What Are The Best Fishes For 20 Gallon Tank?

A tank of 20 gallons has gained popularity among the fish keepers. It is because it is quite small to set up in the bedroom. But, at the same time, it has enough size to keep a variety of fish. This article will discuss some best fishes with their description, which can be kept in a 20-gallon tank. Also, some relevant factors are included with all the fish to help you choose the best one for you. 

9 Best Fishes For 20 Gallon Tank

1. Guppies

Guppies

Guppies are our first choice for keeping in a 20-gallon tank. Guppies are quite popular due to their stunning colors, ease of care, and peaceful nature. Guppies are very colorful; therefore, they are popularly known as rainbow fish. One can differentiate between male guppies and female guppies by their size. 

Generally, female guppies have a larger size in comparison to male guppies. In addition, male guppies have vibrant colors have a long and thin anal fin, whereas a female has a triangular-shaped anal fin.

Growth Rate

The growth rate of a guppy depends on several factors. Some of them include water parameters, care level, type of food, and many others. For example, a female guppy attains the age of maturity within 1-2 years, whereas a male guppy takes around 3-4 years to be fully grown.

Maximum Height 

Guppies do not have bigger heights. It is the only reason that their fins look extremely amazing while flowing. The maximum height of a guppy is 2 inches. Unfortunately, though, a female guppy can reach up to a height of 2.5 inches, whereas a male guppy hardly attains a height of 2 inches. 

Light Demands

Guppies do not demand any special treatment in the case of lighting. Guppies can survive in sunlight. Therefore, you can keep your fish tank at a place where the sunlight directly comes to the fish tank, such as near a window. Sunlight would be enough for your guppy to stay healthy. 

Difficulty 

It is not difficult to have a guppy in your fish tank. They don’t require much care; therefore, both a beginner and a professional can keep a guppy.

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2. Platy

Platy

Our next choice would be platies. Platies have a very attractive and pleasant look. They are quite calm, small, and energetic. You would get them in different colors and different varieties. One of its species, named Mickey mouse platy, has a unique look and has a mouse ear-shaped tail. 

It is relatively difficult to differentiate between male and female platy. But one can differentiate through their fins. If you find the fins have good width and are flat, it implies the platy is female. If the fins are quite sharp, the platy is male. It would be interesting to keep platies in a 20-gallon tank, but you should keep them in an appropriate ratio. We recommend keeping at least two female platy and one male platy in a tank. 

Growth Rate

The growth rate of platies could vary from species to species. If your platy is not growing, there could be various reasons such as poor water condition, improper care, overcrowded tank, and many other reasons. Generally, platy grows to its maximum size within 5-6 months, if cared for well. But some platies could take around one year to reach their maximum size. 

Maximum Height 

The height of platies varies from male to female. Generally, female platy has a bigger height in comparison to male platy. Their maximum height is 3 inches. The dwarf platy could attain a height of 1-inch maximum. 

Light Demands 

As far as the lighting is concerned, platies do not require artificial lights. It is because they can survive in sunlight, which would keep them healthy. But if you have some live plants in your platyfish tank, there would be some requirements for artificial lights.

Difficulty 

Platy is quite easy to care for; therefore, this fish can be handled by both a beginner and a professional.

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3. Zebra Danios

Zebra-Danios

Danios are freshwater fish and provide a glorious look to your tank. These are available in a variety of colors and types. Zebra danios are quite common because of their peaceful and social behavior. In addition, zebra danios have vertical stripes all over their bodies, making them look unique from other fishes. 

They are generally found in groups. If you keep them with slow-moving fishes, they can become aggressive and start biting the fins of other fishes. They are very active and like to swim freely; therefore, a 20-gallon tank would be the best choice to keep danios. It would be great if you keep your danios with other active fishes. 

Growth Rate

The growth rate of the zebra danios depends on the level of care and water conditions you provide. If you provide a nutritional diet and good water conditions, your zebra danios could grow 1 inch larger within four months. Although some fish take around one year to grow 1 inch longer, this growth rate is generally found in unhealthy fish.

Maximum Height 

The height of danios varies from species to species. Generally, a zebra danio can attain a maximum height of 2 inches. However, if these fish are kept in ponds, they would attain more height. 

Light Demands

Zebra danios would grow faster in artificial lights. They would require a continuous supply of light for at least 12 hours for their healthy growth.

Difficulty 

The care level of zebra danios is very easy. Anyone can keep this fish in their fish tank as they don’t require much care.

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4. Goldfish

Goldfish

As the goldfish’s name suggests, these fish have orange-gold color. Some goldfish can be grey and white with some orange dots on their body. There is a tradition that the groom gifts the goldfish to his wife for their healthy and prosperous life ahead in some places. 

They are omnivores and like to eat plants and small animals. They are social fish and love to swim. Goldfish would be grey and white. Goldfish are not suitable for keeping in a 20-gallon tank with other fishes. 

Growth Rate

The growth rate of baby goldfish is generally very fast in the starting few months; then, you would notice a slight decrease in their growth rate. However, when it comes to adult goldfish, they grow 1 inch every year.

Maximum Height

The height of goldfish depends on the area and the space they live in. If a goldfish lives in a smaller tank, it will not attain much height. Normally, a goldfish does not attain a height of more than 15cm. However, if you keep your goldfish in a large pond, your fish can grow up to 36cm.

Light Demands

The lighting requirements of goldfish vary from type to type. Normally, a goldfish enjoy a mild amount of light. Therefore, it is advised not to add light that provides too much brightness as it could result in eye strain. In addition, you should switch off the lights when you go to sleep at night because goldfish also sleep at night and require complete darkness.

Difficulty 

They are not difficult to care for. Goldfish are relatively sensitive. Therefore, sometimes these fish could require special treatment, especially in any disease.

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5. Neon Tetras

Neon Tetras

Our next choice would be neon tetras for your 20-gallon tank. These fish are quite popular due to their non-aggressive and peaceful behavior. In addition, their body has a unique combination of bright colors that you can’t take your eyes off of. 

You would notice that their color fades in some situations. Mostly it happens when your neon is sleeping or has a serious disease. Sometimes, neon tetras become aggressive for food. But it is quite uncommon.

Growth Rate

Nein tetras are fast-growing fish. They can attain their maximum length within one year. However, there could be some exceptions when the fish takes a long time to grow. This problem is generally faced when neon is suffering from any serious disease.

Maximum Height

When it comes to the height of neon tetras, they can attain an average height of around 1.5 inches. However, if your fish gets good care and lives in favorable water conditions, your neon tetras can attain a maximum height of 2.5 inches. Female neon tetras normally have shorter height in comparison to male neon tetras. 

Light Demands

Neon tetras love to live in a tank with hazy water. Therefore, they prefer a dim light that should match the dark water. Hence, we recommend you use low watt beaming light for your neon tetras tank.

Difficulty 

The level of care is quite easy. It is because neon tetras are non-aggressive, calm, and like to live in a group. So your neon would be happy and more comfortable if you kept it in a group of around 4-5 fish. 

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6. Molly Fish

Molly Fish

Our next choice would be a molly fish. Mollies have an attractive appearance. Their head has a triangular structure, and their body is flat. They have a tail that has a fan shape. Their tail adds a unique look to their appearance. Differentiating between a male and a female molly is not a difficult task. 

You can easily tell by noticing their fins. A male has pointy fins, whereas female fins are wider. Another point of differentiation could be their size. Female molly is larger in comparison to a male molly. They are very calm and peaceful. Therefore, Mollies would do best in your 20-gallon tank. 

Growth Rate

Mollies have an extremely fast rate of growth. A molly would not take more than 3-4 months to reach its maximum length. If mollies get proper care, they can attain their full size within less than three months.  

Maximum Height 

The height of molly could vary from species to species. However, mollies can reach a maximum height of 4-4.5 inches. You would be surprised to know that mollies can even manage their size following the size of the tank. 

Light Demands

Though, mollies do not require any special light. This is because mollies do not show interest in light. But low to medium light would be fine. 

Difficulty 

Mollies are very easy to keep. You would not face any difficulty in looking after your molly. It is because they have a peaceful and friendly nature. You can even keep them calm and non-aggressive. 

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7. Rasboras

Rasboras

The peaceful and social behavior of rasboras makes them one of the best fishes to keep in a 20-gallon tank. Rasboras prefer to live in a group of at least 5-6 fish. Their bodies have bright colors. They glow the tank with their attractive and colorful appearance. Small insects, worms, frozen and live foods are all their favorite diets.

Growth Rate

Similar to mollies, the growth rate of rasboras is also incredibly fast. As a result, these fish can attain their maximum size within three months of birth. 

Maximum Height

As far as the height is concerned, rasboras attain a maximum height of 1.7-2 inches. So you would normally notice that a female has a bigger size than a male rasbora.

Light Demands 

Rasboras don’t demand too bright light. They prefer low to medium light. Bright light can also result in eye strain which would be harmful to your rasboras.

Difficulty 

It is very easy to keep rasboras in the tank. This is because of their non-aggressive and calm behavior. You can even keep these fish in groups.

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8. Swordtails

Swordtails

As their name suggests, these fish have long and pointy tails which provide a sword look. Differentiating a male swordtail and a female swordtail is quite simple. This is because only males have sword-like tails; females don’t. Swordtails have peaceful, social, and non-aggressive behavior. But you would notice that male swordtails become aggressive occasionally. 

Growth Rate

In the initial stage of birth, swordtails have an extremely fast-growing rate. However, later the growth rate slows down. Hence, swordtails attain their maximum length within two years.

Maximum Height

The height of male and female swordtails differs. Normally, a male reaches a height of around 5.5 inches, whereas a female swordtail would be 0.5-1 inch longer than a male. Therefore, their maximum height is around 6-6.5 inches.

Light Demands

Swordtails prefer medium lights to stay active in the day. However, they like the dark environment at night for proper sleep. Hence, it is advised to switch off the lights at night. 

Difficulty

Swordtails are easy to care for. You aren’t required to give any special treatment to your swordtails. They can happily live with other fish in a group too.

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9. Cory Catfish

Cory Catfish

Our last choice would be cory catfish for a 20-gallon tank. These fish have a peaceful and calm nature. Cory catfish are non-aggressive and don’t fight with their tank mates. Whenever some other fish try to attack the cory catfish, they hide at a safe place somewhere between plants. 

Cory catfish spend their whole day sleeping. These fish are also very useful for cleaning the tank. Therefore, cory catfish would be nice to keep in a 20-gallon tank.

Growth Rate

They grow at a medium rate. Normally, it becomes mature within one year. Again, though, the growth rate depends on the diet and water conditions. So a nutritional diet and good water conditions can help your fish to grow faster.

Maximum Height 

The height of cory catfish could vary. However, the maximum height that a cory catfish can attain is around 4 inches. Normally, small catfish do not reach more than 1 inch.

Light Demands

Cory catfish can live happily in standard lights. 

Difficulty 

Since cory catfish are popular due to their peaceful nature hence, it becomes easier to care for your cory catfish. You can also add some other fish to your catfish tank.

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How Many Fish For A 20-Gallon Tank?

This question is very common and is asked by many fish keepers. The number of fish to be added to a tank of 20-gallon depends on the type of fish you have. You would require considering the type of fish, its growth rate, its maximum height, and other relevant factors. As far as small fish are concerned, you can keep around 15-20 fish in a 20-gallon tank. When it comes to fish of bigger size, the number could vary.

Frequently Asked Questions (FAQs)

What Is The Biggest Fish You Can Put In A 20-Gallon Tank?

It is always advised to keep a limited number of fish in a tank according to the size of the tank. The tank should not be overcrowded. Your fish should have enough space to swim freely. The biggest fully grown fish, whose size ranges from 3.5-4 inches, would be ideal for keeping in a 20-gallon tank.

How Many Tetras Can I Put In A 20-Gallon Tank?

The same rule applies to keeping tetras in a 20-gallon tank. You should keep a limited number of tetras in the tank so that it does not reduce the swimming space of your fish. Therefore, we suggest you keep around 11-13 tetras in a 20-gallon tank. 

What Other Animals Can Live In A 20-Gallon Tank?

Some other animals apart from fish can live in a 20-gallon tank. Those include crested geckos, snakes, five-lined skinks, and lizards. However, you should avoid adding crocodiles and turtles in a 20-gallon tank. It is because they attain a bigger size till they fully grow. 

Wrapping Up

Choosing a fish for your 20-gallon tank could be a challenging task. That is why we have discussed all the relevant factors such as growth rate, maximum height, and others for choosing the best fish for your tank. You should consider the above information while you are buying a particular fish. We hope this article will help you buy the best fish for your 20-gallon tank.

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