betta plus bowl conditioner for goldfish??

As long as the conditioner will get rid of ammonia, and chlorine (chloramines when combined) as well as heavy metals then you should be alright or rather you goldfish should be alright. The big thing is to make sure that you have a large enough tank for your goldfish, they should have at least 20 gallons per fish and more would be even better since they can grow quite large. At a small size they may be alright for a while but after they grow (and they continue to grow through out their lives). But you should think about getting them into a larger tank than most people who think that a ten gallon tank is large enough for ten goldfish. That is cruel treatment for your pet to keep them in too small a tank and also they need partial water changes on a weekly interval (15 to 25% weekly is not too much but you should not have to change much more unless you overfeed. On feeding you should not feed more than the fish will eat in a couple of minutes and also make sure to give the fish a variety of foods (would you like to eat the same food all of the time?).