I may have received some bad info when I purchased my Sailfin Tang. I just read they can grow up to 15 inches. I’ve had her about a year and a half and she’s about 4-5 inches right now in a 125 tank. The next biggest in the tank would be a Squareback Anthias. Should I try to give her back or give away? I don’t want an unhealthy tank environment for her.