Trouble having my fish swim

Hello, I'd really appreciate some advice on this. I am trying to animate a barracuda type fish. The issue is that I can sort of visualize the fish's fins moving back and forth but when it comes to actually animating, it seems to be a much more difficult task. What I have so far looks like he is swimming in some sort of octopus like motion instead of in and out. some advice or help is welcomed.