Like other electrical equipment, aquarium heaters are also safe and unsafe, depending on several factors. Therefore, one needs to take proper precautions and safety measures both before and after installation. Buying quality products is always better in the long run. Don't choose a heater just because it is cheap. Right wattage is equally essential. Excessive heat can cause severe health problems to the fish and can even harm the aquarium. In rare cases, aquariums have been known to burst due to this problem. Read the manual and understand it fully before installing the heater. Positioning and placing them correctly is essential. Check regularly to see if it is working well and if you notice any sign of damage, replace it immediately. Even a small faulty part in the heater can trigger major problems.