The Best Goldfish Tank Mates and their Requirements

Reasons Only Some Fish are Compatible with Goldfish

It’s important to select only suitable goldfish tank mates to avoid the problems below.

1. Temperature: Goldfish Prefer Cooler Water than Most Other  Kinds of Fish

Tropical fish (such as Cichlids, loaches, tetras and others) need to live in temperatures that would be too toasty for goldfish and carry far less dissolved oxygen.

Goldfish (slim-bodied ones anyway) prefer temps in the 65-80 degree F range with changes from season to season.

Tropicals don’t require periodic cold spells, which help goldfish to shed their excess fat. In fact, colder water may harm their health.

Of course, in a home aquarium, many times seasonal fluctuations do not occur even for goldfish not kept with tropical fish.

2. Aggression: Your Goldfish Can Get Picked on

There’s no doubt about it:

Getting picked on isn’t fun.

For goldfish, it can be very stressful.

Putting some other types of fish in with your goldfish all too often leads to bullying or injury.  Your goldfish may end up spending its days hiding in terror from its persecutor.

For example:

Many algae eaters (such as the plecostemos) are responsible for a large number of goldfish injuries on a regular basis, as their suction cup mouth can fix on the side of the goldfish and chew away at their tasty slime coat.

Want to know the worst part?

They typically do their dirty deeds when nobody is around to watch them.

This leads goldfish owners to think their fish are sick when suddenly they wake up to a large red sore on their goldy’s side.

Even the supposedly peaceful Bristlenose Pleco has been reported to attack goldfish!

Koi are notoriously overbearing towards their smaller fancy cousins and should never be housed in the same tank with them.  They also get much, much larger than goldfish and do best in ponds.

If this happens in your tank, don’t blame the bully. The fish isn’t being mean – it is just doing what it naturally does.

Right now, if you have your goldfish in with them, get them out immediately.

You may have to find another home, or start up another tank (we’ll get to that later).

3. Your Other Fish May Get Digested by Your Goldfish

It’s a fact:

A goldfish will eat any fish that fits in its mouth – if it can catch it.

So while it is still young your other fish may be okay…

… Until after another year or so, when the goldfish has doubled in size.

One day you might look in the tank and think your other fish went *poof* into thin air.

Since they do it with their own babies… they probably don’t think twice about turning their tank mate into sushi!

Slim-bodied breeds will probably turn any fish smaller than themselves into shark-bait.

Most people don’t have problems with White Clouds getting eaten by their fancies, but occasionally it can happen if the goldfish figures it out – and one by one, they’ll all disappear.

The other fish have to be fast or large enough so this can’t happen.

Bonus Reason: Goldfish Have Different Diet Requirements than other Species

It’s a fact that goldfish require a large amount of vegetable material to keep their digestive tract working correctly.

Too much of a high protein diet can lead to swim bladder troubles.

The other type of other fish you get will probably have much different nutritional requirements than your goldfish.

This brings us to the next question:

So What other Fish Do You Put with Your Goldfish?

The good news is, you don’t have to have one isolated little goldfish as the only inhabitant of your beautiful aquarium.

(That is, if it is large enough).

Goldfish are community fish and get along great with other goldfish and some other select species the majority of the time under normal circumstances.  Some people think they even form bonds with each other as lifelong friends.

There are some things to keep in mind, which are:

1. The size of the fish

It isn’t a good idea in most cases to put really small or young goldfish in with a “Shamu” sized buddy.

One will end up getting all the food, and the other one going hungry – which can lead to malnourishment.

2. The breed of the goldfish

Goldfish come in such a wide variety of shapes and body modifications.

While goldfish are usually peaceful, not all breeds are necessarily a good fit.

Some have very sensitive eye areas and may be more prone to getting picked on by more hardy companions – such as the Ryukin or Comet.

Make sure to research before even mixing different breeds of goldfish for that very reason.

For example:

Black moors do best with other fancy goldfish like fantails, Orandas, Ryukins or Bubble eyes because stronger, athletic slim-bodied fish like Common or Comets can out-compete them for food.

When in Doubt, Always Remember that Less Stress is Best!

Diversity in having different goldfish tank mates is interesting and important, no doubt.

But so is the happiness of your goldfish – and your sanity.

Get this:

Many times it’s just a bad idea to add more fish into the tank PERIOD because there just isn’t enough room to support the tank’s inhabitants.

This leads to all kinds of problems…

… Which can include having your fish feeling very stressed from overcrowding.

I think we all want the best for our pets.

But don’t lose hope!

You can always keep a separate community tank if you absolutely must have a variety of other types of tropical or saltwater fish. That way you won’t have to deal with any of the problems that come with mixing goldfish with other kinds of fish.

Here’s a tip:

Just be sure you don’t go too crazy, as too many tanks can make you stressed out if you are too busy to maintain them all. 

Whatever you do, always be sure you quarantine any new inhabitants before introducing them to your aquarium in order to avoid disease outbreak.

One method that works for many smaller species (such as keeping betta fish with goldfish) is to use a hang-on breeding box attachment for your tank.

I explain how to do that successfully.

Read More: How Betta Fish Can Live with Goldfish

Some Final Thoughts

There have been and always will be people who claim to have success mixing many other different types of goldfish tank mates than the ones mentioned here.

Granted, there are times when it does seem to work out every so often.

However:

These are the exception, NOT the rule – in my humble opinion.

Things may seem to go “swimmingly” for a while…

But sooner or later, 99% of the time you will run into trouble.

One thing is for sure:

When it comes to goldfish keeping it is always better to be safe than sorry!

The risk of injury or even death to any of your tank’s inhabitants just isn’t worth it.

You don’t want to make any fatal mistakes with your beloved pet, which is why we wrote the complete guide to goldfish care, The Truth About Goldfish.

It has all the answers you will need for keeping a thriving, harmonious, disease-free goldfish aquarium.

You can check it out here.