Hmmm.. prob about 10 inches... he wasnt even full grown... had put a female carpintis in with him and they were flirting alot.. one day he had pretty nipped up fins! So I added a devider... he sank to the bottom just staring at her through the devider like a sad puppy dog... me and the girlfriend thought it was kind of cute paying no mind to it... 2 days later he died... must have got stressed out by the devider? It was very odd... sometimes everything seems ok... but if your pet shows any type of stress it's best to acknowledge it quickly... fish... especially hybrids are very sensitive to streas