I use a whisper on my goldie tank and have never had a problem with the intake being to strong for them. Is the tank crowded? Do the fish exhibit any other signs of illness (usually this is the only reason fish get sucked into an intake, they are too weak to fight against the current).
I guess if the fish are just getting fed to something, an injured tail isn't all that important....but you might want to make sure there isn't any illness in the tank, i'd imagine feeding sick fish probably isn't a great idea.