The Coolest Freshwater Fish for a 20 Gallon Tank

There are quite a few options out there when you’re looking for freshwater fish for a 20 gallon tank. If you are searching for unique options that are going to give you visual appeal as well as something special to care for, you’re in the right place.

Below are a list of 7 fantastic options to give you original flair and a whole lot of fun.

Take a look and see which of these you’d like to add to your 20 gallon tank. Or, you could add in all of them!

The Best Freshwater Fish for a 20 Gallon Tank

Since a 20 gallon tank is often the most popular option for those who enjoy aquariums, you’ll find all sorts of stocking options.

If you’re looking for a leading hand on where to start — especially if you’re a beginner — here are some user-friendly fish to consider.

All sized to fit in your tank, these options will give you a great sense of unique attitudes and great visual appeal.

1. Apistogramma

These are a great option to start with because they’re social creatures! They enjoy moving around from the middle of the tank to the bottom and hanging out with different fish.

Very colourful and easily some of the most distinctive to look at with their flame tipping, they’re well-loved with good reason. They do tend to prefer warmer water, so keep that in mind if you have other fish who prefer a cooler climate.

While they are beautiful, you’ll want to make sure that you keep the water warm and as clean as possible to keep them in good health.

2. German Blue Ram

Easily one of the most distinctive fish you can consider in your tank, these beautiful patterned fish — with hints of blue — are gorgeous.

For the best results as far as atmosphere and visual appeal, combine one male with two females. While beautiful and sure to catch your eye as they swim past, you do have to keep their needs in mind.

The German Blue Ram does like things to be hotter for comfort, so you’ll want to pair these with other hot water fish.

3. Harlequin Rasbora

To give you a little something extra, you can add about eight of these to your 20 gallon tank. These little guys enjoy staying in schools, so it could be stressful to have only one to two in your tank.

Particularly small at only 2”, these are very durable fish and can hold up against some of the cooler and harder water.

These are some of the best schooling fish for those who are beginners with aquariums.

If possible, try to add these to tanks with other calm fish, as they themselves tend to be pretty calm and quiet.

Video credit Joeri Van Dessel.

4. Julidochromis

One of the coolest details about this fish is that they have the unique ability to swim vertically as well as sideways and even upside down.

Fascinating to watch and a great option for those that do just enjoy sitting back to watch their fish, these are great. As far as capacity, you can add about 3-6 of these to your tank. You’ll want to make sure that you provide enough rocky “furniture” to your tank, though, so that they all have hiding places.

These little 3” fish are pretty peaceful and can often enjoy living with other fish who like to hang out at the top of the rank or in the middle.

5. Leopard Danio

This unique 20 gallon fish looks very similar to a trout, but he’s adorably tiny.

With the option of either short or long fins, these fish are pretty to look at.

You can have around 6 of these in your tank, but make sure that you pair them with fast-paced mid-tank fish. These little guys are very fast moving, especially when they have friends to play with. They also will have no problem eating up any and all food that they can find.

Another feature about this speckled fish is that they are very social. Have kids that like to have fish who interact with them?

These are the ones to do it!

Lastly, these are especially durable fish. From varying temperatures to hard water, they’ll respond fine.

6. Panda Corydoras

These guys are pretty cute with these black and white markings that show where they earn their names from. They often are about 2” and you can have more than six in a tank without an issue. Preferring cooler temperatures, these guys are very calm and serene.

They enjoy hanging out at the bottom of your fish tank and generally sticking to themselves (or with their friends).

Fun to watch because they’re so soothing, they’re also great beginner fish.

7. Pseudomugil Gertrudae

Distinctive and very beautiful in their blue eyes and fluctuating body colour, these fish are small, popular, and very much full of personality.

They can be added to your rank in groups of six and you’ll find it entertaining to have a mix of genders.

Known for their dance to bring the ladies, the male fish will dance around and can be especially fun to watch.

This fish are especially great to consider when you have muted colours in your tank as well as your other fish. These are very colourful and are great to photograph.

The Bottom Line

Sometimes it can be hard to figure out what fish to add to your aquarium. Whether you are an experienced fish owner or you are a beginner just looking for 20 gallon aquarium stocking ideas, all of these will offer you something different. Whether you want a social fish or a pretty fish — or both — this list has it all.

Always make sure that you check the temperature of water that your fish prefer. You’ll want to be careful when combining Panda Corydoras with German Blue Ram, for instance, as one prefers cold whereas the other prefers hot water.

Populate your aquarium carefully, and enjoy all 20 gallons however you see it best to do so!

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