How Many Goldfish In A 20-Gallon Tank? Owners Ask, We Answer

Have you ever wondered how many goldfishes could be in a 20-gallon tank?

Do you know what fishes need to have in a 20-gallon tank?

You are in the right place!

Here you will find out how many goldfish can live in a 20-gallon tank. Also, you will learn more about them and what they need.


How Many Goldfish In A 20 Gallon Tank?

1.What Size Tank Should You Get?

If you own goldfish, you’ve probably found yourself in a dilemma because you don’t know how much space one fish needs. Tanks can be found in all shapes but also in all dimensions. Of course, the bigger ones have a higher price. You can buy a tank of 2.5 up to 250 gallons of water. It is usually advisable to take a larger tank because the fish are growing. Fish are sensitive and can get stressed if they are in too small a space. Also, if your fish grow, or if you want to have more fish, you will need a larger tank. Therefore, it is better to get rid of unnecessary costs and buy a bigger tank right away.

2.What Size Tank Is Best For The Goldfish?

During the purchase of a goldfish tank, its size is estimated, how much it will grow and how much space it takes up decorations and other things it needs. People usually take a 20-gallon big tank for one goldfish. This size is perfect for a single fish because it then has enough space to move, swim and explore. So if you want two goldfish you need a 40-gallon big tank. They will then have enough space and will be healthy. Depending on how many fish you have, increase this number by twenty per goldfish. This ratio applies to smaller fish. They could live in a smaller tank, for example in 10 gallons of water, but to be happier and healthier they need more space. Note that smaller tanks will require more and more frequent cleaning. The fish will get the water dirty quickly and will need to be replaced. When you change the water often, it also means that you have to move the fish to the water at different temperatures when cleaning, and that is very unhealthy for them. Therefore, it is a better option to take a larger tank, which you do not have to clean so often.

3.Tank Size &  Goldfish Species

As mentioned, goldfish can be of different species, so they can grow differently. If you own a fancy goldfish, which you can spot everywhere, they are a frequent guest in aquariums, but you can also notice that they can grow larger than other fish of this species. Therefore, you will need to prepare a larger cage. Slim goldfish can be in smaller tanks because they don’t need a lot of space. After all, they do not grow much. There are also goldfish with hoods. They will need more space because they need more air, and a larger tank allows them to breathe oxygen more easily. Before you buy a goldfish, check what species it is and what its characteristics are. That way you will know how much I can grow and what you can expect. Do not keep fish in too small a space as this will only make them sick faster. Orandas are one of the species of goldfish that will also need more space. They also have a hood that requires more surface area for water.

4.Age Of Your Goldfish

When buying a goldfish check how old it is at the time of purchase. This will help you in the future when you buy a tank. It is advisable to buy a tank after you buy a fish to know how much space it needs. If you buy a young fish that is a few months old, then you need to buy a tank the size of it when it is fully grown. To know this, consult the seller or explore the internet. If you buy an old fish, it will not be full-grown and you will automatically know how much space it needs. So, if you are wondering how many goldfish can you have in a 20-gallon tank, the answer is simple, you need to explore the type of fish and its age. For a small fish, which you find will no longer grow, less than 20 gallons is enough. But for a young fish that is just beginning to develop, 20 gallons will be just right, and you may need to consider buying a larger tank as well. Their lifespan is between 10-15 years, but many fish of this species fail to live to old age due to unfavorable conditions. Therefore, you must carefully choose the size of the aquarium, so that they do not get sick. You also need to provide good conditions in the aquarium. Good conditions must be present outside the aquarium as well. If you have other pets, such as noisy parrots, you need to keep the fish as far away from it as possible because it could eat it.


5.The Depth of the Aquarium Is Important

Just as the size of the aquarium is important, so is its depth. Fish like to swim the entire length of the aquarium, but they also like to go deep. But some species like to stick to surfaces. As mentioned, these are mostly the ones that have a hood. They will mostly stay on top of the aquarium and will not like to swim deep. These fish love the surface because the air is close to them, but also then they are closest to the food that is inserted into them and stays on top of the aquarium. Examine the shapes of the aquarium as well. There are very large circle-shaped ones, you can put a lot of fish, grass, and decorations in them. But there are also rectangular-shaped ones, they fit a lot of decoration, and fish love it because they have a lot of space to swim in all directions. Make sure the aquarium is in a good place and that your fish are always clean.

6.Check the Surface Area

As already mentioned, some fish require more air and therefore more surface area. There are deep tanks that do not have a great length, but there are also those that are shallower but with enough surface area. Fish that have a hood often need a surface area to be able to breathe oxygen more easily. Every fish is different, but each of them loves shallower aquariums. They do not like great depths and will prefer to stay close to the surface. Goldfish will enjoy it if they have a long aquarium. They will then socialize more and play with other fish, will be happier, will breathe easier, and will feed better. Statistics say that for one inch of fish, you need to have twelve inches of surface free space. There are several ways you can recognize low oxygen in aquariums, so follow those signs.

7.What If You Don’t Have Space for a Large Tank

Fish love large aquariums, but sometimes you just don’t have enough space in the house for one big aquarium. Also, sometimes such aquariums are simply too expensive. The best way to avoid this problem is to buy fewer fish. Make sure the fish does not grow into a large one, that it is healthy, and that it will be happy in a smaller aquarium. Think about where your aquarium will stand, and if you don’t have room in one part of the house, try imagining an aquarium in another part. If you still can’t find places, try to find an aquarium of some shape. For example, some aquariums are made in the shape of letters, shapes, or your wishes. If you want a smaller aquarium make an effort to search all the shops, and the internet to find the perfect aquarium for your goldfish.

8.Types Of Tanks 

There are many types of tanks. You can find cheap ones at the markets, but some are not of good quality. Before buying a tank you need to check its strength, beauty, and size. Be careful because there are a lot of gallons. For example, you can buy a tank that is up to 250 gallons in size. Also, you have to be careful because tanks come in different shapes. You can buy the shape of a circle, rectangle, letters as desired, but also for different purposes. When buying a tank, you must also pay attention to how big you want it and where you would place it in your house. Aquariums are large, expensive and you don’t want them to be in a place where they are easy to damage, or where you can scare the fish. Do not keep the aquarium in noisy rooms, or near the kitchen.

To Sum Up

Here you could learn how many goldfish to place in a 20-gallon tank. There are many interesting species of this fish. But each is different. To buy a large enough aquarium, you need to know everything about your fish. You need to know if your fish will continue to grow if they need a lot of oxygen, and you need to know how much other equipment will take up space. If you need a tank, check this post about the best 20-gallon rimless aquariums or the best 20-gallon breeder tanks.

Joana has graduated in Linguistics in 2014. and began her work experience as a journalist and freelance writer. Her professional writing experience, as well as experience with pets, brought her to Petovly where she’s an editor. Working on the site, she collaborates with vets and animal shelter workers she has met when she was volunteering as a student. This experience made her an expert in pets’ care, breeds, and diseases.