Rescue Comet Goldfish advice

[kerrburns]

Last week I rescued a Comet who is approximately 1.5 years old and had been kept in a 5 gallon tank its whole life thus far. He's approximately 8 inches long. Although I've had Fancys before, this is my first Comet. He is now in a new 55 gallon and is MUCH happier. My question is do I get him a tank mate? He's said to have been alone his whole life. I know a 55 gal isnt big enough for 2 comets. Alot of compatible non-goldfish are schooling fish, and I'm not sure if I should be adding more to take up his space? Do you think he's fully grown at this point? I know poor thing is probably stunted Any advice is appreciated!!

[Mother of fish]

I wouldn't add anymore tank mates. I am assuming he will grow more with a good diet and proper space. He is only 1.5 years old yet. If you are in a warm enough climate, he would honestly do best in a pond and can grow much bigger, then you could definitely get a good sized school of fancies to go with him.