Complex sentence: Some tetras and barbs are compatible with angelfish, however ones that are small enough to fit in the angelfish's mouth may be eaten and generous portions of food should become habit so that the angelfish don't get hungry and turn on their tank mates.
Split into simpler sentences: Some tetras and barbs are compatible with angelfish, however ones that are small enough to fit in the mouth of the angelfish may be eaten. Generous portions of food should become habit, so that the angelfish don't get hungry and turn on their tank mates.