Smoothing out animation (Check out video)

If you look at the video my fish look way too stiff. How can I make it super smooth. I don’t know if you can understand what I want. First look my video
my animation

I want to make my fish move as smoothly as the second video.

Do i need more keyframes? less keyframes? any ideas will help


Your fish need to curve in almost an S shape to get a more natural movement. At the moment the whole body is stiff and just the tail moves.

Yeah, I know but i was referring to how the movements seem to snap back and forth. I have it on key/interpolation mode/ bezier but still has that snapping not super smooth like I am trying to get


Its your tail fin that is too stiff. The tail tip needs to be really flexible. It needs to behaving like a streamer when they are not really flipping tail to push water at extreme stroke position:

Yeah, but I am starting to get it.