You have to check Fewer clicks.

It's very important. You have to click once on the bottom of the aquarium, to feed nsails and other things, and also spin your fishes right. In the other way they will make a circle and not feed well.

Now you just have to minimalise your game.
For me it's Tab + Shift

Now you can read books about fishing, breeding fishes and other stuff.

Congratulation!
You finish it!
I hope you enjoy my quide!