Actually, depending on the dimensions of the tank that you have, and yer waste removal efforts, and only like one other tank mate, u can keep a snowflake eel in that tank. It just needs to be sealed well, have a good protein skimmer, and enough rock for it to hide in. They really dont need to move much, it just depends onw ater volume to waste ratio. And uh, ive never heard of a snowflake eel killing a lion. Some other eels, yea, but snowflakes are peaceful. They have sort of bumpier teeth thatn the "fanged" eels. It will figure out that the lion is poisonous anyways...