Eheim Jagger Thermostat Stainless Steel Aquarium Heater, 100 Watts

Living up to the company's reputation, the heater is efficient, durable and long-lasting. The holders, cord and instruction manual are also world class. There is a thermostat dial at the top, where you can set the temperature to a particular point. Note that you'll also need another thermometer separately to be sure of the accuracy. You'll need to adjust the settings per your second thermometer, which you can buy at affordable prices separately. One of the best features about such a high quality heater is that the temperature variation is very smooth, thereby not stressing out the poor fish. Important note - aquariums should NOT be set at a higher temperature (beyond 28-29C) because it raises the metabolism of the fish, thereby decreasing its life span. After a day or two of observation, I removed this heater because the city in which I live is usually warm. If I have an aquarium in Ooty or Bangalore, I might consider using this heater to maintain the temperature at around 27. If the surrounding temperature is beyond 27, you can turn this off.

Excellent product, great quality.

Very costly, available at much lesser price in online aquarium stores. Good heater but costly in amazon. The cost of 300watt is Rs 3995.