How do fish communicate with each other?

I actually found this interesting and went for a search. I found some of these websites about goldfish intelligence and that they had training kits to train your fish. I remember that I had a betta that was very attached to me, and would seem to make certain movements whenever I would come near the tank. he would look like an eager, happy puppy. I am not sure, I will search some more, very interesting. So far, it seems it's by movements.

They talk fish! Dolphins can understand and communicate so much but they are classified as mammals. I think fish use sound and it is amazing how much you can hear underwater. I have a couple of gold fish and they seem very attentive to what is going on in the room.

Yes, something like that and the release of pheromones. The also use body language and some even change colors to communicate their wants and feelings.

I think yes, they communicate by sound waves. Like whales, they are communicating by sound waves. Some other species is by their colors though. But as far as I know, they produces sound which can even travel far away to communicate.