Small Aquarium Fish: Best Species for Your Tank
Fish tanks and small aquarium fish are often a piece of decoration as well as fish kept in offices, homes, hotels, and many more places. They add life to the space and look extremely beautiful when done correctly.Many budding aquarists and fish enthusiasts begin their hobby by keeping small fishes at home in a small aquarium or a nano tank. To begin with fish keeping, one must know the best fish for a small aquarium.
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Whether you are looking for a fish for a 3.5-gallon tank or a 5 gallon, or even up to 20-gallon capacity, we are here to help you choose the most suitable fish. We will provide you with a list of fishes and information about them for their caretaking, which fishes can be added to your already existing group of fishes, and much more.
Knowing about what you put in your tank is the most essential part, like the fishes, you mix must get along with each other and the environmental parameters in the small fish tank must be suitable for all the breeds of fish you put together.
Another important factor is quarantine, to prevent the introduction of some disease into your small fish aquarium with already existing fishes, you must quarantine the new lot in a separate tank for 4 to 5 weeks.
To begin with, let’s discuss the smallest fish aquarium of a 3.5-gallon fish tank and suitable fishes for the same. The best fish for a 3.5-gallon tank are the ones that generally remain under 2.5cm in length. We will provide you with the information necessary to pick the most suitable fish for your aquarium.
Some of the smallest fishes for the smallest fish aquarium are as follows:
Indonesian Super Dwarf Fish
| Scientific Name | Paedocypris petrogenetic |
| Adult Size | 1.4cm |
| Suggested Tank Size | 2 gallons for a small school of fish |
| Water Temperature | 27 to 32℃ |
| pH Range | 3 to 3.8 |
The Indonesian super dwarf fish is the smallest aquarium fish measuring only about a cm. Its adult size equals the size of an adult mosquito. So it isn’t just a small fish, it’s a nano fish.
This fish is mostly found in black tea swamps of southeast Asia, which are extremely acidic due to the decomposition of tea leaves. Thus, this fish loves to live in water with a pH of 3. Their thin, transparent body along with their small size makes it difficult to look after them.
These fishes are mostly for expert aquarists as they are not easy fish to take care of as they are extremely sensitive to pH levels and thus, difficult to maintain.
Other fishes for a 3.5-gallon tank are:
- A single Dario Dario
- Dracula minnow
- Dwarf rasboras
- Male least killifish
OTHER SMALL FRESHWATER AQUARIUM FISH RECOMMENDED FOR YOUR SMALL TANK OF 5 GALLON, 10 GALLON, OR UP TO 20 GALLONS:
Pygmy Hatchet Fish
| Scientific Name | Carnegiella myersi |
| Adult Size | 2 to 2.5 cm |
| Suggested Tank Size | 10 gallons |
| Water Temperature | 23 to 26.5℃ |
| pH Range | 4.8 to 6.4 |
| Life expectancy | 5 years |
These are gracious and peaceful fishes that easily coexist with others in a small fish tank as long as they aren’t harassed by their tank mates. So they thrive better with equally timid fishes like the corydoras.
It is one of the best community freshwater aquarium fish. At Least 6 of them must be kept together for them to enjoy in the tank. They enjoy calm waters and get stressed by high water currents. They enjoy a meal of insects and bloodworms.
Chili Rasbora
| Scientific Name | Boraras brigittae |
| Adult Size | 2 cm |
| Suggested Tank Size | 5 gallons |
| Water Temperature | 20 to 25℃ |
| pH Range | 5 to 7 |
| Life expectancy | 8 years |
Chili Rasboras, also known as mosquito rasboras are small fishes with peaceful temperament. Beginners can easily take care of these fishes as they are low maintenance. They are carnivorous in nature and their diet includes live or frozen daphnia, brine baby shrimp, and crushed flake.
They are native to Borneo. They are one of the best fish for small aquariums. They are active and cute. Males are bright red with iridescent black stripes running laterally, whereas females are lighter.
Fancy Guppies
| Scientific Name | Poecilia reticulata |
| Adult Size | 5 cm |
| Suggested Tank Size | 5 gallons |
| Water Temperature | 21 to 27℃ |
| pH Range | 7 to 8 |
| Life expectancy | 2 to 3 years |
They are suitable for the smallest fish aquariums due to their tiny size. They breed very often and fill up the tank with their offspring. They are one of the most popular and among the best fish for small aquariums. They can be kept in a group of 5 males or 1 male to 5 females.
Guppies are peaceful in nature and love plants and tropical water. They enjoy an omnivore diet of micro pellets, frozen brine, shrimp, and pellets.
Zebrafish
| Scientific Name | Danio rerio |
| Adult Size | 6cm |
| Suggested Tank Size | 15 gallons |
| Water Temperature | 18 to 25℃ |
| pH Range | 6.5 to 7.5 |
| Life expectancy | 5 years |
Zebrafish also known as zebra danios are fishes, native to south Asia. They have five metallic blue stripes running the lateral course of their body. They must be housed in shoals as they are active fishes who love to play. They have a peaceful temperament.
They are easy to fish to take care of in small fish aquariums. They enjoy an omnivore diet of bloodworms, flake food, pellets, and daphnia.
Endler’s Livebearers
| Scientific Name | Poecilia wingei |
| Adult Size | 2.5 to 4.5 cm |
| Suggested Tank Size | 5 gallons |
| Water Temperature | 26.7℃ |
| pH Range | 7 to 8 |
| Life expectancy | 2 to 3 years |
These fishes are native to Venezuela, closely related to the guppies as they hybridize with them often. Males endlers have intense orange, black and metallic green markings, and they tend to breed a lot.
They must be kept in schools of all males or 1:5 male to female ratio. They are nano aquarium fish of peaceful nature, suitable for beginner fish enthusiasts. They occupy upper levels of water and enjoy eating bloodworms and pellets.
Bluefin Notho
| Scientific Name | Nothobranchius rachovii |
| Adult Size | 6 cm |
| Suggested Tank Size | 5 gallons |
| Water Temperature | 20 to 24℃ |
| pH Range | 6 to 7 |
| Life expectancy | 1 to 2 years |
Also known as the Rachovii killifish, they are suitable for intermediate-level aquarists. These fishes get semi-aggressive if males are housed together. They originate from the Mozambique waters and live in tiny water bodies.
They are nano fishes of vibrant colors with active personalities. They are brightly colored in deep red, metallic blues, and have striped fins. They are predatory in nature and thrive on frozen as well as live foods, baby shrimp, cyclops and bloodworms.
Betta Fish
| Scientific Name | Betta splendens |
| Adult Size | 5.5 cm |
| Suggested Tank Size | 5 gallons |
| Water Temperature | 24 to 27℃ |
| pH Range | 6.5 to 7.5 |
| Life expectancy | 2 to 5 years |
Betta, also known as the siamese fighting fish, is a tropical fish from southeast Asia. they are territorial in nature. They come in numerous varieties of vivid colors and are known to be intelligent in nature.
They are easy to fish to take care of and hence, good for novice aquarists. They need a stimulating environment due to their smart and intelligent nature. Males must be kept alone in a small fish aquarium due to their territorial nature, females can be kept in shoals.
They are carnivores and thrive on insects, bloodworms, and daphnia.
Cardinal Tetra
| Scientific Name | Paracheirodon axelrodi |
| Adult Size | 5 cm |
| Suggested Tank Size | 15 gallons |
| Water Temperature | 22 to 24.4℃ |
| pH Range | 6 to 7 |
| Life expectancy | 4 years |
They are nano fishes that look very much like neon tetra. They thrive in shoals of 6 to 12 fishes and get along well with tank mates like plecos, gouramis, and zebrafish. They have a peaceful temperament.
They are omnivores and eat small pellets, shrimps, live daphnia, and frozen daphnia along with flake food.
Whitecloud Mountain Minnow
| Scientific Name | Tanichthys albonubes |
| Adult Size | 5 cm |
| Suggested Tank Size | 10 gallons |
| Water Temperature | 7 to 21℃ |
| pH Range | 6 to 8 |
| Life expectancy | 3 to 5 years |
Also known by the names Chinese danio, white cloud mountain fish, white cloud, and canton danio. These are easy fish to take care of and thus, well suited for beginners. They need to be kept in the shallows of at least 6 fish. They are most active when the water temperature is cool.
They are known to adapt to a wide range of water parameters. They thrive on an omnivore diet of pellets, daphnia, baby brine shrimp and bloodworms. They are bright golden in color or silvery blue with bright red fins. keep your aquarium brown-algae free
Sparkling Gourami
| Scientific Name | Trichopsis pumila |
| Adult Size | 3.8 cm |
| Suggested Tank Size | 10 gallons |
| Water Temperature | 24 to 28℃ |
| pH Range | 6 to 7 |
| Life expectancy | 4 to 5 years |
Also known as the pygmy gourami, they have deep chest tapering towards the tail and their body is laterally compressed. They are grey or beige in color with bright red or blue speckles. They have large metallic eyes.
They are peaceful, yet hardy in nature. They are suitable for intermediate aquarists. They enjoy a mix of animal protein and algae-based food, including spirulina, micro pellets, and flake food.
Harlequin Rasbora
| Scientific Name | Trigonostigma heteromorpha |
| Adult Size | 5 cm |
| Suggested Tank Size | 10 gallons |
| Water Temperature | 23.3℃ |
| pH Range | 6.5 |
| Life expectancy | 6 years |
They are beautiful freshwater fishes with vibrant ruby-colored, lozenge-shaped bodies, a back wedge marking running from dorsal fin to their tails. They prefer to be in shoals of 6 to 9 fish.
They are easy to fish to care for by beginner aquarists and are of peaceful nature. They enjoy an omnivore diet of bloodworms, frozen daphnia, and high-quality flakes. They are also known as red rasbora due to their ruby-colored body.
Neon Tetra
| Scientific Name | Paracheirodon innesi |
| Adult Size | 2 cm |
| Suggested Tank Size | 10 to 20 gallon |
| Water Temperature | 26.6℃ |
| pH Range | 5 to 5.6 |
| Life expectancy | 2 to 3 years |
They are one of the most popular small freshwater fish and among the best fish for small aquariums, native to the Amazon river basin. They are easy to fish to take care of, which makes them great for beginners.
They have a peaceful temperament and enjoy an omnivore diet of high-quality flakes, baby brine shrimp, and micro pellets. At least 6 neon tetras must be kept together in a small fish aquarium. They are small, thin-bodied fish known for their neon red and blue markings.
Pygmy Corydoras
| Scientific Name | Corydoras pygmaeus |
| Adult Size | 3 cm |
| Suggested Tank Size | 10 gallons |
| Water Temperature | 22 to 26℃ |
| pH Range | 6.4 to 7.4℃ |
| Life expectancy | 3 years |
These are among the best fish for small aquariums and can adjust in the smallest aquarium. They are also known as pygmy catfish. They dwell in the bottom of the tank. Their foreheads are sloped and back, humped.
They are peaceful fishes and one of the best fish in the tank. They enjoy the company of other smaller fishes and thrive on an omnivore diet of sinking pellets, bloodworms, gel foods, etc. they love to be in shoals of 10 or more.
There are many small and nano fishes out there, find the ones suitable for the size of tank you can afford and house them with other fishes that have similar water temperature and pH requirements.
Do not house peaceful fishes with aggressive ones as that will put them in danger, avoid putting aggressive male species together too. Bigger tanks are easier to manage in the long run but if you want a small one, make sure you are ready for the work you need to put in.
There are many creative things you can do to your tank to make it interesting and keep your fish happy.
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