Depends on what kind you're talking here. However all the newts (Fire-belly, Eastern Newt and others) that I know of need at least 10 gallons of water per newt, they get much too large to be held in less than one gallon. And then there is the climbing factor, they're generally fantastic climbers and will be out and about if you're thinking about trying to market your Patented waterfall thingy with them.