Sad. Put a beautiful new colony of striped acans into our 29g clownfish tank. It is full of BTAs plus some shrooms and a bit of cabbage leather. We recently added a couple tubs of fragged shrooms also. So, I thought it was fine for 4 days but maybe wasn't observing carefully, then saw two nems had moved and some shrooms were closed up. Acan was nearly dead and polluting the tank with stringy goo. : ( Removed acan, did water change and hoping things look good Monday. So do the BTAs exude some chemicals or expel nematocysts or something that killed the acan? Could have been unhealthy coral, too. I never considered there could be a problem, but that tank has a big volume of nems. Should no corals go in that tank?