What fish can you not put with goldfish?
You’ll want to avoid choosing tank mates that are aggressive or semi-aggressive, like African cichlids or Tiger Barbs and stick with friendly species instead. You’ll also want to avoid putting territorial fish in a tank with goldfish, even bottom-dwelling fish that usually avoid the open areas goldfish prefer.
Are goldfish toxic to other fish?
Myth #9: Goldfish Produce a Toxin Dangerous to Other Fish
Goldfish are not toxic in any way. This myth likely stems from the large amounts of ammonia these fish excrete, but all fish excrete ammonia, not only goldfish. Goldfish do tend to be messy and eat a lot.
Do goldfish need tank mates?
Some fish are only able to thrive in warmer goldfish aquariums, whereas others will be fine in a very cold goldfish aquarium. Goldfish are peaceful enough to cohabitate successfully with a wide range of tank mates, which gives you plenty of options to add to your goldfish pond or tank.