How Big Do Goldfish Get? (Let’s Find Out)

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Explaining How Big Do Goldfish Get

I’ve had goldfish as pets for a very long time. I got my first goldfish when I was 8 years old, and ever since, I have had at least one goldfish in my fish tank.

Recently, I moved to my new home in the suburbs and got myself an indoor pond to keep my fish. I added some goldfish to that pond as well.

A few days later, I noticed that these fish were getting bigger than they used to get in my fish tank, and I started asking myself, how big do goldfish get?

I spent some time doing my research and found out that goldfish in ponds grow larger than goldfish that are kept in aquariums. And you will be surprised when I tell you how big these goldfish can get.

So today, I’ll tell you about how big a goldfish can get and how you can achieve the maximum growth of your goldfish. So stay with me till the end as we explore the maximum growth potential of a goldfish.


How Do I Make Goldfishes Grow To Their Full Size?


There are several factors that affect the growth of the goldfish, and these need to be kept in mind so that you can grow your goldfish to its maximum size.

The first thing that you need to do is provide a large space for your goldfish. I personally saw my goldfish grow larger in size when I shifted them to a pond from my aquarium. So if you have your goldfish in a fish bowl, then get them a large fish tank and transfer your fish there.

Image of a 1 feet long goldfish

Make sure you provide appropriate food for your goldfish. If the fish is not fed properly, it will become malnourished and will never be able to grow to its maximum size.

Along with good food, make sure the living conditions are also correct. Make sure that you regularly change their water and use a filter in your tank.

Also, keep a close eye on your fish to identify any irregular behavior. This is usually a sign of declining health, which can stop your goldfish from growing to its full size or, even worse, take its life.

Also, make sure that the environment is peaceful and that there are no aggressive tankmates to cause any stress to your goldfish.


How Big Do Goldfish Get?


Well, the answer to this question depends upon several factors. These can be the size of their aquarium or the diet that they get. Their genetics also play an important role in how big they can get.

Similarly, a fish that is properly fed can also grow larger in size compared to one that is not properly fed. The living condition of the goldfish also determines how big a goldfish can get.

If all the necessary conditions are fulfilled, and the fish has a good living conditions as well as a good diet, gets proper light, and a relaxed environment to live in, then an average goldfish that spends all of its life in a medium-sized fish tank can grow up to 6 to 8 inches in length and can weigh anywhere around 0.2 to 0.6 pounds.

However, this is only because of the confined space. Goldfish in larger tanks or in ponds can grow even bigger. A goldfish that spends its life in the wild, living in rivers or ponds, can often reach a size of 12 to 15 inches and can weigh around 5 to 6 pounds.

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How Big Do Goldfish Get In A Tank?


A goldfish can grow to different sizes in different tanks. The size that a goldfish can achieve in a tank mainly depends on the size of the tank. If there are much fish in a single 40-gallon tank, then the goldfish will not grow a lot in size.

The maximum size a goldfish can reach in a fish tank also depends on the diet it is being given. If the fish is being given a low protein diet, then the fish will remain healthy, but it won’t be able to achieve the maximum size even if it has a larger tank to itself.

Image of goldfish with a black background

The condition of the tank itself and the water in the tank will also play a vital role in determining how big your goldfish will get.

If all conditions are perfect, then a goldfish that has a 100-gallon tank to itself can grow up to 12 inches in size and can probably weigh around 3 to 4 pounds.


How Big Goldfish Get In The Wild?


A goldfish can grow much bigger in size in the wild compared to if it is kept in a fish tank. Although space is no more an issue when it comes to wild habitat, there are still many factors that can affect the growth of a goldfish in the wild.

In the wild, goldfish may get more space, more light, and more food as well, but similarly, they may also become more prone to different bacteria and parasites. The chances of a goldfish catching a disease are much higher in the wild as compared to in a fish tank.

Image of big goldfish pet released in wild
Credits: MURDOCH UNIVERSITY

Also, there are many predators in the wild from which the goldfish will have to protect themselves. This will cause them stress.

But if a goldfish in the wild is able to protect itself from all these issues, then it can grow up to 14 to 16 inches in length and can weigh around 5 to 6 pounds. Although bigger goldfish have been spotted, this is the average size they can grow to.


What Is The World Record For The Biggest Goldfish?


There are many reports of goldfish that have grown up to 14 or 15 inches in length, but the world record for the biggest goldfish is held by a goldfish that was able to grow up to a length of 18.7 inches.

The Biggest Goldfish
Biggest Goldfish

It is not absolutely necessary that each and every goldfish reach this size. But this shows the growth potential these fish have. And this is why owners are encouraged to get larger tanks for their goldfish.


There Are Several Factors That Affect The Size And Growth Of Goldfish


The very first thing that determines the maximum size of your goldfish is their genetics and life history. But even if your fish belongs to a family that can grow to be big, the place in which the goldfish is kept will also determine its maximum size.

A fish kept in a fish bowl will never be able to get bigger than a fish that lives in a large pond. This is because, in a larger space, goldfish have more free space to move around, which increases their activity and keeps them in better health, which allows them to grow to their full potential.

Image of goldfish in a lake

Apart from a large space, appropriate nutrition also plays a vital role in determining how large a goldfish can grow. If the fish is not fed properly and all the important nutrients are not provided, this will affect the fish’s health, which in turn affects the growth of the fish.

Another important factor that affects the growth of your goldfish is the condition of the place where it is kept. If the tank or pond in which the goldfish lives is not cleaned, there is a chance that there will be bacterial growth in the habitat, which will make the fish sick and restrict its growth potential.

The quality of the water is also very important. Even if the tank or pond is clean, the water has a higher ammonia content, which will cause ammonia poisoning, which will result in stunted growth of the fish.

One factor that mostly goes unaccounted for is the temperature of the environment. Goldfish thrive at a temperature of around 50 to 60 degrees. Any temperature above or lower than this will also affect the overall growth of the goldfish.

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Final Verdict:

So in order to conclude this blog, I would say that these goldfish may seem like small fish, but they do have a lot of growth potential. If they are provided with the correct conditions, ample space, clean water, and a proper diet, they can grow really big.

I would suggest everyone that owns a goldfish get bigger tanks and go the extra mile while taking care of their fish so they can see these beautiful fish grow to their full potential.


Frequently Asked Questions

#1 – How Long Does It Take For Goldfish To Grow Full Size?

This depends on the specie of goldfish. Slim-bodied goldfish can take up to a year to grow to their full size due to their slow growth, but fancy goldfish can grow to their full size in about 6 months.

#2 – How Big Will Goldfish Get In A 20 Gallon Tank?

If you wish to see your goldfish grow to its maximum size, then only keep one fish in a 20-gallon tank. This will give the fish enough space, and they will be able to grow up to 10 inches.

#3 – How Big Is A 1-Year-Old Goldfish?

The goldfish’s age has very little to do with its size. A one-year goldfish in a fish tank might be the same size as a one-year-old goldfish in the wild.

#4 – How Big Do Goldfish Get In A 40 Gallon Tank?

A 40-gallon tank will be able to house up to 4 or 5 goldfish. But if you want your goldfish to reach a length of around 10 to 12 inches, only keep a maximum of 2 fish in a40 gallon tank.

#5 – How Big Do Goldfish Get In A 5 Gallon Tank?

A 5-gallon tank is only suitable for young and small goldfish. A goldfish that is kept in a 5-gallon tank may only be able to grow to around 2 to 3 inches in size.