my goldfish is getting really lazy,it sits at bottm of tank and only gets excited when he sees food,he with his friend and in new tank,plus had two more baby fish put in.what's wrong with him.he used to be so lively

Tell us about your setup. How big is it? How big is the fish? Do you have a filter and aeration? How often and how much water do you change? What additives do you use? Do you use dechlorinator and aquarium salt? What do you feed him? Have you checked the pH, ammonia, and nitrite lately? Often, fish lethargy is attributable to water quality issues but it can also indicate illness. I doubt he's lazy but fancy goldfish tend to rest more. What kind of goldfish is he? I hope he's okay!