Whether guppies need a heater mainly depends on the water temperature of the breeding environment. Here is a comprehensive analysis:
Temperature Requirements
Guppies are tropical fish, with the optimal water temperature ranging from 22 to 26°C.
The minimum tolerable temperature is 16°C, but long-term exposure to temperatures below 18°C can lead to reduced appetite and weakened immunity.
Criteria for Determining Heater Need
Cases Requiring a Heater:
When the water temperature drops below 20°C in winter.
If the fish tank is placed in an area with large temperature fluctuations (e.g., near a window or air conditioner).
During the breeding period or when nursing sick fish.
Cases Where a Heater May Not Be Needed:
In tropical/subtropical regions where the room temperature remains above 20°C year-round.
When the water temperature stabilizes between 24 and 28°C in summer.
Heater Usage Recommendations
Choose a thermostatic heating rod with a power matching the tank size, and monitor the temperature with a thermometer.
Ensure the heater is fully submerged during installation and avoid contact with the tank walls.
Maintain a water temperature of 24–28°C for optimal conditions in winter.
Risks of Not Using a Heater
Prone to diseases like white spot disease and fin rot.
Significantly reduced breeding success rate.
Faded body color and decreased activity.
Conclusion: Decide based on the actual environmental temperature. Heaters are strongly recommended for winter in temperate regions. If opting not to use a heater, ensure the water temperature always stays above 18°C and closely observe the fish’s condition.