1. Ideal Temperature Ranges for Tropical Fish

• Most tropical fish: 24–27°C (75–81°F)

• Discus and some South American species: 28–30°C (82–86°F)

• Betta fish: 25–28°C (77–82°F)

• Hardy species like guppies, mollies, and platies: 24–26°C (75–79°F)

• If the aquarium houses multiple species, a compromise temperature suitable for all should be chosen.

1. Types of Heaters and Their Selection

• Internal heaters: The most common type, glass-tube models placed inside the aquarium.

• External (in-line) heaters: Connected to the filtration line, saving space inside the tank.

• Substrate heaters: Special systems installed under the substrate, ideal for planted aquariums.

• Models with automatic thermostats are the most reliable for maintaining stable temperatures.

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1. Things to Consider When Choosing a Heater

• Select a heater with wattage suitable for the tank’s volume (general rule: 1 watt per liter).

• For example: 50W for a 50-liter tank, 100W for 100 liters.

• The heater glass should be thick and resistant to breakage.

• Fully submersible models are preferable.

• Models with digital or manual temperature displays provide ease of use.

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1. How to Monitor Temperature

• Always keep a thermometer in the aquarium.

• Check the temperature daily with digital or adhesive thermometers.

• Test heater settings against nighttime temperature drops.

• Be especially careful with sensitive species when it comes to sudden temperature fluctuations.

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1. Common Mistakes in Heater Use

• Plugging in or unplugging the heater while it’s out of the water (may cause damage).

• Setting the temperature too high (can shock the fish).

• Placing the heater too close to the bottom or surface of the tank.

• Not using a thermometer and missing dangerous fluctuations.

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Conclusion
The correct temperature setting for tropical aquarium fish directly impacts their quality of life and immune systems. Using a safe, high-quality heater to maintain stable water temperatures helps protect your fish from disease and supports stress-free growth. With the right equipment and daily monitoring, you can create a healthy and stable aquarium environment.