It’s not unusual for someone to get their start in the fish keeping hobby by purchasing a single goldfish, and it’s not long afterwards, that most people start considering getting a friend for their goldfish. And who wouldn’t want to give a goldfish a companion? After all, they tend to look lonely in their fish tanks, and who could say no to those sad eyes?
But the truth is, goldfish are perfectly happy being on their own, and it’s often far better for the fish to be kept individually, than in groups. Especially, since most goldfish are kept in substandard and cramped conditions, and any additional fish would only make matters worse.
A pair of common goldfish need at least a 55 gallon (208 liter) aquarium, and even that is on the small side. And the more fish that are added, the larger the minimum tank size becomes. Most people simply can’t reasonably house multiple goldfish – or even a single goldfish, with the aquarium they have.
But if a person is set on keeping goldfish with another fish – and they have the space for it – there are certain fish that may work. It’s very important to note that when adding new fish to an aquarium, there should always be backup plan in place, in case aggression issues arise.
Goldfish Tank Mates
Goldfish – If you ask anyone experienced in the hobby what’s the best fish to keep with goldfish, they will invariably tell you other goldfish. Because of their unique requirements – cool water, high oxygenation, and massive tank size – they tend to usually only be kept with others of their species.
And goldfish should only ever be kept with similar breeds of goldfish. Fancy goldfish are often bullied by larger goldfish like comets and shubunkin, and will have trouble competing for food. Never mind the disaster it would be to keep malformed goldfish like bubble eyes with anything but other bubble eyes. So it’s usually best to stick with goldfish only aquariums.
Dojo/Weather Loaches – If a person is dead set on keeping another species of fish with goldfish, Dojo loaches are almost always the best choice. Not only do they prefer cooler temperatures like goldfish, they also tend to get along famously with them. Of all the fish that can be kept with goldfish, these ones are the least problematic.
The only possible issue that may arise is that adult goldfish will often try to consume juvenile dojo loaches. But this is true of any smaller fish, and as long as the dojo loaches are at least two inches long, they tend to be safe in goldfish tanks.
Rosy Red Minnows/Fathead Minnows – These are usually only known as the lowly feeder fish crammed into tanks at the local fish store. But those filthy and crowded tanks, hide one of the most interesting fish in the hobby. And since they are native to the cool waters of North America, they do extremely well in an unheated goldfish tank.
The problem arises from the fact that they can be very aggressive at times. This is especially true during spawning. Rosy red minnows are one of the few fish outside of cichlids that display parental care, and they will attack any fish that comes near their nest. This often results in goldfish with nipped fins, although the damage is rarely severe. But it still makes it somewhat unsuitable for a goldfish tank – although many people have reported success with them.
White Cloud Mountain Minnows – These fish would be perfect for keeping with goldfish if it wasn’t for their small size. They prefer cool waters like goldfish, and are almost completely peaceful. They are also a stunning fish to keep in any aquarium, and used to be referred to as the poor man’s neon tetra (back when neons used to cost a king’s ransom).
But their small size makes life dangerous for them in any tank containing adult goldfish. While they will do extremely well with juvenile goldfish, there is a significant risk they will be eaten by a large goldfish. So, the fact that some may be lost to predation needs to be considered before they are added to a goldfish tank.
Zebra Danios – These are one of the go to fish to keep with goldfish, and they are a hardy and interesting staple of the aquarium hobby. They thrive in cool temperatures, and when kept in groups of at least six, they rarely direct their aggression towards other fish in their tank (although some fin nipping is still possible.)
However, they share a similar problem with white cloud mountain minnows. While they are not as small, they could still end up being consumed by larger goldfish. Of course, due to their speed and agility, this is really only a problem with full-grown common or comet goldfish.
Snails – Snails tend to be hit and miss, and their success in a goldfish tank really depends on the temperature that the tank is kept at. Most snails in the hobby require tropical temperatures, and won’t do very well in an unheated goldfish tank.
This is especially true of apple snails, which are commonly recommended to be kept with goldfish. Not only are unheated goldfish tank temperatures usually too low for them, but they are often targeted by goldfish, who will constantly tear pieces off of the snail.
But there are some attractive snails that will thrive in a goldfish aquarium, and these include Japanese trapdoor snails and Ramshorn snails. Pond snails will also thrive, but they are neither attractive, nor really desired by most aquarists. Malaysian trumpet snails are another option, though they tend to not do as well in cool water.
It should be noted, that most goldfish will attempt to eat snails, and it’s almost inevitable some will be lost. So that should always be taken into consideration before adding snails to a goldfish aquarium.
Native Fish – In recent years, more and more people have begun to keep North American native fish. While many tend to make African cichlids look docile, there may be some fish that will do well with goldfish in their tanks.
Some people have reported success keeping red shiners, stone rollers, madtoms and dace with goldfish. However, these are far from proven, and anyone attempting this should be prepared to immediately remove the fish if aggression problems arise.
The only fish I have tried were tadpole madtoms, and they worked extremely well with goldfish. But anyone attempting to keep these catfish should be wary of the spines containing venom when handling them.