Does your single goldfish look forlorn, bored or just plain lonely all by himself (or herself)?

It may not be “all in your head.”

Over the years, I’ve been asked by countless goldfish keepers the probing question…

“Should I get my goldfish a friend?”

My opinion used to be that it didn’t really matter one way or the other – that goldfish do just fine by themselves.

(And in some unusual cases I think that still holds true.)

But the more I learn about goldfish, the more I feel like it is possible for a goldfish to get lonely when it’s kept as the solitary inhabitant of the aquarium.

And here’s why.

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Goldfish are Schooling Creatures by Nature

large goldfish scramble for food

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Have you ever seen a big pond full of a dozen or more goldfish and watched them swim around?

If so, you probably noticed they all stayed together and swim in the same direction.

When one starts straying off from the group, it either shortly returns to the others – or the others start following with it.

But no matter what:

They will always stay together all day as they do their thing – aka look for food.

This behavior is called “schooling.”

The reason?

So are carp (granddaddy to the goldfish), which are almost always found in schools in the wild (source).

A “lone goldfish” just isn’t the norm.

If so, something is usually wrong with it (such as sickness or injury).

This means their natural inclination is to live in groups, like many other kinds of aquarium fish.

Schooling protects fish from getting eaten by predators and serves other social uses.


Boredom is a real issue we need to combat when keeping fish in captivity.

There are solutions for this.

And one way of busting boredom for your fish is for them to have at least one buddy.

That way they’re not all by themselves all day long.

Will one goldfish be lonely?

Let’s face it:

Solitary confinement is just no fun.

Which brings me to my next point…

What Kind of Friends are Best for Goldfish?

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Some people mix fancy goldfish with slim-bodied fish like Commons or Comets.


It seems the closer your fish are in body type, the better.

“The “oddity effect” posits that any shoal member that stands out in appearance will be preferentially targeted by predators. This may explain why fish prefer to shoal with individuals that resemble themselves. The oddity effect thus tends to homogenize shoals.” (Source)

So goldfish apparently prefer to hang out with those that are most like them.

There are other concerns about mixing fancy goldfish and slim-bodied fish, such as most fancy goldfish being slower-swimming and less able to compete for food.

I’m not saying it can’t ever work.

But for MOST situations it is probably best to keep like fish with like.

Some size discrepancy doesn’t seem to be a problem in most cases…

… Unless one fish can fit in the other’s mouth!

There may also be issues when mixing more nippy fish like Ryukins with very visually or physically impaired breeds like Bubble Eyes.

Sure, other fish or tank mates like snails are an interesting addition to the tank and goldfish do seem to interact with them to some degree.

Many tank mates can be useful, such as those that eat algae.

But these just don’t seem to provide the same level of companionship.

At least 2 goldfish seems ideal, with more being better (providing you can maintain the water quality).

How to Introduce a New Fish to Your Goldfish Tank

So now you’re considering getting your goldfish a friend.


If your goldfish has lived alone for a while, there’s a greater chance that they could show some initial signs of being territorial.

Most goldfish really aren’t.

But I’ve had the occasional fish that does show some territorial behavior if they’ve lived alone for a length of time (like they think it’s now THEIR tank).

Good news:

In my experience, this doesn’t last long and can be made even shorter with these simple tricks:

1. Feed your fish.

Feeding your fish in advance gets their mind bent towards food so they won’t be so focused on something new.

Most goldfish will also be very busy foraging which will also provide a good distraction.

You want to curb any nipping behavior as much as possible.

2. Turn the lights off on your tank first.

This will help them not see as well while you complete the next step.

3. While the lights are off, rearrange everything as much as you can.

The theory goes that this helps your fish feel like they are in a “new part of the river” and not on their own turf anymore.

So you help reduce territorial behavior.

It never hurts to do a water change while you do this.

Oh, and this is really important:

Don’t Forget – ALWAYS Quarantine Any New Fish

goldfish in bowl

Image Credit: DJ Srki, Shutterstock

One HUGE mistake I see goldfish keepers make (and sadly one I have made myself) is that in bringing in a new goldfish, they accidentally bring in something else…


In my case, I had a black telescope goldfish all by himself in a 30 gallon tank for several months, and decided it was time to get him a friend.

I found the perfect match and plopped the new fish straight in after matching the temperatures.

They even got along fantastically from the start!

But then something really, REALLY BAD happened.

In about a week, I noticed my old fish was hitting itself on the walls of the tank, despite the water testing fine.

A little while after there were tiny speckles all over its fins and body.

It was a parasite called ich!

Within a few days, he developed full-blown dropsy due to the stress of the parasite attack.

I tried my best to save him, but by the time I figured out what was going on it was too late.

This was all due to a proper lack of quarantine.

I don’t want you to make the same mistake!

I’ve talked to many other fishkeepers who have done the same thing as me. They thought, “if the fish looks healthy, it is healthy.”

But then shortly after they added a new fish, their entire tank is in a state of danger.


… Before you add a new fish, be sure to quarantine it thoroughly.

And quarantine is more than simple isolation.

If you got your fish from a pet store, it involves a minimum of 28 days of treatment to get rid of all these nasty parasites imported fish have 99% of the time.

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So, do goldfish need a friend?

Based on the reasons above, I really believe its a good idea to keep more than one goldfish together in a community tank.

That said:

While companionship is an important part of a goldfish’s life, it shouldn’t come at the expense of their safety.

What do you think?

Are you considering finding your fish a friend?

Let me know in the comments below!

Featured Image Credit: Pixabay