they can but use them just as a treat every once in a while, like feeder goldfish (comets) they are very high in fat content so dont make it a staple in their diet. mine usually likes sinking pellets better because, like you, i have two oscars and they usually eat the floating ones before the knife can get any. it does get up there and eat with them sometimes. i use tetramin tropical crisps and sinking pellets. the crisps are great because they sink slowly so my knife swallows them up on the way down.