Can Black Mollies Live In Cold Water? (Solved!)

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Can Black Mollies live in cold water? No, Black Mollies can not live in cold water. Black Mollies are a tropical species of fish and as such need to be kept in water which is between 76°F and 80°:F (24°C to 26°C). For most aquarium setups, Black Mollies will require an aquarium heater to raise the temperature to a sufficient level.

Black Mollies are probably one of my favorite fish. They are undemanding, easy to breed, and don’t really cause any trouble in the aquarium. This year I was looking to put some raised ponds outside to keep and breed fish in. Someone suggested Black Mollies.

One thing we should discuss at this point is the term ‘cold water’. I have read articles where people say ‘Mollies can live in cold water, providing it isn’t colder than 72°F’! This is clearly misleading.

In my article, I am working on the theory that a tropical aquarium is one where the temperature is above 70°F (21°C) and a coldwater aquarium is one where the temperature is less than 70°F.

Can Mollies SURVIVE In Cold Water?

Mollies are extremely hardy and adaptable. They can survive extremes of cold and warm temperatures for short periods. If your aquarium heater packs up and the water temperature drops to 65°F (18°C) for a few days, the chances are your Black Mollies won’t worry at all.

A drop in temperature for a short period is very different from living in cold water all the time. If your aquarium water temperature is dropping low on a regular basis, your Black Mollies will become stressed.

A stressed fish is susceptible to pests and diseases which are present in the aquarium. Ich, also known as Whitespot, will take advantage of any fish which is stressed and has a compromised immune system as a result of being stressed.

What Are The Effects On Black Mollies Living In Cold Water?

Black Mollies living in water that is too cold for them, will undoubtedly be stressed. Fish which are stressed are more susceptible to pests and diseases living in the aquarium.

Black Mollies also rely on water temperature to help control metabolism. Black Mollies Kept in warm water will eat more food and grow faster. Black Mollies kept in cold water will usually eat less and they will certainly grow more slowly, or may not grow at all.

Pregnant female Black Mollies that are kept in water that is too cold may find their babies don’t grow fast enough, or even at all. Pregnant female Black Mollies may well abort then reabsorb the unborn baby fish if their aquarium water is too cold.

Can Black Mollies Live Without An Aquarium Heater?

Essentially, an aquarium heater’s sole job is to keep the water temperature at a preset level. Black Mollies can live without a heater, providing the natural air temperature is sufficient to keep the aquarium water within a suitable temperature range.

With that said, even those living in warmer climates where the air temperature is sufficient to keep the aquarium warm enough should still consider adding an aquarium heater, just in case the water temperature does dip too low.

What Is The Ideal Temperature For Black Mollies?

As discussed above, Black Mollies are a tropical species of fish. As such they require water which is warm. Black Mollies need their aquarium water to be somewhere between 76°F and 80°:F (24°C and 26°C).

Black Mollies can survive for short periods on either side of these temperatures, but you should always aim to keep the temperature stable and within the desired range.

Black Mollies are hardy and adaptable. Small fluctuations in temperature over short periods will not bother them at all.

Can Black Mollies Live In Ponds?

The simple answer is yes, Black Mollies can live in ponds, but only with the caveat providing the water temperature is at somewhere in the region of 76°F to 80°F (24°C to 26°C).

Technically a pond is just a means of holding water, just like a fish tank. The fish don’t care what their water is held in, but they very much DO care about the temperature of the water.

If you keep Black Mollies, why not check out my article Do Black Mollies Eat Black Beard Algae?

In Conclusion

In answer to the question, can Black Mollies live in cold water, the answer is NO, Black Mollies can not live in cold water. They need to live in water that is held at the correct temperature.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James

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