Well, something else to prove that what you hear isn’t always true. I use a
Python which gets deep into the gravel. I changed to the sand because everyone told me it was a choking hazard. The goldies didn’t like it though. I honestly think they would have jumped out of the tank if I had not had a lid. They were swimming up and down the sides of the tank looking for an exit. Even splashed! They do pick gravel up but so far, always spit it out. They absolutely hated the sand and were stressing out. I never saw them act like that before. I have been using gravel in my goldfish tanks since I was a child and have never had one choke. I decided I had better chances with the gravel than the sand that they hated. Out of 6 tanks, my 2 goldfish ones are the only ones with gravel. I wish I had left it in all of them though. Not being able to get the bottom clean is nasty to me. My doctors office has sand and there is always stuff around the plants and rocks in it too. I hover over the sand but more gets stirred than sucked up. I just don’t like sand!