no experience with kelberi or orino but my mono grew roughly 2-3 inches in the last 1.5-2 months i have him. Roughly 4-5 inches now. I have mine in a 72 gallon and it seems like he still has plenty of swimming room so should be enough for another few months till i have to upgrade. If you plan on upgrading soon (within 6 months) then don't see the problem with having one or two in the 60 gallon.