i'd never put a baby corn in a tank that large. they won't find their water etc from what i've heard. i keep mine in a smaller (more like a 5 gallon tank) tub.

and yes... they definitely need a water dish!

i use aspen cause my corns LOVE to burrow under their substrate.

one word of caution: baby corns are escape artists!!! if there is even the smallest gap between the lid and container they are in... they will be gone!!!