DoOdADs: Mini Whale

I just got a fish tank, but nothin’ lives there yet.
First I’ll put some water in, an’ then I’ll be all set.
My mom said “get a turtle”, my dad said “get a snail”,
And both of those are good ideas, but I think I’d like a whale.
Nothing big or fancy - just a little one will do.
I’ll feed him mini marshmallows and maybe call him Stu.
He’ll like it in my fish tank, swimming to and fro.
He’ll come up to the surface, then take a breath and blow.
Stu will be a great friend an’ I’ll teach him to play ball.
And I’ll keep him here forever, as long as he stays small.