If you’re wondering “Do I need a heater for my fish tank?” the answer to that will depend entirely on what types of fish you have and what’s the average temperature of your fish tank when you’re not using a heater.
Like land animals, different types of fish need different temperatures to stay healthy. Unlike most land animals fish are usually incredibly susceptive to temperature changes. And since they can’t migrate to different waters when they are kept in a tank, even a slight variation in the temperature can mean game over for your fish.
So, the short answer to the question is that you’ll need a heater for some fish and you won’t need a heater for others.
Fish that don’t need a heater
Do goldfish need a heater? Do betta fish need a heater? Here are 10 of the most popular types of coldwater fish that can live in most tanks without needing a heater:
- Fancy goldfish (Carassius auratus)
- Barb (Barbus tetrazona)
- Guppy (Poecilia reticulata)
- Hillstream loach (Balitoridae)
- Weather loach (Misgurnus anguillicaudatus)
- Cherry shrimp (Neocaridina davidi)
- Paradise fish (Macropodus opercularis)
- Croaking tetra (Mimagoniates inequalis)
- White Cloud Mountain Minnow (Tanichthys albonubes)
- Zebra Danio (Danio rerio)
The reasons you typically wouldn’t need a heater for any of these fish is that they can both live well at lower room temperatures and can survive some minimal temperature fluctuations.
However, most other fish types such as the betta fish are extremely sensitive to temperature fluctuations and require very specific warm temperatures to survive. In the case of the betta fish, you’ll need to maintain a constant temperature of 78-80°F (25-27°C).
They can still remain healthy in a wider 76-82°F diapason but if you let the temperature drop anywhere below 74°F or rise above 85°F you’ll see a rapid decline in their health.
How to keep a fish tank warm without a heater?
Depending on where you live and where in your home you position your fish tank it’s possible to keep the temperature of the fish tank high and stable enough even without a separate fish tank heater.
Even if the temperatures in your home are generally high enough, however, it’s still smart to always keep e thermometer inside the fish tank and to look for any temperature fluctuations.
When it comes to how to heat a fish tank without a heater, there are several things to consider:
- You can slow down the rate at which temperature is dropping by using insulation materials such as papers and blankets.
- You can add hot water to the aquarium with a bucket but you’ll need to measure the quantity and temperature precisely as to not raise the overall temperature too much.
- You can move the aquarium to another heater you have in your home so that the fish tank remains warm.
- Aquarium lights give off heat so they can help maintain the temperature as well.
All in all, having a separate fish tank heater is usually just the best option if you want to keep your fish alive and healthy.
