Self-standing fish tank thermometer

A self-standing aquarium thermometer includes an impermeable self-standing housing disposed within an aquarium containing a predetermined volume of water, the self-standing housing has a lower cavity for receiving a weighting element, which has a predetermined weight for overcoming a floating force of the self-standing housing ensuring the self-standing housing downwardly sunk into a bottom of the aquarium, a thermometer unit received within the self-standing housing in an air-tight manner, the temperature display unit includes a temperature sensor having a sensor probe exposed into the aquarium for monitoring a temperature of the, a display screen for indicating the temperature, so that when such thermometer is disposed with the aquarium, the temperature of the water would be easily viewed through a glass wall of the aquarium.