Glowlight Tetras are a staple tropical fish, possessing many desirable traits of the ideal peaceful community fish.
But are they able to live in temperate or cold water aquariums? Can Glowlight Tetras be kept without the use of an aquarium heater? And what happens if the water gets too cold?
Find out by reading this article;
Can Glowlight Tetras live in cold water?
Glowlight Tetras cannot survive in cold water, they are tropical fish and need to be kept warm in captivity if they are to live healthy lives.
If kept in water that stays below 20C / 68F consistently, they can be subject to various health issues which can lead to death in extreme cases.
Glowlight Tetras are tropical fish, and should only be kept in a tropical tank.
Can Glowlight Tetras live in a tank without a heater?
If your aquarium is situated in an area that stays warm (above 23C / 73F) year round, then you may not need a heater to keep Glowlights.
However, if this is not the case, then you will need a heater if you are to provide the best care and welfare for your fish.
Heaters are very important in tropical aquariums, not only for keeping the tank up to temp, but also as a tool to control the environment and respond to change.
Increasing or decreasing the temperature as a response to behaviour, disease, feeding and time of year allows you to monitor and manipulate the perfect environment for your fish, which is why we always recommend them, even if you live in a hot climate.
How long can Glowlight Tetras survive without a heater?
As mentioned, if the outside temperature is high enough, your Glowlight Tetras may go a long time without a heater, they may live their entire lives without one.
However, there may be a period where things get unexpectedly cold, and if the tank drops in temperature significantly, they may struggle to survive longer than a few days in the absence of a heater.
It is all dependent on how drastic the temperature difference is, but as a general rule, we would suggest that you avoid allowing your fish to become exposed to temperatures lower than 20C / 68F for any longer than 48 hours.
Why do Glowlight Tetras need a heater?
Glowlights need a heater because they are tropical fish, and have evolved in an environment that consistently remains above 20C / 68F.
Because of this, they lack the adaptations that allow them to enter a state of torpor, or adjust their bodies to live in water that frequently drops below 15C / 59F.
Without a heater, you may not be able to provide your Tetras with the right habitat, and they can develop various health issues as a result of the stress that cold water puts on their bodies.
What temperature should a Glowlight Tetra tank be?
Glowlight Tetras typically like to stay anywhere from 24C / 75F to 28C / 82F.
They can go outside of this range by a couple of degrees, but if you want your fish to do well, then you really need to be keeping them within this range.
When adding them to a community, you should be keeping them with fish that require similar water parameters and temperature ranges.
We like to keep our Glowlights at around 26C / 79F, as it seems to be where they are most comfortable and healthy.
For breeding purposes, you may keep them warmer, but be aware that they will need feeding much more often, perhaps twice daily, as their metabolic rate will be increased.
Types of aquarium heaters for Glowlight Tetra tanks
There are a number of ways to keep your Glowlight Tetra tank warm.
Aquarium heaters are the easiest and most reliable method of providing warmth in a safe and controlled manner.
More specifically, glass aquarium heaters, which are the most commonly available form of heating equipment today.
These heaters are great, as they are designed to be incorporated into all different types of aquariums, large and small, coming in all different sizes to fit the literage of your tank.
They are very easy to install, and can be placed either within the main display, or in a sump filter, so long as they are fully submerged.
Choosing the right size glass heater is easy, look at the literage of your tank, and try to get a heater which matches by looking at the wattage.
For example, if you have a 200 litre aquarium, then you want to get a 200 watt heater, or something as close as possible.
However, your tank may be so large that a glass heater does not do the job.
Your tank may have a sump filter that adds an additional 100 litres, or the tank may be situated in an area that gets very cold at night.
In this case, it is best to use a Titanium heater.
Titanium heaters work much the same as glass heaters, but are much more powerful and come in much higher wattages, allowing you to keep your huge 800 litre display tank at the right temperature.
FAQs about heating X tanks
How do you test the water temperature in a Glowlight Tetra tank?
How you test for the temperature in your Glowlight Tetra tank is really down to you, there are multiple methods you could adopt using different tools.
Not all thermometers are accurate however, and while something like thermometer tape may be cheap and easy to stick on the tank and forget about, it does not always give the most pinpoint reading.
For this reason we like to use digital thermometers since they are some of the most accurate methods of testing the temperature of your aquarium.
Thermometers with a submersible LCD screen work great because they can be easily stuck to the front of the tank, where they display the temperature on a clear heads up display at all times, allowing you to respond to change as soon as it happens.
Do Glowlight Tetra fry need a heater?
Glowlight Tetras are highly vulnerable in their early developing stages, and the fry often lack the reserves and fortitude to deal with cold temperatures.
It is important when raising fry that the environment is kept very stable, so use of a heater is almost always a requirement if you want the maximum survival rate.
Without one, they may be subject to rapid temperature fluctuations that could shock and kill them.
What happens to Glowlight Tetras if the water is too cold?
Glowlight Tetras depend on the temperature of their environment to control their core body temperature.
This temperature has to be within a specific range in order for their bodies to function correctly and perform constant homeostasis, which is to maintain balance in the body.
Once the temperature drops below this range, the fish begin to undergo changes and will start to slow down their normal bodily functions in order to preserve energy.
Coldwater fish are able to enter hibernation when the water becomes too cold, and can preserve themselves for long periods of time during winter by becoming torpid.
Glowlight Tetras however, are not adapted to do this and if exposed to cold temperatures for too long will become vulnerable to disease, digestion issues and organ damage.
If over exposed to very cold temperatures for a long period of time, they can die.
What happens to Glowlight Tetras if the water is too warm?
When going over the preferred temperature range, Glowlight Tetras will do the opposite, and will actually speed up their bodily processes, increasing their metabolism and activity levels dramatically.
By a couple of degrees this may seem harmless at first, but long term they may suffer from rapid weight loss, high stress, oxygen deprivation, and increased aggression.
If the temperature continues to increase, the Tetras may suffer from organ damage, and will eventually die from heat stress unless they can cool down.