Yes, I've heard of that happening especially with goldfish. Kept in a 20 litre for 2 years, moved to a much bigger tank then does, loads of stories like that hopefully he will do ok, he survived the move to my tank ok, and was much calmer so hopefully he will be even happier in a tank twice the size
The person who got him is going to keep in touch so I will keep you updated
The person who got him is going to keep in touch so I will keep you updated