You can also use particles within a game environment to make realistic looking elements such as fire or, in the case below, bubbles. Unity does have some default particles that can have its material changed to show a different colour however using sprites of elements can have a more realistic look. To do this you can add the sprite sheet to the particles material option and set the offset (depending on how many images are used within the sprite sheet) This will then animate the particles, switching in between each of the sprite images to change their look.

There are also many other options offered within the particle animation such as changing colour and opacity overtime, setting the range, height and scale and much more!

I decided not to use these particle animation in my scene however as I had already animated bubbled within Maya and was happy with the way that this looked.