There's one problem with fishing in the game. When the fish finally bites on to your rod, you will have to quickly tap or press a key (on PC) to catch the fish. Which is something you will have to do in 1 second. When server lag or connection lag is involved, sometimes less than 1 second. This makes fishing pretty annoying to do sometimes.
I believe that fishes that bite on to your rod should stay for atleast 3 or 4 seconds before they run away.