They go up for air several times a day, and like to burrow into the gravel and live under the substrate. Rubber eels are dumber than most tropical fish, and have considerable difficulty dealing with food that moves. They have only moderate difficulty with food that doesn't move. They are extremely confused by other bottom-feeders. We think they are cute, and it's great to have one who insists on being hand-fed and will curl up in your hand and wrap itself around your fingers.
Smarter animals run from large mammals in the water.