Can Platy Fish Live in Cold Water Without a Heater?

When I first came across platy fish at a pet shop, I was sold a pair of platy being told that they are cold water fish; a phrase that I believe is still used by many pet shop owners.

But can platy fish actually live in cold water without a heater?

Well, it can’t! Since platy fish are originally a species of tropical water, it requires the water temperature to be between 75 to 80 degrees Fahrenheit or between 24 to 28 degrees Celsius to survive.

Apart from the water temperatures, there are a number of other things that you need to take into consideration to ensure the survival of platy fish in an aquarium.

Ideal Water Temperature

As a fish enthusiast and an aquarist myself, I have found one thing to be quite common among the fish keeping community, and that is the abundance of platy fish in our tanks. This is because when we are starting out on this hobby, we are looking for fish that are easy to manage and maintain. Such fish are called hardy fish in aquarist lingo. And more often than not, beginner fish enthusiasts end up buying platies because they probably are one of the most hardy fish out there. However, I have also heard many beginners complain about how their platy died because of cold water and how they were told that it is a cold-water fish.

Well, truth be told; it is not. While it is true that platies are tolerant to fluctuating water temperatures and currents, they absolutely cannot survive cold water. While I have already mentioned the ideal water temperature necessary for the survival of platies, mentioning it one more time with some added info would only help you better care for your platies.

So, the ideal water temperature inside the tank needs to be anywhere between 75 to 80 degrees Fahrenheit. The pH levels cannot exceed over 8.3 and cannot be below 7 with zero ammonia, zero nitrites and nitrates maintained under 40 ppm.

Since platies like to swim in hard waters, they enjoy extra alkalinity in their surroundings. So, remember to keep the alkalinity of the water at around 8 dKH and dGH levels at no more than 18. However, these details are specific to just platies. If you wish to keep other species of freshwater fish in the same tank as your platies, the water conditions inside the tank may have to vary a certain extent to accommodate all the species accordingly.

Different Types of Tank Heaters

Fish tank heaters come in multiple shapes and sizes; and which one should you choose depends entirely on the size of your tank. But before you go about choosing one for your aquarium, let’s learn about their 5 main types and the limitation of each and every one of them. This will help you to make a better decision.

  • The hanging heater, as the name suggests, this type hangs atop the tank while its heating element is lowered into the water. They are commonly used for freshwater fish and are ideal for beginner fish keepers.
  • The substrate heaters are usually used with other types of heaters. As they come in the form of wires, they are usually placed under the base of the tank. Substrate heaters are quite expensive and not used very widely these days.
  • The filter heaters are the most common type of heaters and have filters that come with heating elements combined. They come in a canister shape and heat the water as it goes through the filter.
  • The submersible heaters are placed under the water, right next to the filter inlet and heats up the water while it is going back into the tank. They are used for tanks that require a consistent water temperature.
  • Like submersible heaters and filter heaters, the in-line heaters are fitted between the filter or the sump pump and heats the water as it heads back into the tank. In-line heaters are mostly used in tanks housing larger species of fish.
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Choosing the Right Heater

While all the 5 heater types I mentioned are practical for one scenario or the other, the type of heater that’s right for your tank comes down to the size of your tank and the price you are willing to pay for the heater. The prevailing standard in the fish keeper community is 5 watts of heat per gallon of water in the tank.

This can also vary according to the temperature of the room where you keep your aquarium. Another thing to consider is that larger the volume of water, the slower it loses the heat and vice versa as long as you are dealing with smaller tanks.

To work out the accurate temperature needs for your tank, you need to subtract the temperature of the room, where the tank is placed, from your desired temperature. On a side note, you can check the packaging of the heater to see the size of tank it was designed for.

Ideal Tank Size for Platy

A known fact about platies is that they do not require too much space to live in and a single platy fish can easily survive inside a 5-gallon tank. While many fish specialists suggest getting a 10-gallon tank as it is ideal for many types of fish including the platies.

However, if this is your first time buying fish, I’d recommend getting a 29 gallon tank for your platies. A tank this big is especially helpful if you are planning to breed your fish as this provides them with extra space to stay active and let their fry grow freely.

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You will also have to remember to buy a filter and heater for your tank according to its size; something that many people do not give much importance to.

Related questions

What is the right spot to place the heater in my tank? The perfect or most convenient spot to place the water heater in your fish tank is close to the in-let of the water filter. Placing the heater near the in-let allows the water to heat up as it flows through the filter. The continuous cycle helps in keeping it warm and maintains a consistent water temperature. But this can vary depending on the type of filter you are using.

Is a single heater enough or should I get two for my fish tank? The number of water heaters you should own depends on where you live. If you live in a place where weather is usually cold, having two or more heaters can be very handy. It will not only take the strain off of the one, but the extra heater can be used as a back-up heater in case the one connected to the tank fails or malfunctions. It is also necessary to keep the water temperature at the same levels to ensure the sustenance of the fish inside the tank.

How do I keep a check on the operating condition of my heater? Along with following a regular maintenance cycle of your aquarium, you also need to keep a check on the tank’s water temperature on a daily basis. You can do this by using a thermometer on the opposite end of the aquarium. This helps in keeping track of the temperature of water inside the aquarium and to pick up any problems with the water heater.

What should I do if I do not wish to buy a heater for my fish tank? If you wish to keep freshwater fish or tropical fish in your tank, having a water heater is a must. However, if you do not want to buy a heater, you will have to drop the idea of getting platies or any other species of freshwater fish. Instead, opt for temperate fish species. One of the most common of these species is goldfish as it can easily survive at room temperature.

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Nadine Oraby

My name is Nadine; I am a passionate writer and a pet lover. People usually call me by the nickname “Joy” because they think that I am a positive and joyful person who is a child at heart. My love for animals triggered me to create this blog. Articles are written by vets, pet experts, and me. Thanks for visiting. Your friend, Nadine!

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