Yes, In fact many of the victims of the titanic were eaten by fishes
Plankton, algae. They also feed on the decaying corpses of other fish and animals in the water.
so that they could like eat more donughts
No, unless they are dead. In that case they might feed on their rotting corpses.
Whales eat krill and other fish. Fish eat other fish, depending on what type of fish it is.
There are fish that do eat them, but not ALL fish eat them.
no they eat dead fish no they eat dead fish
yes a fish can eat a fish for example many bigger fish eat bottom eaters.
No some fish eat smaller fish which eat even smaller fish
tooth fish eat people tooth fish eat people tooth fish eat people
It would depend upon the size of the fish. Small fish probably eat plankton. Larger fish eat smaller fish. Some fish eat invertebrates.
Scavengers eat anything lying around, no matter how disgusting a human might think it is.
Gangs of Pond Skaters eat backswimmers although I dont know if they attack live creatures or just dispose of corpses.