I have a 75 gallon right now with one common goldfish. Please keep in mind I got this fish from someone who had it in a turtle tank that was meant to get eaten by the turtle. This fish unfortunately got stunted at around 6 inches (from being in the turtle tank so long) and hasn't grown much in the 2 and a half years I have had it. I've never had any issues with the fish besides some fin rot when I first got him. I would like to know if its possible to add another fish to this tank? I probably wouldn't add another common so any suggestions would be great. I would defiantly add another filter to it since I only have one with around 450 gallons per hr. I know thats low but I haven't been able to afford one so I must just go with doing frequent water changes. I'm not looking to add another fish right away, but I would just like to know if it's a future option. I really want what's best for my fish.