Do Tropical Fish Need A Heater

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Last Updated on 2023-05-24

If you’re new to the aquarium hobby, you might find yourself overwhelmed by the amount of information out there. Learning anything takes time and effort, and keeping an aquarium is no different. But the good news is that the more you learn, the easier and more rewarding it will be in the long run.

Raising and caring for tropical fish has its own set of challenges, and the environment in your tank needs to be ideal for your fish to thrive. In this article, we will discuss the reasons why you need a heater for your tropical fish and share some information on which fish can survive without one.

Do Tropical Fish Need a Heater?

Tropical fish in the wild live in warm waters, which means you will need a heater to keep the water at a consistently warm temperature. This will keep your fish healthy, boost their immunity from diseases, keep their colors vibrant, and ensure they will be livelier. Without the right water temperature, tropical fish are at risk of a lowered life expectancy and will be generally unhealthy.

When we put an aquarium in our homes, the water temperature will quickly match the temperature of the room it’s in. And while most people might think their homes are generally warm enough to keep the water temperature warm, this isn’t the case.

Tropical fish need a consistent temperature between 75-80 degrees Fahrenheit (23.88-26.66 degrees Celsius) to thrive. So, if the temperature in your home drops overnight, even by five or ten degrees, then the temperature of the water in the aquarium will drop as well. Putting a heater in the aquarium guarantees that your fish will have a steady temperature in the range their accustomed to in the wild.

Why Do Tropical Fish Need a Heater?

·         Fish Are Cold Blooded

Being cold-blooded means fish cannot generate their own body heat and cannot regulate their body temperatures like mammals can. Their body temperature will quickly match that of their surroundings, which means when the water is too cold, the fish are too cold as well.

·         Tropical Fish Live in Tropical Waters

The term tropical fish generally refers to fish that require a heated aquarium. They generally come from tropical environments where the water temperature is very warm, and recreating that in a home habitat is essential for their health and survival.

·         Fish in The Wild Can Migrate

In the wild, the water of lakes, streams, and the ocean is variable depending on the depth. The deep waters are colder, while the water near the surface is warmer because it’s warmed by the sun. Fish in the wild can move to warmer waters when the temperature is too cold for them. Aquarium fish don’t have that luxury.

·         A Heater Guarantees a Consistent Temperature

Tropical fish need a consistent temperature of around 78%. Installing a heater in your aquarium helps to guarantee they won’t be subjected to fluctuations in temperature that occur because of the environment of your home.

·         It Keeps Them Healthy

If the water in your aquarium is too cold, your tropical fish will suffer and be generally unhealthy. They will live shorter lives, be more susceptible to disease, and may be lethargic and tired. Keeping the water at an ideal temperature will keep them healthier and will keep their colors brighter and more vibrant.

a corner of aquarium with water filter and electric heater

Do Goldfish Need a Heater?

Goldfish are considered cold-water fish and do not require a heater. They typically do well in a tank at room temperature. The only time you might consider a heater for a tank with goldfish is if the temperature in your home is cooler than normal. Putting a heater in with goldfish can make the water too warm and could seriously harm them or lead to an early death.

It’s important to note that there are a variety of species of goldfish, and because of this, they may have a slight variation in their desired water temperature. For example, slim-bodied goldfish can survive water temperatures near the freezing point. But fancy goldfish need a water temperature that is above 55 degrees Fahrenheit.

The one constant when it comes to goldfish is that no matter what temperature they prefer, that temperature needs to be consistent. In general, they require temperatures between 50-75 degrees Fahrenheit. Avoid temperatures above or below this range, and make sure any temperature changes you make are gradual to avoid stressing or shocking them.

Do Molly Fish Need a Heater?

Mollies are classified as tropical freshwater fish, and they come from warmer climates. Mollies prefer a temperature between 70-82 degrees Fahrenheit. This temperature range might be a little lower than is required for some other tropical fish, but it is still preferable that their tank has a heater to keep their water at a consistently warm temperature.

Mollies are also very susceptible to sudden temperature changes, so be sure when you’re attempting to raise or lower the temperature in your tank that you do it gradually. Changing the temperature too quickly can stress the fish and even cause them to die.

Do You Need a Heater for a Betta Fish?

Betta Fish are usually seen in the pet store and kept individually in small cups or bowls. So, you might be wondering if these fish require a heater in their tank when you bring them home because they didn’t have one at the pet store. Unfortunately, the answer is yes, and the fish you see at the pet store without warm water is probably unhealthy and unhappy.

Betta fish are native to areas like Cambodia, Thailand, and Malaysia. These are fairly tropical and warm environments, and beta fish require this same temperature when kept in a home aquarium. Betta Fish thrive at temperatures between 76-81 degrees Fahrenheit, and the upper range of that measurement is ideal.

Betta fish may be able to survive at temperatures slightly lower than this, but they will be unhealthy, prone to disease, and will have shorter lifespans.

Do Guppies Need a Heater?

Yes, Guppies should be kept in a tank with a heater. Guppies may be able to survive at temperatures a little lower than some other tropical fish, but using a heater in their aquarium will ensure they have a consistent temperature.

Maintaining a stable temperature for your guppies will help keep them healthier and ensure they live long, happy lives. Guppies are very resilient, but fluctuations in water temperature, especially when those fluctuations are drastic, can have negative effects on their health.

If you live in a very warm climate and can maintain a water temperature of between 74-82 degrees Fahrenheit, you may get away with not using a heater for your guppies. But it’s never a bad idea to use one just to make sure that water stays at the right temperature.

How Long Can a Tropical Fish Live Without a Heater?

If you’re a responsible aquarium owner, there will be times when you will need to remove your fish from the tank. This includes those occasions when you change the water or clean the tank and sand. These are required tasks that aquarium owners should do regularly to make sure their tanks are free of rotting food and debris and stop the growth of potential bacteria.

You might be wondering how long a tropical fish can survive outside of its heated tank. That depends on the kind of fish you’re dealing with. Generally, tropical fish can survive in cooler waters for at least six hours. Some can be ok for as long as one to two days.

So, if you’re goal is to clean a tank, removing the fish to a bucket of warm water for a short amount of time should be ok. There are other reasons an aquarium could be left without a heater, like when there’s a power outage or the heater in your aquarium suddenly stops working.

During these times, you can take some preventative measures to make sure the water in your tank stays warm for as long as possible. And it’s a good idea to monitor your fish for signs of ill health, like lethargy and lack of appetite.

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What Tropical Fish Do Not Need a Heater?

Remember that, in general, the term “tropical fish” is used in the aquarium hobby primarily to describe fish that require warm waters and will therefore require a heater. But there are some species of “cold-water” fish or fish that thrive in water that is not quite as warm as your typical tropical fish require.

·         White Cloud Minnows

Native to China, the White Cloud Minnow is a great choice for beginner aquarium hobbyists because they’re easy to care for and adapt well to tanks with other inhabitants. They are usually found in mountain streams and rivers and can tolerate temperatures between 64-72 degrees Fahrenheit but can survive in waters up to twenty degrees cooler.

·         Blind Cave Tetras

Also referred to as the Mexican Tetra, this strange little fish gets its name from the variant species that has no eyes. They are born with eyes that are reabsorbed within a few weeks, leaving them completely blind. Because they’re native to cave systems where there is little to no light, it’s believed that they evolved to better adapt to these environments.

There is also a species that has eyes and can see just fine. The Mexican Tetra thrives in the cooler waters of caves and like temperatures between 68-77% Fahrenheit.

·         Zebra Danios

Zebra Danios is another popular choice of fish for beginners setting up their first aquarium. They are exceptionally hardy and can tolerate a wide range of water temperatures. They will thrive in temperatures anywhere from 65-75 degrees Fahrenheit. They are known for being very active and doing well in groups of six or more. They have striking black stripes.

·         Comet Gold Fish

Also called the comet-tailed goldfish, these hardy fish can survive in water that is between 60-75% Fahrenheit. They will generally do well in a tank without a heater unless the temperature in their environment is significantly colder than normal. They come in a variety of vibrant yellow, orange, and red hues but can also be bred to be white, brown, or black. They are hardy and adaptable.

·         Rosy Barb

Considered a subtropical fish, the Rosy Barb is a popular choice for aquarium hobbyists because of their temperament and bright colors. They originate in the rivers of India and Bengal and can tolerate temperatures between 64-72 degrees Fahrenheit. They are very social fish and can tolerate a wide variety of tankmates, and can grow up to six inches in size.

How to Keep a Fish Tank Warm Without a Heater

If your aquarium is left without a heat source for an extended period, it may be necessary to take steps to keep the water temperature as warm as possible. Here are a few ways you can accomplish this until you can replace the heater in your aquarium.

·         Add Sealed Water Bottles

Adding sealed hot water bottles to the tank water can increase the water temperature. Make sure to add them one at a time and then monitor the temperature with a thermometer, so the water doesn’t get too warm. Never add boiling or hot water directly to the tank.

·         Move the Tank

Simply moving the tank to a warmer room, next to a heater, or even near a window with direct sunlight can help keep the water warmer.

·         Wrap the Tank in Bubble Wrap

Bubble wrap is a great insulator. So, if you find yourself without a heater, try wrapping the aquarium in bubble wrap to keep the remaining heat in the water for as long as possible. Bubble wrap is also a great choice because you can see through it and are therefore able to monitor the condition of your fish.

·         Wrap the Tank in Towels or Blankets

Wrapping an aquarium in warm towels or blankets can help to insulate it and keep the temperature of the water a few degrees warmer for a while.

·         Insulate With Styrofoam or Cardboard

Mounting Styrofoam or cardboard on the outside of the tank can help insulate it and keep the water temperature warmer.

Frequently Asked Question

What Kind of Heater Should I Buy?

There are four basic types of aquarium heaters.

  • Submersible heaters can be completely submerged in the aquarium and usually stick to the side of the tank. This is the most effective type of heater.
  • Immersible heaters are usually hanging-style heaters that are immersed right at the waterline.
  • Substrate heaters are buried beneath the sand or gravel at the bottom of the aquarium and are better suited to tanks that focus on plant growth.
  • Filter heaters are a combination of filter and heater together. These types are designed to heat the water as it comes out of the filter and is usually not sufficient to heat the entire tank.

Do I Need a Thermometer for My Aquarium?

It is always advisable to use a thermometer in conjunction with your aquarium heater so that you can keep a close eye on the water temperature. Some aquarium heaters will come equipped with a thermometer already, and others won’t.

Many aquarium hobbyists recommend using two thermometers, perhaps one that’s digital and one that’s mercury-based, so that a variation between the two readings will be easy to see. This ensures that the water temperature is correct in the event one of the thermometers doesn’t work correctly.

How Many Watts Does My Heater Need to Be?

Choosing a thermometer with the correct wattage to heat your aquarium is vital. Too little wattage and the water temperature won’t be warm enough. Too much wattage and the water temperature may rise too high and cause devastation to your tank and its inhabitants.

The basic guidelines are between 2.5 and 5 watts per gallon of water in the tank. However, this can vary depending on how warm you need the water to be.

Final Thoughts

Building and maintaining an aquarium of beautiful tropical fish can be a great hobby, but like anything, it takes careful thought and practiced methods for it to be successful. Since you’re taking on the responsibility of caring for living creatures, it’s important to learn the correct way to properly take care of your fish and give them the best life possible.

One way to do this is by ensuring the environment in the tank is ideal for your fish. It’s important to remember that different species of fish require different habitats. When setting up a tank for the first time, it’s recommended to research the types of fish you will be including before making any purchases.

You need to make sure the fish in your tank has the right water temperature, oxygen and nitrate levels, the right lighting, and the right filtration system to thrive. You also need to make sure the fish you choose will get along. You could always seek the advice of a professional who will be more than happy to help you choose the right setup for your new tank.

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