If you’re thinking about starting an aquarium, stocking it with freshwater fish is a good idea. There is a wide variety of fish to choose from, each with its distinct characteristics. All freshwater fish, however, require a certain level of care.
Selecting the right fish for your aquarium can be difficult, so we’ve compiled all the information you’ll need on some of the best fish you can add to your tank.
#1. Guppy Fish (Poecilia Reticulata)
The guppy is a type of freshwater fish in the Poeciliidae family. The guppy’s beautiful, flowing fins and colorful body make it a popular aquarium fish. In addition, guppies are among the most popular tropical aquarium fish.
NOTE: Guppies are shy, peaceful fish that are adaptable, low-cost, and simple to care for, making them an excellent first fish for new aquarists.
Guppies have sexual dimorphism, which refers to the fact that the sexes of the same species exhibit different traits. For example, males have splashes, spots, or stripes that can be any color, while wild-type females are grey. In addition, guppies’ sizes vary widely, but males are typically between 0.6 and 1.4 inches long, while females are between 1.2 and 2.4 inches long.
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Guppies can reach sexual maturity in as little as seven weeks. The average lifespan of guppies in the wild is around two years. Guppies’ life histories differ in different populations, suggesting that various evolutionary forces are at work. In the wild, guppies breed twice a year and they are developed and capable enough to live independently by the time they are born.
Guppies should be kept in water between 78 and 82 degrees Fahrenheit (25.5 and 27.8 degrees Celsius) with salt concentrations of one tablespoon per 5 US gal (19 liters). Guppies can live in marine tropical community tanks and tropical freshwater tanks because they can withstand levels of salinity up to 150 percent that of normal seawater.
DID YOU KNOW: There are over 40 different types of guppies! Check out my article here to learn them all.
#2. Oscar Fish (Astronotus Ocellatus)
Because of their popularity as aquarium fish, among many other names in the aquarium trade, oscar fish is also known as:
- Tiger Oscar
- Oscar Cichlid
- Velvet Cichlid
NOTE: Oscar fish are also among the most mistreated fish in the aquarium hobby. They are typically sold as small juvenile fish in local fish markets.
Generally, they would be sold in 2-inch increments (5 cm). Many people who buy these fish are unaware they can grow to be a foot (30 cm) long in a year. Because of their rapid growth and large adult size, they are frequently kept in aquariums that are too small for them.
This species reaches sexual maturity at around one year and reproduces for another 9-10 years. The occurrence of rain may influence the frequency and timing of spawning. In captivity, Oscar pairs select clean and flat horizontal or vertical surfaces on which to lay their eggs. Smaller females lay 300-500 eggs, while larger females lay 2,500-3,000 eggs.
#3. Neon Tetra (Paracheirodon Innesi)
Neon tetras are a freshwater fish species in the characin family of the order Characiformes. It is native to blackwater and clearwater streams in South America’s Amazon basin. The neon tetra has a silver-white abdomen and a light-blue back.
Like other tetras, their color intensity is affected by their diet and tank conditions. A well-balanced diet of live prey and greenery will help your tetras look their best. An iridescent blue horizontal stripe runs from the fish’s nose to the base of the adipose fin on each side of the fish, and an iridescent red line runs from the middle of the body to the bottom of the caudal fin.
NOTE: Neon tetras are relatively easy to keep and can adapt to a wide range of water conditions. If your tank is stable and adequately cycled, you should have no trouble keeping this species.
The best tank mates for neon tetras are:
- other tetras
- rasboras
- cory catfish
There are noticeable differences between the male and female blue lines. The blue line is curved in the female because she is more rounded. When viewed from above, some aquarists claim that the females appear plumper. A possible explanation for these two features is that eggs cause this look when the female carries.
The neon tetra has an average lifespan of five to ten years in a well-cared-for tank. You can expect this range to decrease if you neglect them for an extended period.
#4. Green Swordtail (Xiphophorus Hellerii)
This freshwater/brackish fish belongs to the Poeciliidae family of the Cyprinodontiformes order. The Swordtail is a livebearer closely related to the southern platyfish or “platy.” It can crossbreed with the south platyfish (X. Maculatus), another livebearer.
From Veracruz, Mexico, to northwestern Honduras, the green swordtail is a native of North and Central America. Passive community aquariums can benefit from swordtails, which are hardy and colorful. Selection breeding allows for the development of new color morphs in swordtails.
Like most livebearers, swordtails are easy to care for and do well in various environments. Swordtails can also reproduce relatively fast if kept in groups. It is recommended they get placed with other fish that are also friendly to the community because they are a small and peaceful species.
About three to five years is a typical life span for swordtail fish. Fish housed in ideal conditions have a higher chance of surviving and reproducing.
NOTE: The “sword” protruding from the tails of male Swordtails gives them their name. Because of their distinctive appearance, they make excellent conversation starters in public aquariums.
#5. Otocinclus/Dwarf Sucker Fish
Catfish of the genus Otocinclus commonly referred to as “Oto,” are small and have a variety of colors and patterns on their bodies. These tiny creatures require a large school and a well-established tank to thrive.
However, these are a great alternative if you don’t have enough room for a pleco. This two-inch freshwater fish can be kept in a 10-gallon aquarium.
Catfish are bottom dwellers. Substrates that won’t cut their fins are essential, as are plenty of rocks and plants to hide in for these creatures. They can be found near the surface of the water but are often found near vegetation or other objects. In contrast to many other loricariids, the male does not build a nest and does not protect the eggs.
NOTE: A healthy Otocinclus can live for five to seven years. The Otocinclus Catfish is a beautiful addition to any aquarium, and if you give it the attention it needs, it will thrive for years.
#6. Bristlenose Pleco (Ancistrus)
The Bristlenose Pleco, also known as the Bushy Nose Pleco or Armored Catfish, is one of the most popular Pecostomus species in the aquarium. Despite its unusual appearance, the Bristlenose Pleco is a peaceful addition to any community aquarium.
Bristlenose Pleco has all of the Loricariidae’s characteristics. That includes a bone-like plate-covered body and a ventral suckermouth. In addition, the fleshy tentacles found on the head of adult males are the most commonly associated with the genus. Females may have tentacles along the snout margin, but they are smaller and lack tentacles on the head.
Bristlenose Plecos can live for 10-15 years if properly cared for and kept healthy. They reproduce quickly in captivity and get along with most other freshwater fish.
NOTE: Though most species are mottled brown or black-and-grey spotted, others are more exotic, with spots of bright yellow on a typical dark background.
#7. Angelfish (Pterophyllum)
Many people are shocked that angelfish can be found in fresh and saltwater. Angelfish have a diamond-shaped body, and long, trailing fins characterize this species. For this reason, they get referred to as the Aquarium’s King. Due to selective breeding programs, regular fin and veil fin varieties are possible in various colors.
In the aquarium, it’s relatively simple to breed angelfish. However, many breeds have lost their instincts for raising young due to generations of inbreeding, so they eat their own young. Long-term relationships between angelfish pairs are based on mutual protection from predators and would-be suitors.
NOTE: Once an angelfishes mating partner has died or been removed from the tank, breeders have found that their remaining partner refuses to mate with any other fish or successfully breed with subsequent partners.
Freshwater angelfish with good genetics can live up to 12 years in captivity with the proper care and living conditions. With no natural predators to contend with, some experts believe they can survive 15 years in the wild.
#8. Betta Fish
One of the most well-known aquarium fish is the betta, also known as a Siamese Fighting Fish. Betta fish were first bred in the Orient more than a century ago to emphasize their color and fins. Due to those efforts, there is a stunning variety of betta fish on the market today.
Bettas are anabantoids, which means they have a unique organ called a labyrinth that allows them to breathe in atmospheric air. Hence, they can survive in low-oxygen environments that would otherwise be lethal to most other fish, such as rice paddies and slow-moving streams.
NOTE: Despite popular belief, you should never try to keep betta fish in a container smaller than 5 gallons. Small bowls are cruel and can significantly shorten a betta’s life span.
Bettas can reproduce in two ways: by building bubble nests or by brooding in their mouths. The latter sometimes get referred to as “pseudo-bettas,” since they evolved from the nest-builders due to their fast-moving stream habitats. Because they don’t have to defend a territory like bubble-nesters, these species lay their eggs in the mouth and exhibit less sexual dimorphism.
A typical betta fish lives for about 2-4 years. The environment where you keep your betta fish directly impacts how long it will live. You can help your fish live longer by keeping their tank clean and paying attention to their diet. Bettas are carnivores.
#9. Zebrafish (Danio Rerio)
When it comes to the hobby of keeping freshwater fish as a beginner, zebra danios are among the most popular. They are highly sought after due to their distinctive striped pattern, lively personality, and low maintenance requirements.
Zebrafish can survive in temperatures as low as 64°F when grouped in groups of five or more. Their favorite place to hide is among underwater plants, where they can blend in perfectly with other danio species.
NOTE: The caudal fin of the zebrafish is adorned with five parallel blue pigmented stripes that resemble those of a zebra. The zebrafish gets its name from these stripes.
In contrast to the male’s torpedo-like shape and gold stripes running between its blue ones, the female has a more extensive, whitish belly and silver instead of gold lines. With its mouth pointing upwards, this creature has a fusiform and compressed lateral shape.
Zebrafish are expected to take three months to produce. Ovulation and spawning cannot take place without the presence of a male.
Zebrafish are asynchronous spawners and can successfully spawn frequently, even daily, under ideal conditions. As long as they are kept in captivity, zebrafish can live for up to five years, but they typically live for two to three years. Their primary food source is tiny organisms found in the slow-moving waterways where they prefer to live.
#10. Dwarf Gourami (Trichogaster Lalius)
Only four countries in the world have dwarf gouramis as their native species:
- India
- West Bengal
- Assam
- Bangladesh
This fish can be found in slow-moving water, such as creeks, streams, and lakes, where vegetation is abundant. Dwarf gourami is popular for newcomers to the hobby of fish keeping, because of their hardiness and eye-catching colors.
NOTE: Dwarf gourami make excellent “centerpieces” for any aquarium because of their vibrant colors and great personalities and are also extremely easy to look after. In contrast to the much larger standard gourami, which can become aggressive, dwarf gouramis are generally peaceful fish.
Most dwarf gouramis live for four to six years; however, they can live much longer with proper care. They do best in a well-planted aquarium with a temperature of at least 75 degrees Fahrenheit.
The male builds a bubble nest that floats on the water’s surface for the eggs. The male bubble nest builders use plants, twig fragments, and other debris to strengthen their nests. Spawning requires a water level of 3–4 inches and a temperature of 86–30 °F (28–86 °C).
#11. Cory Catfish (Corydoras)
Cory catfish are typically found in smaller streams along the banks of larger rivers, marshes, and ponds. They are native to South America’s slow-moving and almost still streams and small rivers, where the water is shallow and murky. Most species are bottom feeders, foraging in sand, gravel, or detritus.
These fish are easy to keep because they are:
- peaceful
- hardy
- active
- entertaining
They occasionally dart to the surface, sticking their snout above the water for a split second to breathe air. That is normal behavior and does not indicate anything wrong with the fish. However, if done in excess, it can mean poor water quality.
Cory catfish are schooling fish, so keep them in groups of at least 4-5. They aren’t picky eaters, so a mix of flakes and pellets should suffice. Dried bloodworms are another excellent supplement that will keep your cories happy and healthy.
NOTE: Cory catfish are frequently held in community nano tanks because they only require a 10-gallon tank. They get along well with small nano fish such as rasboras and tetras.
Under ideal conditions, cory catfish can live for five years or even longer. However, it is common for some cory cats to die soon after being placed in a tank.
#12. Goldfish (Carassius Auratus)
Goldfish are among the most well-known and popular aquarium fish. These highly social species were the first to be bred in captivity on a large scale. Goldfish grow to be quite large, and their beauty is breathtaking.
Contrary to popular belief, goldfish do not grow to the size of their tank. Instead, they need to be kept in an aquarium or pond of the appropriate size for the species chosen. A tank size of at least 20 gallons is recommended for the health and well-being of juvenile goldfish.
NOTE: The recommended amount of water is 5 gallons for every 1 inch of length of an adult goldfish.
Goldfish, like all other cyprinids, lay eggs. Their eggs are adhesive and stick to aquatic vegetation, most commonly Cabomba, elodea, or a spawning mop. Within 48 to 72 hours, the eggs hatch.
Over 1,000 years ago, goldfish was first selectively bred for color in imperial China, and several distinct breeds have since evolved. Goldfish usually live for around 10 to 15 years, with some varieties living up to 30 years if properly looked after. Unfortunately, many Goldfish do not reach their entire lifespan due to poor housing conditions.
#13. Discus Fish (Symphysodon)
The discus fish sides usually have green, red, brown, and blue patterns. Some more vividly colored variants result from aquarists’ selective breeding and do not exist in the wild.
NOTE: Most cichlids are aggressive to their species, but the discus is one of the few cichlids that travel in groups and is content in a shoal of at least five others.
When a pair breeds they move away from the group, possibly to reduce the risk of cannibalism among the young. Brood care is highly developed in this species, as it is in most cichlids, with both parents caring for the young. Furthermore, adult discus secretes mucus through the skin that the larvae feed on for the first four weeks.
Discus lives in home aquariums for an average of 10 years but can live up to 15 years and grow 8 inches long. Like other fish in a home aquarium, they will eat almost anything that fits in their mouth.
#14. Common Hatchetfish (Gasteropelecus sternicla)
The common hatchetfish or river hatchet fish is the largest of the commonly kept hatchets. The common hatchetfish thrives in the warm waters of the central Amazon Basin, from Venezuela to Peru’s lower elevations. This hatchet wears a muted, dashingly attractive coat of bonze-colored scales from the body’s midline down through the bulbous belly.
The river hatchetfish is a schooling species that prefer to be kept in groups of five or more and spends most of its time searching for food at the water’s surface. These fish are friendly to other fish but frequently quarrel among themselves.
NOTE: Hatchets require a tight-fitting lid because of the habit of leaping out of the aquarium when startled.
They are found in tropical streams and prefer water with a pH of 6-7, hardness of up to 15.0 dGH, and an ideal temperature range of 73-81 °F (23-27 °C).
#15. Harlequin Rasbora (Trigonostigma Heteromorpha)
Harlequin rasboras are one of the world’s most popular schooling fish. They put on a beautiful show in aquariums of any size due to their shimmering color and iconic markings.
The harlequin rasbora has an average lifespan of 5 to 8 years. However, most will live until they are about six years old, with reasonable care and genetics determining whether they will live past that age.
NOTE: In terms of breeding, the harlequin rasbora differs significantly from the other popular rasboras in the aquarium.
The female will swim inverted beneath a chosen leaf and rub her belly along the leaf in preparation for spawning. The male adopts a similar inverted position alongside her. As the female extrudes her eggs and attaches them to the underside of the leaf, the male curls his tail fin around the female’s body and emits the sperm that will fertilize the eggs.
Comparison Table
| Fish | Water pH level | Care Difficulty | Diet | Temperature |
|---|---|---|---|---|
| Guppy | 6.8 – 7.8 | Easy | Omnivore | 74 – 82 °F |
| Oscar | 6 – 8 | Moderate | Omnivore | 77 °F |
| Neon Tetra | 4 – 4.8 | Easy | Omnivore | 72 – 76 °F |
| Green Swordtail | 7 – 8.4 | Easy | Omnivore | 72 – 79 °F |
| Otocinclus | 6 – 7.5 | Moderate | Omnivore | 72 – 82 °F |
| Bristlenose Pleco | 6.5 – 7.5 | Easy | Herbivores | 73 – 80 °F |
| Angelfish | 6.8 – 7.8 | Easy | Omnivore | 78 – 84 °F |
| Betta Fish | 6.5 – 8 | Easy | Omnivore | 75 – 80 °F |
| Zebrafish | 6.6 – 8.2 | Easy | Omnivore | 83 °F |
| Dwarf Gourami | 6 – 7.5 | Moderate | Omnivore | 72 – 82 °F |
| Cory Catfish | 7 – 8 | Easy | Omnivore | 74 – 80 °F |
| Goldfish | 7 – 8.4 | Easy | Omnivore | 68 – 74 °F |
| Discus Fish | 6 – 7 | Hard | Omnivore | 82 – 86 °F |
| Hatchetfish | 6 – 6.8 | Moderate | Carnivore | 72 – 81 °F |
| Harlequin | 6 – 7.5 | Easy | Omnivore | 73 – 82 °F |
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