I’m not sure what kind of goldfish these are. My wife got them at a fair years ago and is attached to them. When it got a little colder out I got a heater for the tank since we turn the heat down to 60 in the house. I set the heater to 77 since thats what I read was good for the pleco. The goldfish seemed very lathargic when the water got cooler with lower temperatures during the day. They have been in a heated tank for a while now and seem to be doing just fine. Will 2 goldfish really mess up the ph balance of a 60 gallon tank that much that it will make in uninhabitable for other fish?