Goldfish are traditional pets that are often bought for kids. Many of these beautiful fish end up living in isolation in their tank, apparently very happily.
But does your goldfish really need a tank mate? The simple answer to that question is yes!
In this guide, we take a closer look at the humble goldfish and explain why these fish need company to thrive.
Does Your Goldfish Need A Tank Mate?
Goldfish (Carassius auratus) have been kept as ornamental pet fish for over 2000 years. There are now over 200 species of goldfish, some of which are pretty rare. But breeders originally produced all of these fish by crossbreeding wild Prussian carp. In nature, carp tend to live in societal groups, and modern goldfish have that same desire for company.
Ideally, you should keep goldfish in groups. However, these social fish can grow quite large, up to 12 inches in the case of Comets and other long-bodied goldfish, so you need a large tank or pond to accommodate them. As a general rule of thumb, you must allow one gallon of water per inch of fish, and you need a very efficient filtration system to cope with the amount of waste that goldfish produce and keep your tank clean.
There are other species of fish that can do well with goldfish. But what works and what doesn’t work depends to some extent on the type of goldfish you have, the nature of your setup, and the size of your community tank.
What Are The Basic Types Of Goldfish?
There are two main types of goldfish:
- Single tail
The type of fish you own is the most important thing to consider when picking a suitable tank mate.
If you keep a single tail, long-bodied goldfish, your choice of tank mates is somewhat limited. These larger goldfish are fast swimmers and are best suited to life in a pond with other goldfish of the same type or with Koi carp.
On the other hand, Fancy goldfish are generally smaller than their single tail cousins, reaching a maximum size of six to eight inches in length when fully grown. Fancies are also much slower, less agile swimmers, and some of the bubble eye varieties have poor eyesight that can cause problems with feeding.
Although you can keep fancy goldfish in a pond, they do fine in a large aquarium with an efficient filtration system. Also, fancy goldfish tend to prefer a slightly higher water temperature than their long-bodied counterparts. So, that means you can often introduce some tropical fish species to your fancy goldfish if you choose your tank mates carefully.
Evaluate Your Setup
Before adding different species to your goldfish tank, you need to evaluate whether the conditions are suitable for them.
Since goldfish produce a lot of waste, you need a high-quality filtration system to keep the water clean and free from toxins. However, the flow must be buffered, as fancy goldfish don’t appreciate a strong current.
Fancy goldfish are cold-water fish that need cooler temperatures between 68° and 74° F. The water pH should be between 7.0 and 8.4. These are hardy fish that do very well, provided that you keep the water clean.
However, that ideal temperature range could be too cool for most tropical fish species, and warmer than that is too warm for goldfish.
Unsuitable Tank Mates For Goldfish
Now, let’s take a look at what fish species do not make suitable goldfish tank mates.
Goldfish are voracious eaters and will eat pretty much anything that they can fit in their mouths, including smaller fish such as minnows.
It’s not a good idea to keep shrimp with goldfish, as the goldfish will usually regard the invertebrates as lunch, chase, and eat them. It’s a similar story with aquatic snails. Larger size mollusks that are too big to be swallowed are fine in a goldfish tank. However, it’s best to avoid species such as Nerites and others with cone-shaped shells that could injure your goldfish if swallowed.
If you have long-bodied goldfish, you should avoid putting them with slower swimmers that might be outcompeted for food. Slow-swimming fancy goldfish don’t mix well with swift, agile swimmers for the same reason.
Also, fancy goldfish develop long, flowing fins as they mature. Goldfish fins can be extremely tempting for some nippy fish species.
Goldfish are peaceful fish. They are completely non-aggressive types that are not territorial or defensive. If anything, these fish tend to hang out together, foraging for food and exploring their environment.
So, you don’t want to include any territorial or aggressive tank mates with goldfish. That can cause a great deal of stress for the goldfish, resulting in stress and health problems.
What Are The Best Tank Mates For Goldfish?
Single Tail Goldfish
Let’s find you the best potential tank mate for your single-tail goldfish. Check out this list of candidates that can live with goldfish in peace.
Koi are a species of ornamental carp that come in a vast range of colors and patterns. These fish are similar in build to single tail goldfish, although they typically grow to be much larger fish.
Koi and single tail goldfish enjoy similar water conditions and diet, and the two species do well when kept together in a pond setting.
Common goldfish are good beginner fish often sold cheaply in stores as feeder fish.
These fish do best in a pond, and adult fish can quickly grow to 12 inches or more in length. However, you can keep one single specimen in a 20-gallon tank, adding a further 10 to 15 gallons to that for every additional goldfish that you add.
The Comet is a fast swimmer. This active fish can reach 10 to 12 inches in length. Comets have wide, spread tails and come in a variety of color morphs.
The beautiful Shubunkin is also sometimes called the Calico goldfish, although they have different types of scales.
Shubunkins typically have multicolored patches of color, including blue, red, orange, gold, white, black, bronze, and purple.
Tank Mates For Fancy Goldfish
Fancy goldfish come in many different varieties, and their requirements tend to vary between types. However, generally, these colorful fish prefer warmer water and a very low flow rate, which gives you lots of options for companions.
Platy fish are small tropical fish that come in a wide variety of colors and patterns, and you can even get a form with a long, pointed tail. These fish grow up to around 3 inches in length, making them too big for a goldfish to attempt to eat.
You need to keep Platies in groups of at least five, and these livebearers will breed readily, although your goldfish will most likely eat the fry.
The Longfin Rosy barb is a beautiful fish that can grow to around 6 inches in length, preferring cooler water and a roomy tank of 30 gallons or more. These barbs tend to hang around the middle area of the tank in a large school and won’t bother your goldfish.
Checkered barbs are excellent community fish that are more peaceful than other barb species and should be a good companion fish for your Fancy goldfish. These attractive tropical fish can reach 2 inches long and need to be kept in schools of eight or more.
Although smaller minnow species are a source of food for a hungry goldfish, Giant danios grow up to 4 inches in length, and they are fast swimmers, too.
These schooling fish do best in groups of five or more and prefer a comfortable temperature range of 72° to 75°F.
Murray River Rainbow Fish
For an unusual addition to your goldfish tank, check out the beautiful Murray River Rainbow Fish!
These gorgeous fish reach 4 inches in length and enjoy living in groups of up to six individuals. In the wild environment of the River Murray in Australia, the fish live in temperatures of 70° to 78°F. Interestingly, cooler water seems to bring out the Rainbow Fish’s best coloration.
The Scissortail Rasbora is a shy, peaceful schooling fish compatible with Fancy goldfish.
These beautiful silver and black fish can grow to reach 6 inches in length, preferring to swim in schools in open areas of the water column. However, they often like to chill out around lush planting and tank decorations when they need shelter. Ideally, you want a group of at least six Scissortails, preferably more if you have plenty of space in your tank.
Scissortails enjoy temperatures between 72° to 77°F and share the same dietary requirements as goldfish, making them excellent goldfish companions.
Zebra danios are attractive black-and-white striped schooling fish that are commonly kept as community fish. These fish tolerate a wide range of tank conditions and can live happily in temperatures from 65° to 77°F.
These schooling fish prefer to live in groups of six or more and can grow to reach 3 inches long, making them too big for an adult goldfish to eat. Danios are fast swimmers that prefer a slow current, making them the ideal companion for goldfish.
Also, even if there are a few casualties while the danios are still growing, their low cost makes that less of a financial blow to the hobbyist.
White Cloud Mountain Minnows
White Cloud Mountain Minnows can be a good option for a Fancy goldfish tank. These pretty little fish grow to 1.5 to 2 inches long and love to school together.
Although White Cloud minnows can be eaten by goldfish, they are swift swimmers and can usually escape curious Fancy goldfish without too much difficulty. The trick is to provide plenty of lush planting and caves where the minnows can hide if they need to.
There are a few varieties of minnows to choose from, but we recommend that you avoid the longfin type, as their long fins slow them down, increasing the chance of their being caught.
Although goldfish like to explore the whole tank, they tend to spend most of their time in the middle to upper areas of the water column. So, you can keep a few bottom-dwellers that won’t encroach on the goldfishes’ swimming space.
Also, many bottom-dwelling species are beneficial to the hobbyist as a tank cleaning crew. Therefore, including a few in your goldfish tank is a win-win!
Dojo loaches are also known as Weather loaches.
These fish are fascinating creatures that are highly sensitive to changes in barometric pressure. If your Weather loaches begin to get agitated, you can be sure that a storm is on its way!
These fish should be kept in groups of at least three with a minimum tank size of 55 gallons or more. Your tank must have a tightly fitting lid with no openings, as these strange little loaches can climb, and they will escape if given a chance!
Corydoras catfish belong to a group of over 100 different species of small, scavenging catfish that are extremely popular with aquarists.
These little fish are extremely hardy, easy to care for, peaceful, and they can live for up to seven years. Corys come in different sizes, depending on the species, ranging from 1 to 3 inches long.
We don’t recommend keeping Corys in single-tail goldfish tanks as there is a danger that very large goldfish might eat the Corys. However, a small school of six or seven of one of the larger Cory species would most likely be fine in a Fancy goldfish tank.
Bristlenose plecos are amazing fish that work extremely well in a goldfish tank, feeding on excess food and food scraps that have fallen to the bottom. These bottom-living fish get along fine with both single-tail and Fancy goldfish, too.
Bristlenoses can grow to reach 5 inches long and develop thick, whiskery tentacles around their snouts once they reach adulthood. These armored catfish are peaceful, chilled-out dudes that spend most of their time keeping algae levels down, resting on wood or the viewing panes, or scavenging for scraps of food.
These plecos can tolerate a wide range of water temperatures from 60° to 80°F.
Reticulated Hillstream loaches can be kept in ponds or fish tanks and might work well with single-tail and Fancy goldfish. These shy scavengers generally grow to around 3 inches long, spending most of their time hiding underneath wood, rocks, and among plants, foraging for uneaten food.
These loaches prefer cooler conditions with water temperatures of 68° to 75°F. Their secretive nature makes it easy to keep loaches with goldfish, as you won’t see them very often. You do need a tank over 55 gallons, as these can be territorial fish.
The Hoplo catfish is a very peaceful species that reaches 5 to 6 inches long when fully grown. There are several different species of Hoplo catfish, including the Flag Tail, Spotted, and Tail Bar Hoplo.
These charming catfish have long whiskers that they use to search for food. These catfish are active during the daytime, unlike the Bristlenose and Rubbernose plecos that are nocturnal, so you will get to see them in action.
It can be a challenge when it comes to choosing the ideal tank mate for your goldfish. The most suitable companions for your fish will depend on what type of goldfish you have, your tank size, and the setup.
Generally, the best tank mates for goldfish are simply goldfish of a similar shape and size. However, there are plenty of other viable options, as you can see from our guide!
Do you have unusual tank mates that do well in your goldfish aquarium? We’d love to hear about them! Please share your experience with us in the comments box below.