Bubbles in your tank are most commonly caused by agitation in your tank when you are filling it with water, and agitation is not necessarily harmful to your tank. ... The fish could also be causing bubbles to appear if they are in need of a water change, making the bubbles as they breathe air on the surface of the water.

Why are there bubbles in my fish tank?

When filling a new aquarium, a lot of agitation is created causing bubbles or a slight foam to form at the water's surface. ... Cold water can hold more oxygen than warmer water, so when this cold water enters the aquarium and mixes with the warm water, oxygen is released forming those little bubbles you are seeing.

Are bubbles good for a fish tank?

An aquarium bubbler, also called an air stone, adds beneficial bubbles to the aquarium's water. When these bubbles rise to the surface, they help the oxidation of water and improve the living conditions of fish, plants and other living creatures in the fish tank.