Eheim Jager 25W Submersible Heater

Small tank, big reliability. The Eheim Jager 25W Submersible Aquarium Heater brings the legendary German-engineered precision of the Jager line to nano and desktop aquariums. It holds a rock-steady temperature so your fish, shrimp, and plants stay comfortable — all from a compact, shatterproof package you can fully submerge.

The 25W is a great fit for small setups; as a general guideline, figure roughly 5 watts per gallon for a 5–7 gallon tank in a normal room.

Why aquarists trust the Jager

• 25 watts of reliable heat: Ideal for small nano and desktop aquariums (~5–7 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? Stepping up a size? Check the 50W and 75W Jager heaters. Browse all aquarium heaters or the full Eheim equipment lineup.

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