I'm currently working on a 29-gallon tank with a 29-gallon sump/refugium. I'm estimating it will have 50 gallons of water volume. Right now I'm thinking about putting two telescope butterfly goldfish in the display. I don't think water quality will be a problem, I'm using 3.5 gallons of k3 fluidized media and a refugium in the sump to suck up nitrates and plan on bi-weekly water changes. My main concern is space, do you think 2 butterflies will have enough room in a 29 or should I just keep one?