I got a huge bag of aquarium gravel with the Betta kit I bought online. I don't need the rest and its just taking up space in the cupboard. Can I feed it as grit to my chickens?
More often than not aquarium gravel is coated with clear epoxy resin or colored in some way and I don't think I would use it if not 100% sure it is not.
Granite is used for packaged grit because it is hard and has somewhat sharp edges. Aquarium gravel has NO sharp edges so it is not a good substitute unless you're going to crush it first.
Just a note: I was worried about my chickens because there was a lot of glass on this property when I moved here. But, I found out that chickens can eat the glass and it comes out in their poop. I pick up anything big enough to see but they still get the little stuff.