The delightful Longfin Blue Danio is a stippled silvery blue and has long, flowing fins!

The Longfin Blue Danio is a wonderful color variation of the well-known Zebra Danio, but it is earning popularity in its own right due to its subtle but gorgeous silvery blue stippling and long, delicately flowing fins. Another common name it is known by is the Longfin Blue Zebra Danio. This graceful fish was probably developed from the Leopard Danio variety of the Zebrafish as it sports the spotted patterning for which popular mutation is known.

This small beauty will reach only about 1 1/2 inches (4 cm) in length but should not be confused with another similar danio species, the Blue Danio or Kerr’s Danio Danio kerri. Though they both have blue coloring, they are quite distinctive from each other. The Danio kerri is slightly larger at just under 2 inches (5 cm) and lacks the long fins. It also has a powdery blue color on its flanks contrasted with one or more strong, pinkish-gold horizontal stripes running from the tail to about halfway up the body. The stripes can be broken, but overall this fish lacks the spotted effect of the Longfin Blue Zebra Danio.

This charming little Cyprinid is an ideal choice for beginners but is also enjoyed by advanced aquarists. Like its progenitors, it is very lively, hardy, and a prolific breeder. It is pretty typical of the danio group, friendly enough but definitely active and fast-moving. This schooling fish should be kept in a small group of at least 5 individuals, though 10 or more makes them happier and creates a lively display. Although it may bicker and chase others of their same species, without company, these fish will be miserable and ultimately die.

A school of these small, lively fish are well suited to a smaller, 10-gallon aquarium, but a 20-gallon tank is optimal. They can be housed with most any community fish as long as care is taken to make sure that the danio will not be eaten and that the other fish aren’t startled by swift movement. Like all the Zebra Danio varieties, they can withstand an impressive range of water temperatures and conditions and will generally do just fine without a water heater. They can be comfortable in temperatures down to the low 60s (F). However, though they are not finicky about water conditions, it’s best to not keep your aquarium at any extreme.

To create a very attractive effect in your aquarium, try a mixed school by combining the pretty Longfin Blue Zebra Danio with some regular Zebrafish. A mix like this will provide a nice contrast of swiftly moving, darting color. Mixing even more varieties like the Albino Zebra Danio, Golden Zebra Danio, and Leopard Danio works equally well and creates a really exciting display. Don’t be surprised if the school spends a lot of time in the water flow of the filters or pumps as this is reminiscent of the swift-moving waters found in their natural environment.

Scientific Classification


Longfin Blue Danio – Quick Aquarium Care

Aquarist Experience Level:Beginner
Aquarium Hardiness:Very hardy
Minimum Tank Size:10 gal (38 L)
Size of fish – inches1.6 inches (3.99 cm)
Temperature:64.0 to 75.0° F (17.8 to 23.9&deg C)


Habitat: Distribution / Background

The Zebra Danio Danio rerio (previously Brachydanio rerio) was described by Hamilton in 1822. They are found in Asia from Pakistan to India and as far as Myanmar.

The Longfin Blue Danio is a man-made cultivar, but its ancestry can be traced to the Zebra Danio, and it was most likely developed from the Leopard Danio mutation. Many are produced for the aquarium industry. Another common name it is known by is the Longfin Blue Zebra Danio. There are no wild populations of these color morphs.

In nature, Zebrafish prefer the lower reaches of streams, canals, ditches, and ponds. However, their habitat varies depending on the time of year. During the wet season, they are found in large numbers in seasonal pools and rice paddies where they feed and spawn. Then the adults migrate back to faster moving waters, and the young follow when they reach maturity. The substrate of the clear freshwater streams is normally rocky and shaded, while the still waters are silty with dense vegetation. In the wild, these fish are considered micropredators and feed on worms, small aquatic crustaceans, insects, and insect larvae.

  • Scientific Name: Danio rerio
  • Social Grouping: Groups
  • IUCN Red List: LC – Least Concern – There are no wild populations of this color morph.


The Longfin Blue Danio has a slender, compressed body and a barbel at the end of each lip. These small fish reach lengths of only up to about 1 1/2 inches (4 cm) in the aquarium. Their progenitors, Zebrafish, are thought to be primarily an annual species in the wild, but captive-bred varieties can have a lifespan of 3 to 4 years, and some have lived up to 5 1/2 years with proper care.

This color morph of the Zebra Danio has a stippled, silvery blue pattern. There are no other varieties of this fish, which was probably developed from the Leopard Danio as it has the spotted patterning of that Zebrafish mutation.

This fish should not be confused with the Blue Danio or Kerr’s Danio Danio kerri, which is an entirely different species. The Blue Danio has powdery blue flanks with one or more strong, pinkish-gold horizontal stripes running from the tail to the fins. The Blue Danios stripes can be broken, but they lack the stippling of the Longfin Blue Zebra Danio. Finally, the Blue Danio is also a bit larger, reaching almost 2 inches (5 cm), and without the long fins.

  • Size of fish – inches: 1.6 inches (3.99 cm)
  • Lifespan: 4 years – They have an average lifespan of about 3 1/2 years, though some have lived up to 5 1/2 years with proper care.

Fish Keeping Difficulty

Longfin Blue Danios are a great choice for a beginning aquarist, and they make great companions in a community aquarium. They adapt very well to different tank setups and can handle minor tank condition fluctuations without issue. They are usually very easy to feed and get along with most tankmates. These are long-finned fish, so keep an eye on their long, delicate fins.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

Since they are omnivorous, these fish will eat most any prepared or live aquarium fare, though the food does need to float at the surface. A balanced diet for them would include flake or pelleted foods, plant-based food, and occasional live prey. As with all danios, these fish are quite active and have high nutrient requirements, so select a flake food that will provide for their needs. These fish will do best when offered food several times a day, but offer what they can eat in 3 minutes or less at each feeding. If you feed only once per day, provide what they can eat in about 5 minutes.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day – Offer only what they can consume in 3 minutes or less with multiple feedings per day.

Aquarium Care

These fish are not exceptionally difficult to care for provided that their water is kept clean. At least 25 to 50% of the tank water should be replaced once a month. If the tank is densely stocked, 20 to 25% should be replaced weekly or every other week. Aquariums are closed systems, and regardless of size, all need some maintenance. Over time, decomposing organic matter, nitrates, and phosphate build up and water hardness increases due to evaporation. Be mindful during maintenance that these fish will jump, so keep a close eye on them.

  • Water Changes: Monthly – If the tank is densely stocked, water changes should be done every other week.

Aquarium Setup

The Longfin Blue Danio is fairly hardy and will adapt to most aquarium conditions. This schooling species will spend most time in the top and middle regions of the tank, particularly if there is open water or water current. Though a school of danios can be kept in a smaller aquarium, they will do best in about a 20-gallon size. Provide good filtration and keep the tank covered to prevent jumps.

These fish are most effectively displayed in tanks with subdued lighting and a fine, dark gravel or sand substrate. They like a well-planted aquarium, and a variety of plants will make them feel safe. Dense tall plantings around the sides and back are great, but these fish prefer open water in the middle of the tank for swimming.

  • Minimum Tank Size: 10 gal (38 L) – Though a school of danios can be kept in a smaller aquarium, they will do best in about a 20 gallon size.
  • Suitable for Nano Tank: Yes
  • Substrate Type: Any
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 64.0 to 75.0° F (17.8 to 23.9&deg C)
  • Range ph: 6.0-8.0
  • Hardness Range: 2 – 20 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: All – They will spend most of the time in the top and middle regions of the aquarium, particularly if there is open water or some current.

Social Behaviors

The lively Longfin Blue Danio makes a good community fish. It will get along with its own kind and most other species, but these danios really need to be kept in a group to feel comfortable. They are best kept in a school of 5 or more of their own kind. Groups of this fish can be hierarchical, so a pecking order may emerge in the school, but nothing will come of it.

Select tankmates with a similar in temperament that can keep up with the fast-paced lifestyle of this fish. Danios have been known at times to harass other fish, and tankmates that need a calmer environment can become stressed. Don’t keep them with fish that can eat them or fish that demand a peaceful aquarium. Also, their long flowing fins are a temptation too great for any fin nipper to resist, so pick tankmates carefully.

  • Temperament: Peaceful – They are good community fish with other fish that are also fast-moving.
  • Compatible with:
    • Same species – conspecifics: Yes – They are best kept in groups of 5 or more.
    • Peaceful fish (): Safe – These are very lively fish, so pick tankmates that will not be bothered by their activity.
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Monitor – Schools of these very active fish may make calmer tankmates nervous.
    • Shrimps, Crabs, Snails: Safe – not aggressive
    • Plants: Safe

Sexual differences

Males are slightly thinner and smaller.

Breeding / Reproduction

Breeding the Longfin Blue Danio is very easy, and may even occur on accident. Two fish will form a breeding pair, which they often keep for life. If you wish to retain the young, the breeding tank should be empty except for a 2-inch layer of large glass marbles, 1/2 to 1 inch in diameter. Add the female to the tank and let her settle for about a day before adding the male. When they are both in the tank, adding a few cups of cold water will cause the courtship to begin.

If conditions are favorable, the female will release her eggs in open water, and the male will fertilize them. The eggs will then sink to the bottom and fall through the marbles, out of their parents’ reach. The fry will emerge from the marbles after about 7 days. At that time or before, parents should either be removed or kept constantly well fed. See the description of breeding techniques in Breeding Freshwater Fish: Barbs. Also, see Fish Food for Fry for information about types of foods for raising the young.

  • Ease of Breeding: Easy

Fish Diseases

Longfin Blue Danios are extremely hardy, and disease is not usually a problem in a well-maintained aquarium. However, the finnage of this variety can be extra sensitive to fin rot and other diseases. Fins may also be damaged during their normal activity. If you notice large tears, you may want to add a fin repair medication. With any additions to a tank, such as new fish, plants, substrates, and decorations, there is a risk of introducing disease. Properly clean or quarantine anything that you want add to an established tank so as not to upset the balance.

These fish are very resilient, but knowing the signs of illness, and catching and treating them early, makes a huge difference. An outbreak of disease can often be limited to just one or a few fishes if dealt with at an early stage. The best way to proactively prevent disease is to give your fish the proper environment and a well-balanced diet. The more closely their environment resembles their natural habitat, the less stress the fish will have, making them healthier and happier. A stressed fish is more likely to acquire disease. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Longfin Blue Danio is readily available and inexpensive. They can be found in pet stores, on the internet, and through mail order.



Featured Image Credit: slowmotiongli, Shutterstock