Eheim Jager 125W Aquarium Heater Fully Submersible

The Eheim Jager 125W Aquarium Heater brings precision heating to medium aquariums up to about 40 gallons. Fully submersible with the trusted adjustable TruTemp dial (65–93°F / 18–34°C), shatterproof glass, and automatic dry-run shutoff, it keeps your water beautifully stable day and night.

Why aquarists trust the Jager

• 125 watts of reliable heat: Sized for aquariums around 26–40 gallons
• Precise TruTemp dial: Adjustable from 65–93°F (18–34°C) with a calibratable dial for spot-on accuracy
• Fully submersible: Mount it horizontally or vertically, freshwater or saltwater
• Shatterproof glass: Lab-grade, durable construction
• Thermo Safety Control: Automatic shutoff protects against accidental dry running

Setup & safety tips

• Place the heater near good water flow (by a filter outlet) so heat spreads evenly.
• After plugging in or before unplugging, wait ~15 minutes for the glass to adjust to water temperature.
• Always verify the actual tank temperature with a separate thermometer.

Not sure on sizing? Comparing sizes? See the 100W for smaller tanks or the 150W for larger ones. Browse all aquarium heaters or the full Eheim equipment lineup.

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