Well my 2 Porks started in a 20 as I remember then went to a 45 then a 58 then a 150 then a 125. Get the idea. I think a 29 would work with a baby for about a year. Now my Dogface in 3 years grew from a baby to a 15 incher and lives in a 58 by itself (should have a bigger tank but it is doing ok for now and seems to have stopped growing longer just grows fatter. As I have said Porks due to their personality really deserve a tank of their own with a couple of friends to big for them to have for dinner (I love that line from the first Hannibal movie, which by the way is what I named my baby starts and stripes puffer, my newest Puffer friend). Dogs tho when really big in my estimation need to be alone period they tend to be much meaner to tank buddies then Porks, and they have the teeth to make their point.