How Big Do Goldfish Get?

Most people remember goldfishes as their first pets – tiny, silent, and extremely fragile. However, did you know that goldfish can grow up to 7-16 inches and can weigh up to 5 pounds in the wild? Guinness World Records recorded the largest goldfish to be 18.7 inches long in the year 2003.

From what you can tell, goldfish can get pretty big – especially in the wild. Being hungry creatures, it is no wonder that they enjoy given enough food and time in the wild, goldfish can become monstrously large. Read on to find out everything you need to know about these beloved pet animals.

How Large Does A Common Goldfish Get?

The size of goldfish mainly depends on its living conditions. Water temperature, cleanliness, and food source greatly affect a goldfish’s growth. The average size of these species, when kept as a pet (commonly in a bowl), is usually 1-2 inches long.

In bigger tanks, they can grow up to 6 inches since a wide swimming space means lots of physical activity. Small bowls and aquariums limit the size of the fish as those who get to swim a lot can grow a lot in size. This is why, in the wild, the common goldfish can grow up to 12-14 inches.

Although the swimming area is a crucial influence, things like the temperature of the water – which is usually warmer in the wild, also matter. The higher the temperature, the more oxygen goldfish consume – and then generally eat more to make up for the energy spent.

Tank Condition For Growth

It is necessary to give your goldfish proper nutrition, but the most important part of fish care is the condition of the tank. Since the water they live in affects them directly, it is important you take care of the vessel your pet lives in. A dirty living environment can stunt the growth of your goldfish faster than hunger can.

The following are a few things to keep in mind when maintaining the condition of a tank to help your fish grow.

Size

It is necessary that you keep your goldfish in a decent-sized aquarium to ensure its healthy growth. Although goldfish can survive in fish bowls, they might not reach their full size if not kept in a container that suits them.

The basic rule of thumb in choosing the perfect size for your fish is to choose a size according to the size of your fish – i.e., 1 gallon for 1 inch. However, there is no fish tank too big for a fish. When it comes to aquariums, bigger is always better.

Water Quality

The quality of the water is also important for the proper growth of your goldfish. Their growth spurt is triggered in warm waters, but keeping still water warm is not ideal for pet goldfish. It is important that you maintain the cleanliness of your tank on a weekly basis, and remove all sorts of dirt that gathers over time.

Contaminated water can also give rise to ammonia and nitrates which are toxic to your fish. The ideal pH level for an aquarium to keep goldfish is between 7.0 and 8.4.

If you do not have a large tank, make sure that the size you have has a good filtration system to not just keep the tank clean, but also keep oxygen levels high in the water as goldfish need it to process their food.

Temperature

You need to make sure that the temperature of the water is ideal for the growth of your goldfish. Warmer water is better for growth, but the temperature that goldfish like is between 68° to 74° F. Water that is hot can cause irritation and disease in our goldfish.

In cold water, the metabolism of your goldfish can go down and energy levels can also decrease – making your pet sluggish. Hence, it is important to maintain the proper temperature of your aquarium water.

Density Of Fish

Even if you buy a 20-gallon aquarium tank for all your goldfish, if you put too many together, it can stunt their growth. Overcrowded tanks are not ideal for fish as they do not get space enough to move or grow properly. You might also find these peaceful fishes fighting over territory.

A good criterion for estimating how many fish to put in a tank is 2 inches of fish per gallon of water. However, since this species can grow really big, another great rule of thumb is to put 1 goldfish for every 10 gallons of water.

Tips to Improve Goldfish’s Growth

The following are a few tips to help you boost the growth of your goldfish and make them enlarge faster.

Feeding high-quality fish food that is rich in protein, like daphnia or brine shrimp can help your goldfish grow faster. It will also help if you add vegetables to your fish diet as goldfish are omnivorous.
A good way to pick out the best food for your goldfish is to make sure that it has at least 60% protein.
If it is possible, try and change the water in your fish tank every day to keep it clean and ammonia-free.
Instead of feeding just once a day, try giving 5-6 small meals throughout the day.
When picking goldfish to put in your tank, try to get the high-quality ones as genetics can also limit the growth of your goldfish.
Do not pick goldfish that are under 2 inches in size as they are more how likely to catch parasites like body and gill flukes.

How Long Does It Take For Goldfish Full Size?

The average growth rate of a goldfish is around one inch per year. The species usually grows extremely fast as young ones and then eventually slows down with time. Goldfish do not stop growing, so you could say that they only reach their full size at the time of their death.

A wild goldfish’s growth spurt is affected by seasons. In summer and spring, when the water is warm, goldfish grow faster and bigger, compared to winters. The following is a table compiled to help you understand how long it will take a goldfish to grow up to a certain size, according to their age.

Size Of Common Goldfish	Age of Goldfish
0.9 inches	1 month
1.5 inches	6 months
2.75 inches	1 year
3.5 inches	1.5 years
4 inches	2 years
4.5 inches	2.5 years
5 inches	3 years
5.5 inches	3.5 years
6 inches	4 years
6.5 inches	4.5 years
7 inches	5 years
7.25 inches	5.5 years
7.5 inches	6 years
7.75 inches	6.5 years
8 inches	7 years

Fancier goldfish, like the Japanese koi carp, can grow to bigger sizes in the same time period. The average life expectancy of a goldfish is 10-15 years, so if your pet lives up to that age, it might be larger than the maximum of 8 inches.

Under good care, they have even survived up to 30 years of age- so size mostly depends on their health.

Do Goldfish Grow To The Size Of The Tank?

It is a popular myth that goldfish grow according to the size of the tank. However, that is not entirely the case, although it is a contributing factor. Most fish, including goldfish, do not have a determined maximum size of how big they can grow – so most of them grow until they die, though extremely slowly.

The size of the tank matters when a goldfish is not kept in a proper tank or bowl. As you may have seen around you or on popular media, goldfish are one of the most mistreated pets. A lot of owners keep goldfish in small, glass containers or do not even take them out of the bag they came in.

Smaller areas also mean faster contamination of water, which can then cause diseases and other health issues, which could have easily been avoided if the size of the tank was proper. In this manner, goldfish grow according to the size of their tank.

Final Thoughts

When taking into consideration goldfish in the wild and at home, it is safe to say that on average, these fishes can grow anywhere from around 6 to 15 inches as long as they have enough room, food, and the right temperature. We hope that this article has been helpful in solving all your queries about how big goldfish can get!