Top 10 Best Exotic Freshwater Fish for 20 Gallon tank

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Written By Fun Fish Tanks

I Love my Fishes 

A freshwater tank does not mean that you can’t have exotic fish species. There are exotic freshwater species that you can keep in your aquarium.

Everyone wants exotic species as they have magnificent colors and make your aquarium stand out. Saltwater species are not the only species that are magnificent, freshwater species also don’t lack such colorful fishes. 

In this article, we have listed the best exotic freshwater fishes for a 20-gallon tank. All these fishes are beautiful and live up to their name as exotic species. 

1. Cherry Barbs 

Source: Fish Laboratory

Cherry barbs are sociable, schooling fish that are quite active. When in groups of six or more, the species flourishes.

Freshwater fish belonging to the Cyprinidae family include the cherry barb. The fish has a characteristic lateral stripe running the length of its body, is tiny, and has a brilliant red color.

When in groups of six or more, the species flourishes. The fish is well-liked by both novice and experienced aquarists. 

Keep the water between 74℉ and 79℉, with a pH of 6 to 7, and with a hardness of 2 to 18 dGH.

Dim illumination is ideal. The cherry barb’s vivid red color is highlighted by the dark, sandy substrate, which also makes the fish more comfortable. Establish hiding places for the fish, such as caverns, vegetation, rocks, and driftwood.  

2. Koi Betta 

Source: Light Fish

The Koi Betta Fish is exceptionally beautiful. It has a koi fish-like color pattern. They got their name from the color patterns and color parts that resembled koi.

When compared to the marbled betta, they are fairly pricey and typically have patches of black, yellow, red, or orange hue.

Koi betta should thus be kept in warm water that is at least 22–26°C. Additionally, the water should be of excellent quality and the temperature should be steady.

Soft water with a pH of 6.0 to 8.0 should be neutral to mildly acidic. To simulate their native habitat, the water flow should also be maintained to a minimum.

One betta male should be kept with at least five sororities of females. Never house two male koi bettas together. Koi betta fish typically eat insects and bug larvae in the wild.

Live insects and larvae should be fed to them while they are kept in captivity. They will, however, quickly become used to consuming frozen and freeze-dried items.

If you decide to feed them pellets and flakes, add live or frozen items to the diet as a supplement.

3. Apistogramma 


The Apistogramma or Dwarf Cichlids are magnificent species of fish. They are adorned with bright vibrant colors.

The temperament of Apistogramma is semi-aggressive. They are quite lively and will approach the tank walls as you peer inside.

An excellent option for a communal tank is Dwarf Cichlids. They will coexist successfully with other fishes and love dwelling on the bottom of the tank

The Apistogramma prefer water temperatures ranging between 72℉ to 86℉. The pH levels must be around 6.0 to 7.0.

The water hardness is between 2 to 15 DKH. Dwarf Cichlids are omnivorous. Algae is frequently selected as the main course when it comes to plant-based cuisine. When they are hungry, they may also nip at the leaves of plants.

They will consume plants, but they often choose the protein. You can give them brine shrimps and worms. Pellets are also a great choice for nutrition. Continue using sinking pellets that are nutrient-rich.

4. Samurai Gourami 

Source: Aquadiction

A cautious species of freshwater fish belonging to the Osphronemidae family, the samurai gourami is rarely seen in aquariums at home. One of the various varieties of gourami fish, samurai gouramis requires particular attention.

These fish favor low illumination, hot temperatures, acidic water, and lots of hiding places in the aquarium. Due to the high degree of maintenance this special species of gourami requires, it is not recommended for novice aquarium keepers.

It can live alone, in communities of six to eight members of the same species, or with other bottom-dwelling fish. 

70 to 80°F water is the ideal temperature for samurai gourami to live. When the males are brooding, the temperature should be greater. The males risk dying if the temperature falls too low when they are brooding. The pH must range from 4.0 to 5.0.

Samurai gourami favors a tank configuration that resembles quiet rivers and has minimal water movement. When changing the tank’s water, be careful. Samurai gouramis inhabit regions with stable water conditions.

5. Marbled Hatchetfish 

The most popular Hatchetfish in the aquarium hobby is the marbled hatchet fish. The Marbled Hatchetfish is considerably smaller and will not exceed 1.75 inches in length.

The water temperature preferred by the Marbled Hatchetfish ranges between 74℉ to 80℉. The pH levels must be around 5.6 to 6.5 and the water hardness of 2 to 12 DKH. 

As with the other hatchet fish, you can use floating plants, but these fish may also thrive on taller plants that resemble grass and have leaves that reach the water column.

Keep in mind that Marbled Hatchetfish uses the hanging roots from floating plants as hiding places.

However, since they swim more actively, Marbled Hatchetfish require adequate water area. Conduct frequent water testing and replace the water by 50% every two weeks. 

Because they are carnivores, Marbled Hatchetfish require a consistent diet of animal proteins. Various bloodworms, fruit flies, tubifex, and protein flakes should be given.

6. Kribensis

Source: Aquadiction

The Kribensis Cichlid is a stunning, tranquil, and extremely easy-to-keep fish. They are among the species that are most tolerant to spectators due to their distinctive color pattern and comparatively high activity level.

Male Kribensis Cichlids typically measure approximately 4 inches in length, while females typically measure 3 inches. When kept in captivity, the lifespan of a Kribensis Cichlid is often no longer than 5 years. 

These species of fish find harmony in water temperatures between 75°F to 79°F. The pH levels must be between 5.0 to 8.0 and water hardness must be 5 to 20 DKH.

You should use fine gravel for the substrate. These fish frequently dig about in the tank’s bottom and tend to adhere to it. The breeding season is a time when this is especially true. One of the most crucial elements in a tank containing Kribensis Cichlids is a cave.

7. German Ram 

Source: Aquarium Co-Op

Freshwater fish belonging to the Cichlidae family includes the German blue ram. The fish is little, bright, and covered with lovely blue patterns. German blue rams are calm and flourish in communal tanks, unlike the majority of cichlids.

However, because they are sensitive to changes in water, these fish are relatively challenging to care for. 

German Ram does well in water temperatures around 80℉ to 86℉. The pH levels must be around 5.0 to 7.0 and the water hardness must be between 6 to 14 DKH.

Create a variety of hiding places around the tank with caves, driftwood, and plants, and keep the lighting low to mimic the German blue ram’s natural environment. 

It is also beneficial to have plants and hiding places. So keep some caves, driftwood, and other decors in the tank. The substrate must be fine sand.

8. Pea Puffer 

Source: Fish Lab

Pea Puffers are cute species of fish and they come from the Western Ghats of South West India. The pea puffer has a highly distinctive appearance, which is where its name came from. Their bodies appear to be fairly hefty and substantial.

The front begins at the mouth with a little tip and thickens up toward the center of their bodies. The caudal fin of pea puffers is also interesting-looking.

When you’re watching these fish, they might be difficult to recognize because it’s fairly transparent and little in size. 

When fully mature, pea puffers are around 1.5 inches in length. Pea puffer lifespans range from four to five years. The Pea Puffer fish prefers a water temperature of around 72°F to 82°F.

The pH levels must be around 7 to 8 and water hardness should be 5 to 15 DKH.

9. American Flagfish 

Source: Aquarium Fish India

The American Flagfish is not one of the standard aquarium options. The Flagfish is a little fish. You may anticipate it to reach a length of 2 inches in an aquarium.

A tank for an American Flagfish must be at least 10 gallons in size. Since they would often be stored in pairs, start with at least 20 gallons.

Simply because this species is accustomed to lakes and ponds with plenty of open swimming areas, an aquarium with an excessive number of plants is not a smart choice either. 

The American Flagfish prefers swimming around the bottom and middle areas of the tank. The preferred temperature range for them is 66℉ to 85℉ and the pH levels for them are between 6.5 to 8.0.

10. Sparkling Gourami 

Due to its rarity in home aquariums, the glittering gourami is a particular and distinctive fish. They are a fantastic option for anyone wishing to add a dash of creativity to their tank because of their lovely scales, colors, and compatibility.

Despite not being schooling fish, Sparkling Gouramis nevertheless prefer to be in groups of five or six. Although mostly docile, they occasionally display aggression toward other males. When it comes to claiming their area, they are very competitive. 

They prefer a temperature range between 71℉ to 80℉. Water should have a pH between 6 and 8 and a hardness between 5 and 18. Sparkling gouramis may survive in an environment with low oxygen levels and require a sluggish water flow.

Use a low-powered filter since they dislike fast water flow. Regarding the lighting, take into account their passion for plants. The fish and all of the vegetation in your tank will require the lamp. It just has to be left on for around 9 to 10 hours.


Having a freshwater tank does not mean you can’t keep exotic species. There are enough of them to keep in your tank and these species are sure to make your tank look amazing. All the different fish species listed here are the best exotic species for 20 gallons. Get one for yourself if you wish to own exotic species.

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