till you think about it and realize that we too are euryhaline!

How to Adapt Mollies to Freshwater Ponds

Although salinity isn’t a big deal for molly in a pond, there are still a couple of factors to keep in mind.

Here are some useful tips to help you raise mollies in an outdoor pond:

Move Your Mollies Inside for the Winter

While mollies aren’t exactly high-maintenance, they can be a bit unforgiving when it comes to temperature changes.

Under 80℉, your fish might survive, but they won’t be able to go on with the regular breeding cycle.

Ideally, you don’t want the temperature to drop below 70℉, and you can’t expect mollies to live if the pond surface gets frozen on top.

To deal with that issue, you can either move the fish into an indoor aquarium during the winter or invest in a pond heating system.

Use Shading Trees to Your Advantage

While freezing cold water is a more serious threat to your molly pond, overheating is still a possibility.

Mollies can survive without any direct sunlight falling on their habitat.

Meanwhile, too much heat can speed up the decay process of food remains, making the maintenance that much harder.

Generally, partial shade works best for fish ponds. So, this might be worth considering if you’re still picking a spot.

Maintain a Steady Supply of Oxygen

Just because you’re moving the fish outdoors doesn’t mean they’ll get their full oxygen demand from the air.

If you’re using a shallow pond to raise the mollies, you can get away with not attaching a pump since the fish movement itself could be enough to aerate the water.

Even then, this should only be a temporary situation.

To move on with the fish pond, you’ll definitely need to get an oxygenator pump to circulate the water from top to bottom.

Don’t Worry Too Much About the Salt Content

Since mollies are euryhaline, you don’t have to do much to help them adapt to a change in water salinity levels.

The process mostly breaks down to gradual adaptation by dripping some of the fresh pond water into the temporary bucket to let the fish acclimate.

However, you’ll need to worry about other parameters like the pH level.

Mollies produce a lot of alkaline excreta, and you need to keep the pH neutral at around 7.5 or 8.5. Use a water probe to get accurate readings.

Vacuum Some (Not All) of the Algea Away

Besides using a water filter, it might be easier to get a vacuuming system to suck up all the accumulating algae and food remnants before they decay and contaminate the water.

It’s also a good idea to schedule a water change seasonally. It’s a chance to clean up the filters and give the pond bottom a thorough cleaning.

However, we recommend leaving a tiny bit of algae behind.

That’s because algae help keep the ecosystem balance in check by absorbing nitrates. Instead, you can remove only any excessive or decaying algae.

Keep an Eye out for Overpopulation

Mollies are a hardy breed. They won’t only survive the outdoor conditions, but they’ll also increase in population from a dozen to a hundred in under a year.

In a single birth, a live bearing molly can carry anywhere between 40 and 100 fry!

Sometimes, birds and other prey in the area naturally take care of overpopulation and habitat degradation. Other times, you’ll need to intervene.

To nip it in the bud, you can harvest medium-sized fish every now and then and consider giving them up for adoption.

Don’t Shy Away from Socializing Your Fish

Most mollies will adapt nicely to the surroundings, even if this is a pond in a park, a backyard, or some spot with a lot of foot traffic.

Ask anyone who raises mollies in an aquarium.

They’ll tell you this species loves human interaction, and they get along with different types of fish without much fuss.

Keep in mind that they can still be vulnerable to predators, whether it’s other fish in the pond or birds.

The Takeaway

Circling back to the question: Can mollies live in a pond?

In short, yes, it’s absolutely possible to raise mollies in a pond.

It’ll take a bit of consideration when it comes to oxygenation, cleaning, and balancing the population.

However, it shouldn’t be too difficult once you get the hang of it. Plus, looking at the pond will make it all worth it in the end!