Thanks for all your comments. Here are some comments of mine to some specific problems that were mentioned.
Camera: Yes the camera didn't worked out, as it was intended. It runs ahead with the players speed-vector and whenever you change your direction (especially when you jump and drop down afterwards) the camera rushes around and doesn't show you, what's going on above. Needs some tweaking.
The controls: There are only few buttons but I should have mentioned them somewhere (just forgot about it). You can move "left" and "right", with ether "a" and "d" or "left" and "right" arrowkey, and jump hitting "space". You can use your jump after each second to swim upward or damp your fall, since there is no need to be grounded. I will add this to the itch.io discription.
Feedback on eating: It is missing simply because I ran out of time. It was planned to play a simple eating animation whenever you grab some food. It was not planed to add any sort of food progress feedback except your own grows, but it is a good point I will think about.
Graphical bug when dying: Yes I am aware of it and I will try to fix it.
One last thing: Sometimes the fishes get to close to the ground just due to pure RNG. This can lead to undeserved death, so the fish movement needs and will get some tweaking. But I will wait until the end of the votings before I update my game again.
Thanks again to @narve, @zorg, @rabbittortoise, @killerkun, @toonteamj, @huminaboz and @kosmo for your comments and constructive critique.