I've never heard a Rubberlip bothering a GF,but I guess never say never. Laurie's right though,They love a veried diet.I know they're known to love algae,but you should see my guys tearing into some semi-cooked Spinach Leaves,Zucchinnii,Squash,Collard Greens,etc. They have grown so much since I added the Snails,and started feeding all the veggies. As for the algae wafer's ,mine will eat them,but they don't always like the particular Brand I 've had.I actually bought a few different ones before I got it right for them.