goldfish - tropical fish community tank

Question
Lee

I have been out of the aquarium hobby for about 8 years. Recently I set up my old 55 gal tank intending to establish either a community tank or a Cichlid tank (oscars) but I "adopted" 5 goldfish from my parents outdoor pond. I believe they are comets. A salesperson at the local store claims the ammonia output of the goldfish will kill any tropicals I put in the tank. Is this true ? I run a 150gph power filter and an undergravel. I have the tank operating at 76deg fahrenheit. So can I put other fish in the tank and if so what types. Thank you in advance for your assistance. Kevin

Answer
yes goldfish of any kind have a higher ammonia output than other fish, it may not kill them but goldfish and tropical fish do not do well together with one wanting heated water and the other doing better in cooler water, I would not put them together.