Abstract: An airtight, open topped receptacle of transparent material totally immersed in inverted position in the water of an aquarium in spaced relation to the side walls of the latter. The lower periphery of the receptacle is spaced above the bottom of the aquarium to allow newts to pass freely therebetween. An air supply feed line supplies air into the receptacle so that an air bubble chamber is established in the latter. An aquarium bottom cover is heaped to extend into the air bubble chamber. For newt training purposes, an optional closure structure is provided for temporarily preventing movement of the newts out of the receptacle.