What Temperature Do Glofish Need? Do They Need A Heater?

Jan 14, 2022

What Temperature Do Glofish Need

Image Credits: Ho-Wen Chen (Creative Commons license)

There’s no one specific answer to what temperature do glofish need. That’s because there are 5 different glofish varieties made from 5 completely different species with unique sets of needs. 

While creating glofish, the scientists strategically chose the hardiest species like barbs and bettas. However, that doesn’t mean you can keep them at any temperature and expect them to do just fine. 

Water that’s too cold and water that’s too hot – both can have dire consequences and can potentially prove fatal. 

So, let’s discuss the ideal water temperature for different glofish species and what happens if the temperature isn’t right. 

What Temperature Do Glofish Need?

The temperature for glofish should fall between 60-81°F (15-27°C). So far, there are 5 glofish species, and they’re all tropical fish. Therefore, they prefer warmer water and need a heater. Ideal temperature range for glofish tetras is 60-80°F, for glofish barbs is 74-80°F, for glofish danios is 65-77°F, for glofish bettas is 78-80°F, and for glofish sharks is 75-81°F. 

What Temperature Do Glofish Tetras Need? 

Glofish tetras can sustain in temperatures ranging between 60-80°F (15-26°C). However, they’re more comfortable and active when the temperature clocks between 70-80°F (21-26°C). 

Glofish tetras actually come in two types: standard glofish tetra and long-finned glofish tetra. Both are the genetically modified versions of the black skirt tetra, also popularly known as black widow tetra. 

Glofish tetras are peaceful and amiable fish for the most part. However, since they’re also schooling fish, they need to be kept in at least a group of 6. 

If kept alone, they can get stressed and mean – resorting to nipping at the fins of other tankmates. 

15 gallons is the minimum recommended tank size for glofish tetras. 

I know glofish tetras, like any other tetra, are the poster child for fish suited for tanks as small as 1.5-2 gallons. 

And the reason I’m recommending 15 gallons is because these are schooling fish that need to be in groups. Schooling is their innate instinct, and you shouldn’t deprive them of it. 

A 15-gallon tank can comfortably house 6 of them. 

They can easily live for 3-5 years if cared for properly. 

What Temperature Do Glofish Barbs Need?

Glofish barbs thrive the best in temperatures ranging between 74-80°F (23-26°C). Like their original species, tiger barbs, these are tropical fish that like their water on the warmer side. 

Glofish barbs are best described as semi-aggressive fish. That’s because they have a thing for nipping fins. 

However, the aggression can be kept under control by and large if they’re kept in sizable numbers. 

Like neon tetras, glofish barbs are schooling fish. Therefore, you should aim to keep at least 6 of them. 

When schooling fish are kept alone, they tend to get stressed and depressed. And you definitely don’t want to wake the monster inside glofish barbs. 

Although the minimum recommended tank size for glofish barbs is 20 gallons, I strongly suggest going slightly bigger. These are incredibly active fish that would do well in tanks sized 30 gallons or above. 

And lastly, they enjoy a pretty decent lifespan if you raise them well. They can live for up to 7 years. 

What Temperature Do Glofish Danios Need?

group of glofish
Credits: Ho-Wen Chen (Creative Commons license)

Glofish danios do perfectly well in a wide range of temperatures between 65-77°F (18-25°C). Like the original zebra danios, glofish danios are tropical fish and extremely hardy. 

Glofish danios are mid to top dwelling fish known for their peaceful disposition. But they can get angry and lash out at other tank mates if kept alone or in very small groups. 

Like glofish tetras and glofish barbs, these are schooling fish. Therefore, be prepared to at least keep 5 of them together in the same tank. 

And although the minimum recommended tank size for glofish danios is 10 gallons, as always, bigger is always better. 

Since they make super active swimmers that love to dart around the tank like a flash, a long tank is preferable over a tall one. 

With good care, they can make it up to their fifth birthday! 

What Temperature Do Glofish Bettas Need? 

Bettas originally came from the rice fields and small streams of Thailand. They’re tropical fish. So, the ideal temperature for glofish bettas would fall between 78-80°F (26-28°C).

Like the original species, glofish bettas can be aloof and territorial. Therefore, it’s best to keep them alone. They don’t get lonely. In fact, they’d very much appreciate the personal space. 

While you can get away with keeping a sorority of female bettas in the same tank, there’s no chance you can house 2 males together no matter how big their tank is. 

Male bettas are even known to fight their own reflection! 

The minimum recommended tank size for a glofish betta is 2.5 gallons. But I would recommend allocating 5 gallons each to ensure comfort and enough exercise. 

As a matter of fact, small tanks are never ideal, no matter how small your fish is. Small tanks only mean one thing – small room for mistakes. 

Even the slightest error is magnified in a small tank, leading to grave outcomes. 

The average lifespan of a glofish betta is 3-5 years. But they can definitely live longer than that in a healthy environment. 

What Temperature Do Glofish Sharks Need?

Glofish sharks are used to warm water. Hence, the temperature should fall between 75-81°F (23-27°C) for these fish. And you will definitely need a heater to maintain the temperature.

Glofish sharks are genetically modified versions of the popular rainbow shark, also called the red-finned shark. What impresses me is that even with the modification and new coloration, they have retained their iconic red fins. 

Like their all-natural cousins, glofish sharks are notorious for their bad temper. Therefore, keeping more than 1 rainbow shark in the same tank is never recommended. 

They’ll fight until there’s only one gallant fish standing tall. 

Due to their highly territorial and aggressive nature, the minimum recommended tank size for a single glofish shark is 50 gallons! Yep, you read that right. 

That’s why the fact that the largest tank capacity advertised for glofish is 10 gallons baffles me. 

As I said above, the safe bet here is to keep one rainbow shark per tank. But if you insist on keeping more than 1, you will at least need a 125-gallon tank. That being said, bigger is always better. 

With proper care and diet, glofish sharks can lead a long life. They’re known to live up to 8 years! 

Recommended Readings!

Pregnant Glofish? You Might Land In Legal Trouble!

What Fish Can Live With Glofish? Complete List For All Species!

What Do Glofish Sharks Eat? Can They Smell Blood?

Do Glofish Need A Heater? 

Yes, absolutely! Glofish need a heater! In fact, a heater is indispensable equipment when setting up a glofish tank. Installing a sturdy heater is essential to mimic and maintain the temperature of their native habitats at all times.

Here’s what the heater capacity looks like for different glofish species 

Glofish Species Tank Size Heater Capacity 
Glofish Tetras15 Gallons100 Watts
Glofish Barbs30 Gallons150 Watts
Glofish Danios10 Gallons50 Watts
Glofish Bettas5 Gallons50 Watts
Glofish Sharks 50 Gallons200 Watts 

And here’s our handpicked recommendations for different capacity heaters. Feel free to check out! 

Brand Heater Capacity
Tetra Submersible Heater With Electronic Thermostat 50 Watts (more options available)
Hydor Submersible Glass Aquarium Heater 100 Watts (more options available)
Aqueon Pro Adjustable Heater150 Watts
Vivosun Aquarium Heater200 Watts (more options available)

What Happens If The Water Is Too Hot For Glofish? 

Glofish are tropical fish that prefer warm water. But what happens if the water gets too hot? It can be downright fatal if you don’t intervene at the right time. 

Hot water loses oxygen a lot faster than cold water. And even though your glofish may be able to tolerate the warmth for a certain time, they can quickly suffocate to death due to lack of oxygen. 

Hot, deoxygenated water moves to the top. So, cold and relatively oxygenated water settles at the bottom. 

Therefore, your fish will resort to laying at the bottom and making the best use of available oxygen. 

A few signs of suffocation in fish are: 

  • Sluggishness 
  • Loss of buoyancy 
  • Convulsions 
  • Whirling 
  • Flashing
  • Twisting 
  • Lack of appetite

Suffocation isn’t the only repercussion of hot water. It will also unnaturally increase your fish’s metabolism – forcing it to produce more waste, leading to a spike in ammonia-producing bacteria. 

This once again depletes the tank’s oxygen levels. And you already know what happens when the oxygen levels decline. 

And if you think the tank’s water is too hot, don’t take any steps to lower the temperature drastically. Glofish don’t react well to sudden changes. 

What you can do is blow cool air over the tank using a fan or an air conditioner. Don’t use ice packs or ice cubes as they can lower the temperature dramatically. 

And to infuse much-needed oxygen into the water, you can use an air pump. 

Here’s one that I use for my tanks. 

What Happens If The Water Is Too Cold For Glofish?

Keeping glofish in cold water can be just as deadly as keeping them in hot water, if not more. 

Glofish are cold-blooded creatures. They rely on their environment to regulate and maintain ideal body temperature. 

So, if the water’s too cold, it will negatively impact the fish’s metabolism. On top of that, it also hinders the fish’s oxygen intake process. These two effects, combined or single-handedly, will make your fish lethargic and tired. 

And it will resort to the bottom of the tank to rest. 

If you don’t increase the temperature gradually in time, cold water will eventually wear down the fish’s immunity and make it susceptible to several pathogens that reside in the tank. 

To increase the temperature slowly but steadily, you can use an in-tank heater or light source. If there’s no electricity, placing a hot water bottle in the tank can help too.

Frequently Asked Questions 

2 glofish danios
Credit: Ho-Wen Chen (Creative Commons license)

Do Glofish Need A Filter?

Yes, this is a no-brainer. Glofish most definitely need a filter. And don’t cut corners when buying one. The water parameters for glofish should look like this:

  • Ammonia 0 PPM
  • Nitrite 0 PPM
  • Nitrite Below 20 PPM 

And to maintain these parameters, you will need the support of a sturdy, reliable filter. 

Do Glofish Need An Air Pump?

Although an air pump isn’t as indispensable as a heater or a filter, your glofish will surely benefit from one. A well-oxygenated tank, directly and indirectly, helps ensure your glofish leads a happy and healthy life. 

Do Glofish Need Light At Night? 

As magnificent as glofish look under fluorescent lights, sorry, but no, they don’t need light at night. Glofish are diurnal creatures that remain active during the daytime and need a good sleep at night. 

Like most tropical freshwater species, glofish should receive about 12 hours of light and 12 hours of darkness. 

Final Words: What Temperature Do Glofish Need?

All 5 glofish species were made by genetically modifying tropical fish like barbs and bettas. Therefore, all of them prefer a temperature on the warmer side. 

The ideal temperature should fall somewhere between 60-81°F (15-27°C).

And you’d want to invest in a reliable, sturdy heater for that. Don’t pinch pennies. 

If the temperature gets too low, it can lead to a host of health complications and even potentially cause death.

Recommended Readings!

How Big Do Glofish Sharks Get? Are They Even Sharks?

How Big Do Glofish Danios Get? Is Your Danio Stunted?

How Many Glofish Tetras In A 10-Gallon Tank? There’s Bad News!

rohit gurung author at urbanfishkeeping

About Rohit Gurung

My never-ending love and fascination with Aquascaping started when I received a red-eared turtle for my 10th birthday.

Apart from researching and writing, I spend hours gazing at my 3 turtles. And yeah, I bask alongside them too.