Having a home aquarium is a dream for many fish lovers and new hobbyists. However, there are many constraints, the major ones being space and clarity about which fish to add.

Considering it is just a beginning, you need to ensure the fish you add are easy to care for and can fit into a small community tank.

Let’s begin with the basics first.

Freshwater fish that grow less than two inches are called small or nano fish. They are best suited for small aquariums.

Minimum Tank Size

5 gallons is the smallest fish tank where you can add 1 to 3 small fish of the same type. However,

  • It will require frequent attention to water parameters
  • Provide little space for the fish to move
  • Keeping a single fish type is not advisable. It needs tank mates to socialize with, to be happy.

The next size is 10 gallons. Always better than a 5-gallon fish tank but has the same challenges (insufficient space, lack of variety, frequent attention to tank water quality).

Good tank water quality, and a healthy diet, are essential to keep your tank-dwellers happy and healthy.

Poor tank water quality increases stress levels in the fish, leading to other health complications, which might prove fatal.

Hence, the best small tank size is between 15 to 20 gallons:

  • It will help you add a variety
  • Fish will have enough space to move freely
  • Maintaining the water parameters will be easier
See also  12 Best Freshwater Aquarium Sharks for All Tank Sizes

The table below lists the 21 best small freshwater fish for beginners – care-level – easy.

You can add up to 12 fish under 1.5 inches (or combine a variety up to 2 inches in reduced numbers) to a 20-gallon home aquarium without overcrowding.

Hopefully, this will make it easier for you to finalize your collection.

List of Popular Small Aquarium Fish

The list consists of the important pointers listed below. 

Heading What it includes
Common Names Popular names they are known by
Description Color, Characteristics, Type of fish (Schooling) any other peculiarity, and Diet
Adult Size (Inches) Maximum size the fish can grow
Temperament / Life Span Behavior with tank mates / Average life span
How many to Add / Swim at What-Level in Tank The range includes the minimum number of fish required to be added and maximum you can add in a 20-gallon tank. In case it’s a single number, that’s the minimum number required   Water-level in the tank they normally swim at allows you to mix fish that swim at different levels, so the tank looks full at all levels without overcrowding a particular level
1. Ember Tetra, Dwarf Red Tetra, Fire Tetra, Amanda’s Tetra. Red Tetra
Description One of the smallest aquarium fish with fiery red to orange body
Very active schooling fish
Diet – Omnivore
Read here for more details
Adult Size (Inches) 0.6 to 0.8
Temperament / Average Life Span Peaceful
2 to 5 years
How many to add (Recommended range)/ Swim at What-Level in Tank 6 to 15
Middle level
2. Glowlight Tetra, Glolight, Fire Neon, Glow Neon Tetra, Glolite Tetra
Description Most sought after tropical small fish
Dark silver body with a bright neon red/orange line passing from the center of its body from mouth to the eyes
This neon line glows under a particular angle in dim aquarium light
Active swimmer, Schooling fish
Diet – Omnivore
Read here for more details
Adult Size (Inches) 1.5
Temperament / Average Life Span Non-Aggressive
2 to 5 years
How many to Add / Swim at What-Level in Tank 5 to 10
Lower to Middle level
3. Lemon Tetra
Description Beautiful glassy yellow body with a slight tinge of black in the anal and dorsal fins, and a translucent black tail.
A red ring around their eyes enhances their beauty playful and active shoaling fish
Diet – Omnivore
Read here for more details
Adult Size (Inches) 2.0
Temperament / Average Life Span Peaceful
3 to 8 years
How many to Add / Swim at What-Level in Tank 6
Middle-level

4. Serpae Tetra, Red Minor Tetra, Jewel Tetra or Callistus Tetra, Red Serpae, Serpa Tetra, Blood Characin, Blood Tetra
Description Popular small aquarium schooling fish
Bright reddish-brown, fiery red, or olive-brown bodies with a black mark under the gills
Scales shimmer in tank light like a jewel
Diet – Omnivore
Read here for more details
Adult Size (Inches) 1.6 to 1.75
Temperament / Average Life Span Harmonious
5 to 7 years
How many to Add / Swim at What-Level in Tank 6
Middle-level

5. Black Phantom Tetra, Shadow Phantom Tetra
Description Silver-gray bodied shoaling fish
A unique black mark with a bluish lining behind the gills sets it apart.
Diet – Omnivore
Read here for more details
Adult Size (Inches) 1.4 to 2.0
Temperament / Average Life Span Calm but can nip each other’s fins at times
5 years
How many to Add / Swim at What-Level in Tank 4 to 8
Mid-dweller
6. Exclamation Point Rasbora, Least Rasbora, Sparrow Rasbora
Description

A tiny ray-finned fish for tiny aquariums
Golden yellow bodies with dark green or brown stripes. Slight reddish to orange tinge near the eyes.
A bright black and orange horizontal exclamation running along the center of their bodies on both sides, ending with a black dot mark towards the tail differentiates them from the rest
Diet – Omnivore

Adult Size (Inches) Under 1 inch
Temperament / Average Life Span Peaceful and Shy
4 to 8 years
How many to Add / Swim at What-Level in Tank 8 to 12
Mid-Level
7. Neon Tetra, Neon Fish
Description

A tropical small fish, which is most desirable. Its entire body glows under dark light.
It has a radiant light blue or electric blue body
A distinct shinier blue line in the center runs from the nose to the start of its tail
Its impeccable beauty is further enhanced by a bright red broad line running through the lower belly till the start of its tail
Active, playful schooling fish. Fun to add
Diet – Omnivore

Adult Size (Inches) 1.5
Temperament / Average Life Span Amicable
8 to 10 years
How many to Add / Swim at What-Level in Tank 6 to 24
Mid-dwellers
8. Pygmy Cory Catfish, Pygmy Cory, Pygmy Catfish, Pygmy Corydoras
Description A popular tiny shoaling fish of all times
This black beauty has a shining silvery-black body with a central discreet black line running through its nose to the start of the tail
There is a clear stripe pattern on both the sides of the central line, forming a V-shape overall (like nerves pattern on leaves)
Diet – Omnivore
Adult Size (Inches) 0.7 to 1.0
Temperament / Average Life Span Non-aggressive
Up to 3 years
How many to Add / Swim at What-Level in Tank 4 to 15
Bottom and Middle-Level
9. GlowlightDanio
Description An enticing small schooling petfish with a colorful personality
A wide spectrum of colors with slight differences makes them a natural masterpiece
Most have shiny silver bodies with hues of bright yellow, blue, orange, red, green, turquoise, and black spread across their scaly bodies and transparent fins and tails,
Cover the tank lid, as they are jumpers
Diet – Omnivore
Adult Size (Inches) 1.2 to 1.4
Temperament / Average Life Span Peaceful
1 to 3 years
How many to Add / Swim at What-Level in Tank 8 (20-gallon tank only)
All levels, but prefer Middle-Level
10. Endler’s Livebearers, Endler’s guppy, Cumana guppy, Endler
Description

A live bearing tropical small fish from the Guppy species
An active shoaling fish that gives birth to frys instead of laying eggs (livebearer)
A bright fusion of colors adorns them. Tails are transparent fan-like with a bold colored outline on the sides (full or partial)
Bodies have a combination of colors like silver, green, orange, red, black, and blue, with random patterns making them desirable
Diet – Omnivore

Adult Size (Inches) 1.0 to 1.8
Temperament / Average Life Span Harmonious
2 to 4 years
How many to Add / Swim at What-Level in Tank 3 to 9
Mid to Top-Level
11. Kuhli Loach, Coolie Loach, Slimy Loach, Leopard Loach, Giant Coolie Loach
Description

An unorthodox addition to small aquariums
Natural tank cleaners + create very less bioload of their own
They have worm-shaped bodies with small fins and whiskers on their mouths. Contrast asymmetrical stripes cover their shiny to dull skins in various colors
Diet – Omnivore, Scavengers
Read here for more details

Adult Size (Inches) 3.0 to 4.0
Temperament / Average Life Span Calm and Shy
7 to 10 years
How many to Add / Swim at What-Level in Tank 3 to 6 (20-gallon tank only)
Bottom-dwelling non-swimmers
12. Otocinclus Catfish, Dwarf Suckers, Otos
Description

This small fish is added for algae control and considered to be good tank cleaners
Active shoaling fish
Their mouth acts like suction to suck algae from surfaces. They have very small teeth and two whiskers in their mouths
A horizontal stripe (brown or black) runs across their body from the head to the beginning of the tails. The pattern varies and is slightly smokey
Diet – Omnivore

Adult Size (Inches) 2.0
Temperament / Average Life Span Non-Aggressive
3 to 5 years
How many to Add / Swim at What-Level in Tank 3 to 10
Lower-Level
13. Clown Killifish, Clown Killi, Banded Panchax, Rocket Killifish, Bony Fish, African Killifish
Description

A beautiful small schooling fish for small aquariums
Ensure the tank lid is closed, as they are jumpers
It is rocket-shaped from broad tail to tapering slender body to its mouth and fins in sides
Contrast colored horizontal stripes cover its silver/light brown body. The tail is multi-colored. The body has a fusion of colors like silver, black, blue, golden yellow, red, green, brown, randomly
Diet – Omnivore, Prefer live foods

Adult Size (Inches) 1.2 to 1.4
Temperament / Average Life Span Peaceful and Shy Predators
3 to 5 years
How many to Add / Swim at What-Level in Tank 3 pairs to 16 pairs
Top Level
14. Japanese Rice Fish, Medaka, Japanese killifish
Description

A tiny schooling fish from the Japanese paddy fields has gained ground among hobbyists due to its simple yet elegant appearance

A study suggests that these fish has developed face recognition skills like humans, helping them recognize faces of its species. They fail to recognize inverted faces

There is a blue ring around its eyes, whereas the body is creamish white to creamish yellow in color

Its scales shimmer in the dark, giving it an irresistible glow. There is a slight bluish tinge on its lower body

Diet – Omnivore
Adult Size (Inches) 1.5
Temperament / Average Life Span Non-Aggressive
3 to 4 years
How many to Add / Swim at What-Level in Tank 6 to 12
Mid to Top-Level
15. Honey Gourami, Sunset Gourami, Red Flame Gourami, Red Honey Gourami
Description

A vibrant small freshwater shoaling fish for small aquariums

Their bodies are honey-yellow in color giving them a glow of sunset colors

Narrow body with a small increasing (in height) threadlike sequence of anal and dorsal fins and semi-transparent fan-shaped tail makes it picture perfect for your aquarium

Diet – Omnivore
Adult Size (Inches) 1.5 to 2.0
Temperament / Average Life Span

Amicable
4 to 8 years

How many to Add / Swim at What-Level in Tank

2 to 3
Mid to Top-Level

16. Cherry Barb (Male) Cherry Bard (Female)
Description

A striking small schooling fish for hobbyists and experts alike

Males have shining cherry red bodies with a dark line contouring their lower bodies. Females are light cherry to peach in color, with a darker hue on the upper bodies

A black central horizontal line runs from their mouths to the start of their forked tails

Diet – Omnivore
Adult Size (Inches) 2.0
Temperament / Average Life Span Peaceful
5 to 7 years
How many to Add / Swim at What-Level in Tank

4 (20 gallons tank only)
Top to Mid-Level

17. White Cloud Mountain Minnow, Canton Danio, Chinese Danio, White Cloud, White Cloud Mountain Fish
Description

A freshwater schooling fish apt for small tank

It has a shining brown body with a bluish-green hue on the upper portion.

A black and pinkish fluorescent center line runs from its mouth to the start of the tail and ends with a semicircular black mark

This black semi-circle has an orange tinge around it, covering its transparent tail partially

Its mouth is slightly upwards with a protruding lower jaw

Diet – Omnivore
Adult Size (Inches) 1.5
Temperament / Average Life Span Non-Aggressive
5 to 7 years
How many to Add / Swim at What-Level in Tank

5 to 20
Middle to Top-Level

18. Harlequin Rasbora, Red Rasbora, Harlequin Fish, Harlequin
Description

A popular small  shoaling fish for fish lovers

Shades of copper, pink, orange, silver, red and yellow ooze out on its body randomly. The eyes have a golden circle around them. The forked transparent tail also displays a fusion of colors

A black triangle (almost 90 degrees) commencing a little below its dorsal fin and tapering to the start of the tail, is its distinguishing feature

Diet – Omnivore
Adult Size (Inches) 1.7 to 2.0
Temperament / Average Life Span

Harmonious
5 to 8 years

How many to Add / Swim at What-Level in Tank 5 to 8
Top to Mid-Dwelling
19. Panda Cory, Panda Catfish, Panda Corydoras
Description

One of the cutest small freshwater schooling fish in the hobby-circle

Its body is off-white to pink to creamish.

Instead of scales, it has small bony plates on its body. These thin plates meet at the center of the body from top and bottom, forming a continuous sequential pattern

Three black marks – first on the eye (like a panda), second at the start of the dorsal fin, and third at the start of the tail – are its distinguishing feature

Diet – Omnivore
Adult Size (Inches) 1.5 to 2.0
Temperament / Average Life Span

Peaceful
8 to 10 years

How many to Add / Swim at What-Level in Tank

4 to 6
Top to Mid-Level

20. Green Neon Tetra, False Neon Tetra
Description

A striking small schooling freshwater fish suited for small aquariums

They have a vibrant translucent greenish body with a neon blue central line running from its mouth to the start of the tail

It has a broad red mark from its lower belly to the start of the tail. Fins and tail are transparent

Diet – Omnivore

Adult Size (Inches) 1.0 to 1.4
Temperament / Average Life Span

Calm
2 to 3 years

How many to Add / Swim at What-Level in Tank

6 to 10
Middle and Top-Level

21. Black Neon Tetra, Black Tetra
Description

A gorgeous small schooling fish for a small aquarium

It has a striking contrast caused by its body colors. Its body is semi-transparent green, with a bright black central line running from its mouth to the start of the tail. The fins and tail are transparent

There is a half-red circle around the top of its eye. The balance circle has varying colors like yellow, green, black, or a combination of these

Diet – Omnivore
Adult Size (Inches) 1.5
Temperament / Average Life Span

Non-Aggressive
3 to 5 years

How many to Add / Swim at What-Level in Tank

Mid to Top-Level

Frequently Asked Question

Which fish can I add to a fish bowl?

A tiny aquarium of 5-gallon is suitable for 1 to 3 small fish of the same type. Here, there is a tank setup needed.

As indicated in the minimum tank size section above, it is not an ideal option for various reasons.

Alternatively, some also use a virtual fish bowl with no lid for a single fish. There is no setup needed in this option.

Fish that can live in a bowl with no setup are small or nano fish of a single fish type listed below. As they breed/grow, they will need a bigger tank.

Conclusion

While choosing your fish collection, ensure you:

  • Add fish that occupy different levels of your tank.
  • Avoid adding the maximum number of fish from the range. Always keep some space for them to breed, grow, and move freely. Your fish will thank you.
  • Ensure they make good tank mates and require similar water parameters (temperature, hardness, etc.)
  • Add different personalities that make your tank colorful and lively all the time.
  • Do not add all the fish in one go. Read here for more about Acclimating, Oxygen, and Filtration.

We wish you a happy fish parenting time!

About the Author

Shelby Crosby

Shelby is a passionate fishkeeper who has been writing about fish for over 5 years. She is a pro aquarist and holds a BSc Honors Degree in Wildlife and Fisheries. She creates her own beautiful aquarium layouts and loves to share her knowledge of tropical fish with other hobbyists.

Career Highlights:

  • Has worked with several aquarium manufacturers as a consultant
  • Organized and hosted workshops on freshwater fish keeping at retail stores, educational facilities, and libraries
  • Released content for the amphibian community through her writings

Educational Highlights:

  • BSc Honors in Wildlife and Fisheries in 2011 (University of Northern British Columbia)
  • Completed her undergraduate thesis on the effects of zoochlorella supplementation on the growth and health of fish.

Writing Experience

Miss Crosby is a Freelance blogger; many of her articles are posted online on various blogs. She has also written a few short articles for "Tropical Fish Hobbyist Magazine" in the past. She is a regular contributor to FishParenting.com. Her education, first-hand experience with fishkeeping, and in-depth knowledge in aquaculture make her one of the most competent writers in the industry.

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