I had an acan at the bottom of my tank devour my purple bali acro at the top. My tank is 29" high. The acro was up around 23" to the top. It was about 11pm and my moonlights were on. I went to go get some snacks and looked in the tank on my way and saw a big ball of spermy stuff. Then when I took a closer look it was the acans guts eating the crap out of my acro. It was like somthing from a sci-fi flick. Gross and cool at the same time. My acro was about 8" across and gone complety at 5am. Sold the Acan! Didnt want to loose my red planet! ............so if you have any LPS in your tank you should stake out one night or setup a web cam.