glass not so great because it doesnt allow very good air exchange and there is usually a pretty good gap in the back still. I would recommend getting some eggcrate from a hardware store like lowes, menards, home depot or some people get picture frame material and stretch a screen in it for smaller holes. Any hole that it can fit through it could find eventually. yes I believe the snowflakes are the less aggressive eels and one of the better looking ones in my opinion. Dont get me wrong there is some risk in this but it can be done. I would also recommend always feeding it with a feeding stick and do not use live foods. Buy the eel small but not to small (around 8-9") and obvioulsy it would be best to get more mature fish, a 3" clown will be better than a 1". It can be done.