It's not a permanent tank, it will hold him for a month at most before I move him into one of my larger axolotl set up. Additionally, animals don't actually grow to the size of their environment, so as long as he is fed and cared for properly he will grow normally. As for the size of the tank now, it's roughly 16 square inches which is more than adequate for an axie his size (you can actually see his tail poking out from behind the left side of the bamboo). The stones are all larger than he is, and are in fact the large river stones I use in my adult axolotl environment. They are too big for my 12 inch adults to eat, so I can say with confidence this baby will not be able to ingest them. As for cleaning and filtration, I do twice weekly water exchanges and test nitrites, nitrates, pH and ammonia daily, so I am also not concerned about his water quality. I appreciate your concern, however and I'm glad that you asked these questions. I should have included the dimensions and such in the first post just in case anyone tried to duplicate it.