on a recommendation, for my new puffers, it was suggested to mix in some crushed oyster shells into some repashy, when mixing it up... I found a small package of pretty finely crushed oyster shells, since my puffers are still babies... curious if any other fish would benefit from the oyster shells in the food ( they are actually there to help keep the beak on puffers from getting too big ) or if the oyster shells would do harm to other fish, & I'd be best keeping that as puffer only food... if so, I might mix up half a package regular, & half a package with the shells... thoughts???... unless there could be harm, I figured the worst, other fish would eat around the oyster shells, & they would just end up as part of the substrate... & could increase water hardness over time... but since I'm now using RO, it just may add some minerals to the neutral water???