equipment

Heater Stuck Off

Heater failure causing temperature drop

Symptoms

Measure actual temperature with a reliable thermometer — do not trust the heater dial.
Check power: plug, outlet, indicator light, and thermostat setting.
Have a spare heater of the correct size ready as backup.

Do not leave the tank unheated overnight hoping it recovers — temperature drops steadily.
Do not reuse a heater with a cracked casing or scorch marks.

This guide is informational and does not replace professional veterinary advice. If fish are severely ill, consult a veterinarian.