yea, I found out that even small opens can lead to disaster, I had an acrylic cover on an open tank of which i used two acrylic sheets and i had a one inch opening in the middle of the tank where the two sheets would match up if pushed together, and on top of the acrylic i put my light on which left only a small one inch by one inh opening in the middle of the tank, the whole evening i kept hearing "bump" "bump" until i finally heard a splash and found my bichir making a getaway on the ground 4 feet below, they are smarter then they appear to be
