I found the best way to make money on Gaia without investing a lot of cash. The way to get money is a very fishy one. You get throw aquarium tanks.

Do you know the minigame Booty Grab?
Just tap some tanks from other Gaians and maybe you have a bit luck to get the Booty Grab bonus game. There are dedicated threads of it in the forums. Check them out and tap them like crazy.

It really pays off. I almost made around 30k gold today with Booty Grab.

How about you tap my tank too? Just do it ;D