You could keep them in the thirty while they'll still small. If I remember right the gost glass catfish get to be 2 to three inches. Double check me on it, but for some time that should be enough. I keep my 7-8 inch knifefish with Buenos Aires tetra's and young Bosemani's and everything's fine. These fish are active schoolers (I think the catfish like to be kept in groups also) and all about 1.5 inches.
Cool! if this helps.
Cool! if this helps.