Funny you should ask, I was just searching for the same thing today. I wanted something more natural than pool filter sand for a new tank - checked out the petsmartcos and they were useless. Ended up finding some just like in that picture at an independent LFS. I would go check out any fish stores you have nearby first. Failing that, search the web? My LFS was calling it 2/16 gravel, if that helps any.