I made the same mistake, Now a dozen years later i have some huge clowns. Mine toss around the big pebbles to dig. Years back when I had too many clowns I sent some to a friend to add to his group. I few weeks later I was informed that my clowns had taught his to toss pebbles as well.
Fist are pretty amazing and will usually adapt to their surroundings as long as they are within reason.
Take corys, in nature they live and feed in all sorts of waters and on various substrates from sand to bedrock and including leaf litter, gravel and even sharp gravel.
More important than the choice of substrate is keeping them in groups and in bigger tanks.