Heaters and Chillers

Temperature is a crucial factor for the well-being of aquatic life. Most aquarium fish are tropical species, meaning they come from warm waters and require a heater to thrive. However, some aquatic creatures, like axolotls, need cooler water than typical room temperature. Understanding the temperature needs of your tank is essential to providing a healthy environment for your fish.

Water's thermodynamic properties prevent fish from thermoregulating. Simply put, cold water makes fish cold, and they cannot warm themselves up. This is similar to how humans struggle to function in cold water, even if the temperature is only 70°F (21°C).

Just because your Betta fish survived for years without a heater doesn’t mean it thrived. Imagine being thrown into a walk-in fridge without a jacket—you’d survive, but it wouldn’t be pleasant. Fish exposed to improper temperatures are more susceptible to stress, weakened immune systems, and disease. Even a slight temperature shift can be detrimental. Think of it like this: a 2°F (1°C) rise in body temperature in humans equates to a fever, and a 3°F (2°C) drop could result in hypothermia.

For tropical fish, a heater is not optional; it’s essential. If you're unwilling to invest in a heater, you might want to reconsider keeping fish. A pet deserves the best care possible, and providing the right temperature is fundamental to their health and happiness.

When a Heater Isn’t Necessary

Not all aquarium species require a heater. Goldfish, for example, are not tropical fish and do not need one. However, fancy goldfish (such as orandas, fantails, and black moors) may benefit from a heater, as they prefer slightly warmer water. On the other hand, creatures like axolotls need cooler water, so a chiller (the opposite of a heater) will be required to maintain the proper temperature.

Heater Selection

To choose the right heater, a general guideline is 5 watts of power per gallon of water. For example, a 50W heater is ideal for a 10-gallon tank, and a 200W heater is perfect for a 40-gallon tank. Always research the temperature needs of your specific aquarium inhabitants to ensure they have the best possible environment.