Aquarium HeatersA quality heater is necessary if you intend to maintain a successful tropical freshwater, marine fish or reef system. Temperature fluctuations often go unnoticed by aquarists and can cause stress to fish and corals. Most heaters include a built-in thermostat to select the optimal temperature for your aquarium.
Because fish are cold-blooded animals, they adapt the temperature of the surrounding water. Thus, if the water is cold, the fish will feel cold, too. In seas, lakes, rivers, etc., the water is naturally regulated so fish can liv...ONLY$47.99