Goldie the Goldfish wants you to know that there are some roommates that aren’t the best! Truth be known, pretty much only other goldfish are good roommates. (There are many species of goldfish.) Since you pick the roommates, this article hopes to curtail misinformation and unintended mistreatment of this amazing, beautiful, and valuable animal who we love by helping you understand who does not work as a tank mate and why not.

The “room” we are talking about is an aquarium, not a goldfish bowl. This is because in a bowl, a goldfish will die before its time of ammonia poisoning from its own waste, of organ failure from the stunting of its growth because the bowl is too small and therefore the goldfish has a growth-inhibiting hormone that it releases to limit its growth in a small bowl, of hypoxia (not enough oxygen) since the bowl is too small and does not have enough surface area for oxygen exchange, or of jumping to its death since there is no lid on a bowl.

Goldfish are social and therefore should be kept in groups; but, there they will need enough space, filtration, and aeration, among other basic care factors for keeping goldfish. We’ll go into that more in-depth in another article, but for now let’s remember to not mix single tail varieties of goldfish with fancy goldfish. Young, small single tail gold fish might be o.k. for a short time - then you’ll have to give them their own aquarium before they get too big and fast and can easily injure the more delicate fancy goldfish. It’s the same situation with the common goldfish.

Goldfish work well as a community fish only when they are with other goldfish and maybe only one or two other compatible species. If you don’t abide by this rule, the unprecedented amount of goldfish waste can make other fish sick. Regarding the enormous amount of waste material produced by the goldfish - you must have extra filtration and aeration and many other species of fish cannot survive in this type of aquarium environment where there are great currents of water.

The perfect environment for goldfish also includes water that is colder than aquarium water for most fish.
The goldfish environment starts to sound increasingly hostile to most other species, too, when you become aware that goldfish get quite big and will eat almost anything - even when it’s swimming by them. They also tend to get parasites that don’t seem to be bothersome to anyone except the other fish in the tank. Goldfish can also get physically aggressive to other kinds of fish when trying to eat or mate.

It’s not just the goldfish being aggressive to other types of fish, but the other way around, too. The fancy goldfish, for example, many times have physical problems because of their delicate nature. That’s why you’ll find other fish beating up on your dear goldfish if you put them together.

So, some fish to avoid with goldfish are: Rosy Reds, White Cloud Mountain Minnows, and Hillstream Loaches (the goldfish will get larger than them and have them for a snack!); also never put betta fish with your goldfish because they require basically the opposite type of living conditions and one or the other will be a goner! Goldfish pretty much just like each other and you!