Rainbow fish are some of the most popular and beautiful freshwater aquarium fish. They get their name from their striking iridescent colors and horizontal stripe patterns. There are many different species and varieties of rainbow fish that originate from parts of Indonesia, Australia, and Papua New Guinea.
Characteristics of Rainbow Fish
All rainbow fish share some common characteristics:
- Bright, metallic-looking colors like blue, green, red, orange, gold, and purple
- Horizontal stripe patterns on their bodies
- Size ranges from 1-6 inches long depending on species
- Peaceful community fish suitable for community aquariums
- Omnivorous; eat insects, crustaceans, plant matter
- Schooling fish that should be kept in groups of 6 or more
- Prefer well-planted tanks with plenty of swimming space
- Soft, slightly acidic water conditions
- Tropical fish that need warm water around 72-82°F
While they share some traits, the different rainbow fish species and varieties can be identified by their unique color patterns, body shapes, and fin shapes. Here are some of the most popular types of rainbow fish commonly found in the aquarium trade.
Threadfin Rainbowfish
Threadfin rainbowfish (Iriatherina werneri) originate from freshwater streams in parts of Indonesia and New Guinea. Some key features of threadfins include:
- Slender, torpedo-shaped body profile
- Prominent dorsal fin that extends from mid-body to tail
- Males more colorful with red or orange fins
- Metallic blue-green bodies with a red horizontal stripe
- Peaceful schooling fish ideal for community tanks
- Max size around 3.5 inches
Neon Dwarf Rainbowfish
As their name suggests, the neon dwarf rainbowfish (Melanotaenia praecox) is one of the smallest rainbowfish species. Some features include:
- Petite fish that only reach 1.5 inches long
- Slender body shape
- Bright neon blue horizontal stripes on silver-gray bodies
- Anal and caudal fins have yellow-orange coloration
- Hardy fish perfect for nano aquariums
- Peaceful schooling species
Boeseman’s Rainbowfish
Boeseman’s rainbowfish (Melanotaenia boesemani) is a popular large rainbowfish growing up to 4-5 inches long. It has these characteristics:
- Elongated torpedo-shaped profile
- Shimmering silver body with electric blue and red horizontal stripes
- Bright yellow-orange fins
- Larger size requires at least a 30 gallon aquarium
- Peaceful but active swimmers that need open space
Lake Tebera Rainbowfish
The Lake Tebera rainbowfish (Melanotaenia herbertaxelrodi) comes from freshwater streams in New Guinea. It has these notable features:
- Laterally compressed body shape
- Males display brilliant red fins and belly
- Metallic sky-blue bodies with horizontal red stripes
- Grows to around 4 inches long
- Does best in planted aquariums with gentle water flow
Dwarf Neon Rainbowfish
Dwarf neon rainbowfish (Melanotaenia praecox neona) is an exceptionally small rainbowfish that maxes out under 1 inch long. Some key traits include:
- Tiny size under 1 inch makes it one of the smallest rainbowfish
- Shallow compressed body shape
- Bright neon blue bands on a silver body
- Peaceful nano fish for tiny aquariums
- Male fins may show hints of yellow or orange
Irian Red Rainbowfish
The Irian red rainbowfish (Glossolepis incisus) is named for the males’ vivid red coloring. Here are some notable features:
- torpedo-shaped profile with large eyes
- Males display bright crimson-red bodies and fins
- Females are more muted with yellow or silver coloring
- Grows to around 3 inches in length
- Peaceful community fish best kept in schools
Pasama Rainbowfish
Pasama rainbowfish (Glossolepis pasama) come from rivers in New Guinea. Some characteristics include:
- Elongated body shape with rounded fins
- Horizontal brown bands on a silver-gray body
- Males develop yellow-orange fins as they mature
- Grows to around 5 inches long
- Schooling fish that prefers heavily planted tanks
Banded Rainbowfish
The banded rainbowfish (Melanotaenia trifasciata) is aptly named for the dark vertical bands along its body. It exhibits these features:
- Compressed body disk shape
- Silvery background with 3-4 dark vertical bands
- Reddish median fins and bright blue margins on other fins
- Grows to 5-6 inches in length
- Does well in medium to large sized community aquariums
Turquoise Rainbowfish
The turquoise rainbowfish (Melanotaenia lacustris) derives its name from its vivid blue horizontal stripes. It displays these qualities:
- Torpedo-shaped profile
- Silvery base color with electric neon blue stripes
- once maturity yellow median fins
- Reaches around 4 inches long
- Schooling species that appreciates planted tanks
Checkered Rainbowfish
As the name indicates, the checkered rainbowfish (Melanotaenia splendida) has a checkered pattern on its body. Other features include:
- Streamlined fusiform body shape
- Greenish background with checkerboard mosaic pattern
- Tapered tail fin with red coloration
- Attains a length of 3-4 inches
- Shoaling fish best kept in groups of 6 or more
Millaa Millaa Rainbowfish
The Millaa Millaa rainbowfish (Melanotaenia duboulayi) is named after the Millaa Millaa Falls in Australia where it originates. Some key traits are:
- Elongated narrow body
- Horizontal blue-green bands on a silver-gray body
- Reddish-orange fins
- Grows to around 4 inches long
- Peaceful schooling fish for planted community aquariums
Forktail Rainbowfish
The forktail rainbowfish (Pseudomugil furcatus) gets its name from the forked shape of the male’s tail fin. It exhibits these characteristics:
- Slender torpedo body shape
- Horizontal red stripes on a pale silver background
- Males develop lyre-shaped forked tails and orange dorsal fins
- Grows to about 2.5 inches long
- Peaceful nano fish suitable for small tanks
Keyhole Rainbowfish
Keyhole rainbowfish (Melanotaenia australis) have a distinctive “keyhole” black marking on their bodies. They exhibit these features:
- Slender elongated body profile
- Silvery base color
- Black “keyhole” mark on mid-body
- Reddish fins
- Reaches approximately 4 inches long
- Shoaling species that should be kept in schools
Praecox Rainbowfish
The praecox rainbowfish (Melanotaenia praecox) is a small brightly colored species. Some notable characteristics include:
- Torpedo-shaped body with rounded fins
- Horizontal neon blue-green bands on silver
- Orange to red coloration on unpaired fins
- One of the smallest species growing to 2 inches
- Suitable nano fish for small community tanks
New Guinea Rainbowfish
The New Guinea rainbowfish (Melanotaenia affinis) comes from freshwater streams in New Guinea. It displays these qualities:
- Slender elongated body shape
- Horizontal red bands on a pale silver-gray background
- Reddish median fins and yellow-orange on other fins
- Attains a length of around 5 inches
- Peaceful schooling fish for community aquariums
Lake Kurumoi Rainbowfish
Lake Kurumoi rainbowfish (Melanotaenia parva) are native to Lake Kurumoi in New Guinea. They exhibit these features:
- Small elongated torpedo-shaped body
- Turquoise blue horizontal stripes on a silver body
- Yellow-orange unpaired fins
- One of the smallest species reaching 2 inches long
- Suitable for nano aquariums
- Peaceful community fish
Duboulayi’s Rainbowfish
Duboulayi’s rainbowfish (Melanotaenia duboulayi) originates from Australia. Some distinguishing characteristics include:
- Slender tapered body shape
- Silvery base color with 3-4 horizontal brown stripes
- Reddish median fins and yellow-orange pelvic fins
- Attains a length around 4 inches
- Shoaling species ideal for community tanks
Spotted Rainbowfish
As the name suggests, the spotted rainbowfish (Melanotaenia maccullochi) has distinctive spots. It exhibits these features:
- Elongated narrow body profile
- Silvery background color with black spots over the body
- Yellow median fins and blue on other fins
- Grows to around 5 inches long
- Shoaling fish that needs to be kept in groups
Western Rainbowfish
The western rainbowfish (Melanotaenia australis) comes from rivers in western Australia. Some key traits are:
- Slender laterally compressed body
- 5-6 bold black vertical bars on a silver-gray body
- Vivid red median fins and blue margins on other fins
- Attains a length of 4-5 inches
- Active shoaling fish best kept in groups of 6+
Conclusion
In summary, there are a diverse range of rainbow fish that come in many different colors, patterns, and fin shapes. While they vary in appearance, most display characteristic horizontal striping on an iridescent body and share a peaceful temperament perfect for community aquariums. Some of the most popular types covered here include threadfins, Boeseman’s, turquoise, millaa millaa, praecox, and the dwarf neon rainbowfish. When choosing rainbow fish, you can select species based on size, appearance, and behavior that best suits your tank setup.
| Rainbowfish Species | Origin Location | Colors | Size | Unique Traits |
|---|---|---|---|---|
| Threadfin Rainbowfish | Indonesia, New Guinea | Blue-green body with red stripe | 3.5 inches | Prominent dorsal fin |
| Neon Dwarf Rainbowfish | Australia | Neon blue stripes on silver | 1.5 inches | One of the smallest species |
| Boeseman’s Rainbowfish | New Guinea | Blue, red stripes on silver | 4-5 inches | Larger rainbowfish |
| Lake Tebera Rainbowfish | New Guinea | Blue body with red stripes | 4 inches | Males have bright red fins |
| Dwarf Neon Rainbowfish | Australia | Neon blue bands on silver | Under 1 inch | One of the smallest |