I have 2 CB and they both have grown moderately. The bigger one that I got about a year ago in about a month. Has grown about 3-4". I got it at about 4" so It's about 7-8". I got another one about a month ago and it has grown an inch since then. I got it at about 3" so It's about 4" now, however I haven't really measured in a couple of weeks only eyeballed sizes. He however had Bichir worms so I had to treat him and not feed a lot his first week. He is also in a grow out with some larger polys. The larger one is also in with about 20 more polys ranging from 4"-16". IMO if they were both separated they would probably grow a little faster, because they both have HUGE appetites especially the one in the big tank. He is one of the first and last ones eating. I also haven't measured him in a couple months, but have been able to use the size of other polys to estimate. If anything they are both probably bigger than what I am saying, but I don't take mine out to measure. I'd think that they'd be almost in the middle, not super slow and not super fast maybe leaning towards slower.