Hindu mythology tells us that Lord Vishnu’s first incarnation was that of a fish: Matsya Avatar. Mahavishnu took on this avatar at the end of the Satyuga when there was a great flood. Mahavishnu, in his Matsya Avatar, saved humanity and the Vedas from being destroyed in the flood. There are temples dedicated to Matsya Avatar one each in Tamilnadu, Andhra Pradesh and Gujarat. Matsya avatar marks the beginning of the Dashavatars of Lord Vishnu. The annual festival of Matsya Jayanti falls on Chaitra Shukla Paksha Tritya ( March-April).
Our shastras mention that evil forces do not enter a house when there is an Agni burning or any creature like a fish watching.
It is believed that fish absorb negative energy and their movement in the water contributes to positive energy.
Aquariums have a very good effect if placed in the living room in the North, East or North-East corner. The living room is the place where people visiting may bring in negative energy. This is why it is recommended to place an aquarium in this area.