What Is The Ideal Water Temperature For Molly Fish?

If you consider keeping Molly fish in your aquarium, there are various elements you must look for and maintain properly. Providing an absolute water temperature is significant for their healthy survival among many of them. But what is the ideal water temperature for Molly fish?

The ideal water temperature for Molly fish is between 72 and 78 degrees Fahrenheit, and it is crucial to manage this absolute water degree for their safer endurance in the aquarium. Remember, these are not room temperature but water temperatures!

However, Mollies can adapt to a wide range of water temperatures. Yet, the stated water degrees are ideal that boost them to thrive and survive pleasantly.

Here is an article entirely dedicated to letting you know about the ideal water temperature for molly fish.

Minimum Water Temperature For Molly Fish

You might know the Molly fish are tropical freshwater fish. They cannot adapt to any casual water degree in the aquarium, not even for the minimum level. So, it is essential to maintain an ideal minimum water temperature to let them thrive and live wholesomely.

The minimum water temperature in the aquarium needed for Molly fish is 72 degrees Fahrenheit. This water degree provides the suitable minimum warmth to them that keeps them flourishing. 

Since Molly fish are hardy fish, they can adjust to a somewhat lower temperature than 70F. Yet, an ideal water warmth satisfies their living by keeping them healthy in the aquarium.

What Happens If The Water Temperature Is Lower Than Ideal Minimum Temperature?

Your tank must hold at least 72 degrees Fahrenheit of minimum water temperature to secure a healthy life for Molly fish. If the temperature drops from this level, your fish will certainly experience fatal conditions later.

Mollies will start feeling dull and lazy as the temperature drops down. They will then stop to interact and swim actively. So instead, they stay isolated in some hiding spots in the tank.

You may also see some of them getting aggressive and fighting in this situation. Such activities will not just affect Mollies but their tank mates as well.

Not only this, but the metabolism in their body will get extremely low as the water temperature starts dropping for a longer time.

You may even notice your Mollies declining their appetite too. Your fish cannot even adjust despite being hardy fish in this situation.

However, Mollies may adjust and survive if the water temperature is lower than ideal, but its consequences will appear slowly.

It then affects their health and may invite some critical life-threatening situations too. Therefore, it is significant to maintain an ideal minimum water temperature for Molly fish.

How To Control Low Water Temperature For Molly Fish?

If you see or want to prevent the water temperature from dropping down than the minimum level required for Mollies, you can use:

Aquarium Heater

Since you are fond of keeping fish, the equipment you may be familiar with is Aquarium Heater. It can be the best option for you to control the dropping water temperature of your Molly fish aquarium. It would help if you had an aquarium heater for your molly fish to survive in the tank environment.

In an aquarium heater, a mark shows how high the water temperature should exactly get or limit. Here, you can set the temperature limit in the heater. 

Later, if you see the water temperature fluctuating, the heater will operate and reach the specified mark.

Don’t worry! This equipment will not exceed the set mark and manage the water temperature. But make sure you fix the heater mark by realizing the maximum water temperature required for Mollies.

In this way, an aquarium heater controls the low water temperature by precisely maximizing the heat required for Mollies. You can surely set up this equipment to ensure the correct water temperature for your fish.

Using An Aquarium Thermometer

Since you maintain a low water temperature in the tank, I suggest getting an aquarium thermometer. 

It helps to identify the exact current water temperature of your aquarium. If there is any temperature change, this thermometer will let you know immediately.

Maximum Water Temperature For Molly Fish

Once you settle the minimum water temperature for Molly fish, don’t assume managing the water temperature matter is over. The work still is incomplete until you maintain an ideal maximum water temperature for them.

So, the ideal maximum water temperature for Molly fish in the aquarium is 78 degrees Fahrenheit. If your fish lives under this maximum water warmth, they are likely to endure with ease without discomfort.

However, you might have heard that this fish can settle up to 78 degrees Fahrenheit maximum in the tank. Yet, the ideal maximum water temperature is the margin where your fish forcefully don’t adjust.

What Happens If The Water Temperature Is Higher Than Ideal Maximum Temperature In Molly Fish Tank?

Imagine you are in a room that has a very high temperature! Will you get bothered or react with ease? Of course, you will be irritated and annoyed. Plus, things can get worse if didn’t take quick action. 

A similar experience will even your Molly fish face if the water temperature in their tank is higher than ideal. And indeed, you don’t want this to happen!

If the water temperature is higher than the ideal maximum temperature, the water will get too warm than required.

It is not safe for Mollies mentally and physically. They will start stressing and feel discomfort and dullness. Your Molly fish are also likely to lose their calm and get aggressive when the tank’s water temperature increases.

Here, Mollies may chase and attack their tank mates suddenly. Their behavior towards everything gets harsh and rough as their anger in such an environment peaks.

Your fish will slowly lack appetite as their activeness changes into dullness. When they don’t eat properly, they don’t intake nutrition to make their immune system strong. Thus, there will be a high chance of catching life-threatening fish diseases.

Besides, the metabolism in the Mollies’ body starts speeding rapidly in an exceedingly warm water temperature.

It ends up shortening their life expectancy. And unfortunately, your adoring fish may die sooner. 

Therefore, maintaining an ideal water temperature for Molly fish is vital for enduring healthily in the aquarium.

How To Control High Water Temperature For Molly Fish?

Sometimes, the water temperature may get low but can reach high degrees than required. Such condition is essential to observe and reform as soon as possible. 

Thus, to control a high water temperature in the tank, you can use:

Aquarium Chiller

If you are a beginner aquarist, you may be unknown about an aquarium chiller. This equipment is like a small tank refrigerator that cools down the high water temperature.

An aquarium chiller works by using compressed gas to decrease the heat from the tank and moves it to a radiator, where a fan blows it out from the device. It has a controller that observes the water temperature of the tank.

Here, you can set a mark of maximum water degree on this device. It then works automatically by turning the system ON if the temperature exceeds the entered mark. Also, it will turn OFF once the temperature cools down to the required level.

You can install an inline chiller with an external aquarium filter to cool the water. It usually makes the function of the chiller easy to pass away the heat from the system.

Is An Aquarium Thermometer Essential While Using A Chiller?

Yes, an aquarium thermometer is essential while using an aquarium chiller. 

As stated before, this thermometer helps you to show any fluctuation happening in the water temperature. In addition,itt makes you aware that your Mollies are possibly at risk. 

However, an aquarium thermometer is unnecessary if you have a thermoelectric chiller. Such chillers include the operation function of the thermostat to lower the water temperature. Therefore, it helps you control the high water temperature without requiring an aquarium thermometer.

Tips To Follow While Maintaining Ideal Water Temperature For Molly Fish

As you maintain an ideal water temperature for your Molly fish, here are a few tips that you shall follow:

  • While managing water temperature for Molly fish, don’t forget to uphold the pH level of 7.5 to 8.5. 
  • Do not go for more than 25% to 30% of freshwater at once when you change the tank water. Otherwise, it can stress the fish. Also, avoid using tap water in the tank during the whole water changing process for molly fish.
  • Try not to keep Mollies in somewhat low or high temperatures than the ideal range. It seems normal as they can adjust to it but slowly, it affects their health.

Frequently Asked Questions

You might have more questions related to the molly fish. I tried to answer some of the FAQs people often ask.

Do Molly Fish Need Filter?

Yes, Molly fish do need a filter in an aquarium. It performs definite water circulation, aerates in the tank, and manages some aquarium beneficial bacteria. These factors are vital for Mollies to thrive in the aquarium as these bacteria perform the aquarium nitrogen cycle. This cycle converts the toxic ammonia to essential nitrate in the tank.

How Long Do Mollies Live?

Mollies live for 3 to 5 years longer on average. However, their longevity is likely to extend for long if proper care and nourishment are provided.


In conclusion, water is a fundamental element for the survival of Molly fish or any other species; well, it is an aquatic animal, so it’s given. Likewise, an ideal water temperature also upholds their living. I know Molly fish are hardy fish. But it doesn’t mean negligence in maintaining water temperature is pleasant. On the contrary, such oversight will gradually harm your fish, which I think you don’t wish to happen. 

Thus, always intend to keep a correct water warmth for your Mollies if you wish to see them thriving better.

Please get in touch with your vet or drop your queries in the comment section below if you have any problems.

Good Luck!!

Hope Your Enjoy The World Of Fishkeeping!!