When it comes to maintaining a successful aquarium, there are a lot of parameters to keep in mind. One of the most important is temperature.
Believe it or not, the temperature of a tank is so important that a few degrees in the wrong direction can have devastating effects on the health of the plants and animals in the tank.
If your fish aren’t acting right or your plants are dying, the temperature is one of the first things you should check.
Finding the right temperature for fish tanks depends on a few different factors. Let’s take a closer look at what your fish need to thrive.
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What Temperature Should a Fish Tank be?
How warm a fish tank should depend on the type of aquarium you have and the variety of fish you’re keeping. So, there isn’t a straightforward answer. To determine the ideal temperature for your tank, here are some key things to consider.
Temperature for Freshwater Fish Tank
Freshwater aquariums should be kept anywhere between 72 to 82 degrees F (22-28°C). A good number to aim for is 77 degrees F (25°C), right in the middle of the range.
Of course, this will depend on the type of fish you stock your aquarium with. Some freshwater aquarium fish, like goldfish, prefer cooler water while others, like gobies, prefer water that’s a little warmer. Make sure you research the proper temperature for each kind of fish you add to your tank.
Temperature for Saltwater Fish Tank
Finding the right temperature for a saltwater tank isn’t very straightforward either. Saltwater fish come from oceans all over the world and their environments vary slightly from one to the next.
It’s always a good idea to base the water temperature of your tank on the preferences of the fish you put in it. Generally, 79 degrees F (26°C) is a nice medium but, again, check to see what your particular fish prefer.
Temperature for Reef Tank
Reef tank temperatures vary depending on the type of coral you have. (As you might have noticed, this is true for all tanks, no matter what is living in them).
In nature, most coral reefs have an average temperature of between 82 and 84 degrees F (28-29°C). Although it’s commonly recommended that reef tanks be kept at a temperature of 74 to 77 degrees F (23-25°C), this might be a little too cold. Aim for a range of 75 to 79 degrees F (24-26°C).
Temperature for Planted Aquarium
What plants you’re adding to the tank determines the best temperature but plants are a little more forgiving than coral and fish. The range for a planted tank can be anywhere from 70 to 80 degrees F (21-27°C).
There are a lot of reasons why this wide temperature range is great. For one thing, it makes planted tanks slightly easier to care for. It also means that you can choose from a wider range of fish for the tank because you can change the temperate as needed to make the fish and plants happy.
Ideal Temperature for Some of Aquarium Fish
The ideal temperature for aquarium fish is determined by considering their natural environment. There’s a little bit of wiggle room because the fish you buy from the pet store have all been raised in aquariums, not in their natural habitat.
Temperature for Betta Fish
Bettas are native to the area around the Mekong and Chao Phraya Rivers. They make their homes in the streams, ditches, and rice paddies in countries like Cambodia, Malaysia, Vietnam, and Thailand where the average temperature is 83 degrees F (28°C).
Bettas live in shallow water so they’re used to higher temperatures. A range of 76 to 81 degrees F (24-27°C) is ideal. Aim for maintaining a steady 79 or 80 degrees F (26-27°C).
Temperature for Goldfish
Goldfish naturally come from waters around China but they are found in just about every state in the US due to people releasing their pets or from having been used as bait. They’re a very hardy species and can survive in the wild in temperatures ranging from 40 to 78 degrees F (4-26°C).
But you don’t want your pet goldfish to merely survive, you want it to thrive. For that, goldfish require temperatures between 65 and 72 degrees F (18-22°C). This is significantly colder than a lot of other species so be careful if adding a goldfish to a community tank.
Temperature for Guppies
The natural habitat for guppies is the warm, clear waters surrounding Trinidad and Tobago in the Caribbean and the waters surrounding Guyana, Venezuela, and Brazil in South America.
Guppies adapt to different temperatures better than most aquarium fish. They can survive in environments as cold as 55 degrees F (13°C) but, again, surviving is not the same as thriving. The ideal temperature for your guppies is between 72 and 79 degrees F (22-26°C).
Temperature for Molly Fish
Mollies are a small tropical fish from South and Central America. They can live in both freshwater and saltwater so they’re pretty adaptable.
Ideally, their water temperature should be between 77 and 82 degrees F (25-28°C). They can handle lower temperatures but this is the range where they’re happiest.
Temperature for Platy Fish
Platys are fun, colorful little fish native to Central and South America. Their natural environment is in water that ranges between 65 and 78 degrees F (18-26°C).
In an aquarium setting, platys should be kept in an aquarium with a water temperature in the higher end of the range, between 75 and 78 degrees F (24-26°C).
Temperature for Tetra Fish
Neon tetras are a favorite for fish tanks because they’re small, inexpensive, and very easy to care for. They’re naturally found in various places around the world, including Brazil, Colombia, and Peru throughout the Amazon River.
The best temperature range for tetras is between 72 and 78 degrees F (22-26°C). Once the water reaches 80 degrees F (27°C) or higher, their metabolism starts to work too quickly and they become very stressed.
Temperature for Clownfish
Natural habitats for the clownfish are the warm waters of the Pacific and Indian Oceans. Because they prefer to live around sea anemones, you’ll also find them in the area between Japan and the Great Barrier Reef northwest of Australia.
In an aquarium, clownfish do best in a temperature range of 72 to 78 degrees F (22-26°C).
Temperature for Gobies
There are many types of gobies. It’s one of the largest fish families in the world with more than 2,000 different varieties.
If you add gobies to your aquarium, make sure to research the specific type choose to make sure you’re using the right tank parameters.
For most types of gobies, a tank temperature of between 75 and 82 degrees F (24-28°C) is a good range. Some can tolerate water as warm as 86 degrees F (30°C) but 80 degrees F (27°C) is a safe temperature to aim for.
Temperature for Discus Fish
Discus fish are found in small creeks, lakes, pools, and streams of the Amazon but not in the river itself. Since they live in shallow water in a hot climate, they prefer water that is a little warmer than some of the other fish we looked at so far.
The ideal temperature range for a discus is 82 to 86 degrees F (28-30°C) , though some varieties prefer water as warm as 90 degrees F (32°C).
Temperature for Killifish
There are more than 1200 species of killifish. They all have slightly different requirements when it comes to tank parameters, including temperature.
Killifish are found all over the world. They like brackish water in North and South America and can be found spanning the distance from Ontario to Argentina. You can also find them in southern Europe, Africa, Asia, and the Middle East.
Because there are so many different types of killifish, it’s best to research the variety you get to make sure they’re in the right environment. Generally, a temperature range of 72 to 75 degrees F (22-24°C) is ideal.
Temperature for Rainbow Fish
The natural habitat for rainbow fish is in the streams, lakes, rivers, and swamps of Papua New Guinea, Indonesia, and Australia.
While rainbow fish can survive in water as cool as 72 degrees F (22°C), they prefer their habitat a little warmer. To help them thrive, aim for between 74 and 78 degrees F (23-26°C).
Temperature for Catfish
There are a few different kinds of aquarium catfish, including corydoras, plecos, Colombian sharks, and red tail catfish.
A safe temperature range for catfish is between 72 and 82 degrees F (22-28°C). That said it’s important to do some research about the specific variety you choose to make sure this is the best range.
Temperature for Angelfish
Freshwater angelfish are found in the Amazon River basin in Brazil, Colombia, and Peru. There are a few different types of angelfish though most prefer the same tank temperature: between 75 and 84 degrees F (24-29°C).
This is a little warmer than most of the other fish we looked at. Be careful when planning a community tank if you’re planning to introduce angelfish. They may not do well in the same temperature that other fish thrive in.
Temperature for Oscar Fish
Oscars are a member of the cichlid family and are native to Brazil, Ecuador, Peru, Colombia, and Frech Guiana and flourish in the Amazon River basin. There are also feral populations in China, northern Australia, and around the state of Florida.
These fish are very sensitive to temperature changes and do not do well in water that is too cold. Ideally, they should live in a tank with a temperature between 75 and 80 degrees F (24-27°C).
Temperature for Gourami Fish
Gouramis are native to southern and eastern Asia, particularly from the areas around Pakistan, Thailand, Vietnam, China, and even as far north as Japan and Korea.
There are a lot of different types of gouramis but they all prefer the same water temperature and do best in a tank that’s between 75 and 80 degrees F (24-27°C).
How to Keep Aquarium Temperature Constant?
The easiest way to keep an aquarium at a constant temperature is to use a heater with a thermostat. They are often included in aquarium starter kits and available for purchase separately.
All you have to do is place the thermometer in the water. Make sure you follow the instructions carefully. Most thermometers have a minimum waterline that has to be covered for it to work correctly.
After the heater is installed, set the temperature and make sure the heater is turned on. Most will have a light that indicates when it’s working. The thermostat in the heater turns it off and on to maintain the set temperature.
There are other heaters, too. For smaller tanks of 10 gallons or less, simple heaters shaped like flat discs or triangles are enough to get the job done. Remember, the larger the tank, the bigger the thermometer.
You should allow the water to reach the correct temperature before adding any fish to the tank. Some fish are very sensitive to temperature changes and can suffer from significant stress when raising the temperature a few degrees over a short period of time.
Also, be sure to place your aquarium somewhere where it doesn’t get a lot of sun exposure. Direct sunlight during part of the day can raise the temperature which can cause unexpected complications.
Maintaining the right water temperature is one of the most important things you can do to make sure your fish, coral, and plants stay happy and healthy.
The most important thing to remember when planning your tank is to research the fish you plan to add. While we provided you with some general guidelines, a lot of fish have hundreds of varieties or more which may have different requirements.
Choose a temperature that makes everything in your tank happy for the best results. That means that you might not be able to keep certain fish together but, in the end, it’s better to have one fish in the ideal environment than two that aren’t.