nah what I meant was I thought that there was a big risk of them swallowing too much sand and dieing? If this isn't the case I might swap out substrates in my goldfish tank also
Sand is actually better for goldies for that reason. Sand passes harmlessly through their system if swallowed, but gravel (depending on size) could be come lodged in their throats. There is a lot of debate over this topic though; Gravel still works just fine.