The 10 Most Colorful Freshwater Fish to Liven Up Any Aquarium - AZ Animals

Often, fish are people's very first pets. To some, they are just stepping stones to "bigger and better" companions like hamsters, dogs, or cats. Other times, fish are the only pets some people ever want! This might be because pet fish are quieter and considered to be less work to take care of than other house pets. No matter what your situation is, having a colorful, eye-catching aquarium adds tropical flair to the room and provides an exotic, engaging conversation starter for guests. Having said that, here are 10 of the most colorful freshwater fish you can add to your old, boring aquarium to liven it up!

1. Guppies (Poecilia reticulata)

Fancy-tail guppies are one of the most common guppies in the world. They are also known as fan-tailed guppies or fantail guppies.

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Guppies, which are native to South America, are easily one of the most popular colorful freshwater fish you can keep in your aquarium. This species is the most widely distributed tropical fish species and a fantastic choice for those looking for minimal-effort pets. They are the perfect beginner fish for starting out an at-home aquarium, and for good reason, too! Guppies, otherwise referred to as millionfish or rainbow fish, are exceptionally easy to care for. Their one main preference is for a well-planted tank with clean, oxygen-rich water. Sand, dirt, or tiny rocks are best for guppies since they can get trapped underneath rocks or plastic tank "gems". Coming in a wide variety of beautiful colors, guppies are among the best freshwater fish to liven up your aquarium!

Guppies can be solid colors like blue, red, black, and yellow. Alternatively, other guppies display multiple color combinations with a mix of red, blue, green, yellow, orange, black, and white scales. Some even possess a vertical snakeskin pattern or, more rarely, transparent skin!

Most Colorful Guppies

Dragon mosaic guppies are colorful freshwater fish to fill your aquarium with, coming in shades of red, orange, blue, violet, and yellow. Another beautiful guppy is the blue-variegated delta, which features bright orange-red fins with blue patches, gradient blue side scales, and orange blotches. Some say one of the prettiest guppies is the blue Moscow, which is known for its eye-catching metallic sheen and bright blue color. Others favor the yellow top swordtail, a rare guppy with a sword-like extension at the top of their tail. It is also identifiable for its psychedelic yellow coloration or its muted mix of pastels. Besides their beautiful exterior colors, guppies breed readily, making it even easier to grow your fish colony at home!

2. Beta Fish or Siamese Fighting Fish (Betta splendens)

Bettas were domesticated 400 years ago when the King of Thailand started breeding them to fight for sport. Since they belong to the gourami family, they are naturally aggressive and very territorial.

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First discovered in Southeast Asia, betta fish are native to Thailand, but can also be found in the neighboring countries of Malaysia, Indonesia, Vietnam, Laos, and Cambodia. Bettas are a type of fish that belong to the anabantid family, which includes 137 other unique species. These fish are also known as labyrinth fish because of their lung-like labyrinth organ, which allows them to breathe air. This gives them the ability to live in areas where other fish could not survive — like the cup-sized containers many pet stores store them in (please, do NOT keep them in those tiny cups).

To continue, bettas naturally thrive in shallow, freshwater areas like rice paddies, marshes, ponds, slow-moving streams, and floodplains. Because of this, their tanks require soft plants, low-current filters, and large tanks with a variety of hidey holes. It is also suggested to keep lids on their aquariums, as this species is prone to jumping.

Bettas are known for their vibrant colors and flared, flowing fins, making them the perfect colorful freshwater fish to liven up your aquarium! To start, they come in just about every shade imaginable. The most common colors include blue, black, red, green, yellow, pink, white, purple, orange, and turquoise. The rarest color of betta fish is true purple, with these fish selling for hundreds to thousands of dollars in some cases! This costly fish is not even the most colorful though, so you are in luck if you are looking to liven up your aquarium — without breaking the bank, of course.

Rainbow betta fish are a wonderful option due to their striking array of scales. Alternatively, dumbo ear betta fish are great colorful freshwater fish to make your aquarium stand out. This variety is often a bright cobalt blue color with distinct, large pectoral fins that resemble elephant ears — or Dumbo's ears, if you are familiar with that Disney classic from the early 1980s.  

3. Neon Tetra (Paracheirodon innesi)

Unique to only certain fish species, neon petras have the unique ability to change their coloration in response to the lighting of the environment.

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The neon tetra fish species is one of the most common tropical freshwater fish in the aquarium trade industry. They are native to South America and can be found throughout Brazil, Columbia, Peru, and Venezuela. This species thrives in the Amazon River Basin and the headwaters of the Tiger, Napo, and Yarapa rivers. Additionally, they can survive in various clear or blackwater streams and tributaries throughout the tropical parts of the continent. In terms of their habitat, they prefer waters with slow-moving currents. Since they are tropical fish, they also cannot handle cold water temperatures or high levels of nitrates. To identify them, neon tetras generally have bands of bright green, red, or blue scales across their bodies.

Furthermore, neon tetras are non-aggressive fish, making them the perfect choice for your diverse at-home aquarium. They are also shoaling fish, which refers to any group of fish that stay together in the same area to socialize. For this fish species, this means that they do best in groups of six or more. They pair well with a wide variety of fish, including other tetra species, dwarf gouramis, guppies, swordtails, and harlequin rasboras. Having said that, you should never keep just one neon tetra. Additionally, you should never pair them with goldfish or any large, aggressive fish species.

4. Cardinal Tetra (Paracheirodon axelrodi)

Cardinal tetras are frequently mistaken for neon tetras due to their similar appearances, but they are their own unique species entirely!

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Tetra is the common name of many small freshwater characiform fishes. Another example of this kind of colorful freshwater fish, apart from neon tetras, is the cardinal tetra. Like its renowned cousin, this species also originated in South America — specifically, the Amazon Basin area. They can also be found naturally throughout the Orinoco and Negro rivers in Venezuela and Brazil, respectively. Because of their native tropical habitat, they need warm aquarium water in the range of 72 to 81 degrees Fahrenheit to remain healthy and happy. Additionally, they require a diverse diet to ensure they are getting all the correct vitamins and minerals they require. Since they practice omnivorous lifestyles in the wild, you can feed them a mix of live or frozen food, flake food, and pellets.

To identify a cardinal tetra from a neon tetra, you must first look to see which one is bigger; cardinals are often larger in size, especially if they are female. On top of that, cardinal tetras have a distinct blue or red scale striping that makes them easily identifiable. This marking runs the whole length of their body, whereas in neon tetras, the stripe starts in the middle of their body.

5. Flame Tetra (Hyphessobrycon flammeus)

If kept with too few other fish, flame tetras can become timid or ill-tempered. If this happens, add more fish for them to socialize with. Increasing plant coverage in the tank can also make them more comfortable.

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Yet another fish in the tetra family is the flame tetra. These fish get their fiery name due to their vibrant red and glowing yellow-orange scales. Similar to the previous tetras, this freshwater fish species is native to the Orinoco River Basin area. In the wild, they thrive in slow-flowing coastal rivers, creeks, tributaries, and backwaters. Translating that to aquarium ecosystems, flame tetras prefer a well-planted tank with subdued lighting and dark gravel. River sand, driftwood, and twisted roots are all beneficial tank inclusions as well. While considered easy to take care of, these fish require tank water temperatures between 72 and 82 degrees Fahrenheit with a water pH of 5.5 to 7.5.

6. German Blue Ram (Mikrogeophagus ramirezi)

Part of the ram cichlid fish family, German Blue Rams are named for their unique, bright blue coloration.

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German Blue Rams are another ideal freshwater fish to liven up your aquarium! They have a striking electric blue exterior with vibrant yellow accents — often around the head and neck area. Plus, their gold or silver underbellies provide a sharp contrast, making this fish easy to spot in aquariums. German blue rams are considered relatively peaceful, but sometimes get aggressive if they are kept in too small of an aquarium or if they are protecting their eggs. They are from South America and prefer a well-established tank with plenty of hiding spots. Their water temperature must also stay between 78 and 86 degrees Fahrenheit, with an average pH level of between six and seven.

7. Boseman's Rainbowfish (Melanotaenia boesemani)

As rainbow fish age, their intense color becomes even more vibrant, especially during times of high stress or when males are seeking mates.

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As the name suggests, Boeseman's Rainbowfish have stunning rainbow-colored bodies, with shades of blue, orange, and yellow being the most predominant colors. They originated from Indonesia, where they thrived in the warm waters of the Ajamaru Lakes and their tributaries in West Papua. In the wild, they prefer shallow bodies of water with lots of vegetation to seek shelter in. The lakes in this area all have hard, alkaline water with a pH of eight to nine. When kept as pets, their aquariums should match their natural habitat as closely as possible. Additionally, they require a lot of open swimming space.

Though beautiful, this fish species might not be the best choice for your amateur home aquarium. This is because they are so hard to find, and realistically, should not even be kept as pets. To explain further, Boeseman's rainbowfish have been threatened by over-harvesting since they became a popular aquarium fish decades ago. This resulted in their name being put on the red list of endangered species in 2004, where they have remained to this day.

8. Harlequin Rasbora (Trigonostigma heteromorpha)

Harlequin rasboras are natural schooling fish and should be kept in groups of at least 8 to 10, though larger schools make for an even more impressive aquarium display.

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Native to Malaysia, Thailand, and Singapore, harlequin rasboras live in freshwater bodies of water. Their preferred habitats range from peat swamps and forest pools to streams with lots of vegetative coverage and plant matter. This freshwater fish species is widely known for its striking combination of black, orange, and silver scales. They are fairly passive in personality and get along with just about any other fish species as long as they are not large or predatory. If you plan on adding this fish to your aquarium, make sure to include lots of driftwood and plants to hide in. Moreover, they prefer dimly lit environments with a water pH between 6 and 7. While the harlequin rasbora can handle living in waters with a maximum pH of 7.8, it needs to be much lower for breeding.

9. Dwarf Gourami (Trichogaster lalius)

Similar to betta fish, dwarf gourami are labyrinth fish. This means they need to have access to the water's surface so they can breathe the air.

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Native to India, West Bengal, Assam, and Bangladesh, dwarf gourami inhabit densely vegetated waters. It prefers slow-moving waters in rivers, streams, and lakes with a pH range of 6 to 8. To mimic their natural habitats, their tank's water should be kept between 72 and 82 degrees Fahrenheit.

This freshwater fish species is notable thanks to its brightly colored scales that feature vibrant shades of blue, red, and orange. Males tend to have orange and light blue vertical stripes along their sides and tail fins, whereas females are much duller with shimmering silver-gray scales. Since dwarf gourami are larger fish than some of the others on this list, they prefer to occupy the upper part of the water column. For reference, in a 10-gallon tank, only three dwarf gourami should be housed.

10. Threadfin Rainbowfish (Iriatherina werneri)

Threadfin rainbowfish perform best when kept in small groups of less than six, preferably with two female fish to every male.

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Another rainbowfish that can help liven up your aquarium is the threadfin rainbowfish. This brightly colored freshwater fish has scales that range from gray-green to yellow, red, or blue — with the color extending through its fins. Threadfin are widely considered the most beautiful of all the rainbowfish subspecies due to their long, flowing fins. Along with their bold coloration, their fins are also great attention-catchers as they zoom through their aquarium!

For background, these fish are native to Australia but can also be found in parts of New Guinea. They live predominately in freshwater swamps and other densely vegetated bodies of flowing water. Threadfin rainbowfish can grow to be up to two inches in length, but this does not include their long tails. Having said that, their long tails also help to identify the sex of each individual fish. For reference, males typically have larger, flashier finnage than females.

If you add these freshwater fish to your tank, make sure to optimize the habitat for them by including aquatic plants. Additionally, they need clean, slow-moving, and well-oxygenated water with lots of open space for swimming. By doing this, you can ensure they will be happy and healthy in your aquarium!

Conclusion

Remember, fish are living creatures that rely on you to maintain their health and well-being. Though many people consider fish to be the easiest pets to care for, it is not as easy as throwing them in a bowl and feeding them once a day! Instead, you must research the specific care requirements of each fish species you have, as well as their compatibility with other fish (if you plan on mixing species). Other important information to be aware of prior to diving into getting a pet fish is knowing what tank size is suitable for the species you desire, as well as their preferred water parameters and required diets. Taking the time to provide both the appropriate care and habitats for all of your fish is crucial to guaranteeing a healthy and happy aquatic environment for your fish!

Summary of the 15 Most Colorful Freshwater Fish

Number	Fish Species	Scientific Name
1.	Guppies	Poecilia reticulata
2.	Betta Fish (also known as Siamese Fighting Fish)	Betta splendens
3.	Neon Tetra	Paracheirodon innesi
4.	Cardinal Tetra	Paracheirodon axelrodi
5.	Flame Tetra	Hyphessobrycon flammeus
6.	German Blue Ram	Mikrogeophagus ramirezi
7.	Boeseman's Rainbowfish	Melanotaenia boesemani
8.	Harlequin Rasbora	Trigonostigma heteromorpha
9.	Dwarf Gourami	Trichogaster lalius
10.	Threadfin Rainbowfish	Iriatherina werneri

Overview of the most colorful freshwater fish you can add to your aquarium to liven up the tank.

The photo featured at the top of this post is © satit_srihin/iStock via Getty Images