I use them as accents to show off the color of the Betta. When I had my 1st Betta in a big glass bowl I found them so much easier to rinse off when I was doing a cleaning. I got a plastic strainer/colander kind of thing they couldn't slip through so I could put them under the water and swish them around alot to get all of the nasty junk out. (Then I just dedicated it to just using for that bowl) I found a bunch of them at the nothing over a $1 dollar store in the plastic plant dept. The price difference between there and the pet store was unreal--like $5. The worst difference was the dust factor at the dollar store but heck, they rinse off easy enough! I got a bunch for the filtered planted tank I just set up too to add to the top of the substrate. Frankly, I think they're better for longer finned Bettas as they are sooo smoooth to glide over versus a bunch of rocks! My boss at my last job had a bowl with this marble grouping of colors that were in her multi-colored guy including pink!! That's what got me onto using the colors to accentuate the fish's colors. Good luck!