I've never heard of a ID shark getting over 8-9" in length. I know of someone that had a pair for 6 years (from the time he got them) and they only got about 8-8.5" long. I haven't seen him since he moved about a year ago. SO I don't know how big they are now. But they hadn't grown any after about 3.5 yrs. They are awesome. And I agree that they need a lot bigger tank. But that particular fish shouldn't get any bigger then 9". But for sure give them to a good home.