You are currently viewing Denison Barb (Roseline Shark) : Best keeping guide 2021

Denison Barb (Roseline Shark) : Best keeping guide 2021

Denison Barb is a stunning freshwater fish with a peaceful, active personality. This eye catching fish is native to Southern India.

Actually, this fish is a new addition to the aquarium hobby. Therefore we can say one of the most expensive and shoaling fish in this hobby.

Unfortunately, this great shoaling fish is currently listed under the endangered list in IUCN red data book. The main cause for this is the overexploitation and high demand from all over the world.

Sometimes the difficulty in breeding in home aquaria may affect this.

This fish was first described by Francis day, and it was named after Sir William Denison. This beautiful fish belongs to the family Cyprinidae and the genus Sahyadria.

Therefore correct scientific name of Denison barb is the Sahyadria denisonii. Why I say as the correct name, earlier it was identified by several other scientific names they are,

  • Labeo denisonii
  • Barbus denisonii
  • Crossocheilus denisonii
  • Puntius denisonii so on.

Source Wikipedia:

Sometimes you may also still use these names as synonyms.

You must need to pay attention to the Denison barb because it requires a large aquarium space(the later part, I will discuss more about that).

Under this article, I will cover all the details regarding the keeping, breeding, feeding, characteristics, origin, so on. Keep reading!

  • Optimum temperature = 60-77 Deg F 
  • Hardness of water = 5-25 dGH
  • Scientific name = Sahyadria denisonii
  • family = Cyprinidae
  • Origin = South India
  • Care = Easy
  • Minimum tank size = 55-75 gallons 
  • pH = 6.5-8
  • Diet = Omnivore 
  • Size = 5-6 inches in size


Even though this freshwater fish named Denison barb has several other names as well, they are

  • Roseline shark
  • Miss Kerala ( it shows originate from India)
  • Redline torpedo barb
  • Denisons flying fox
  • Red comet barb
  • Bleeding eye barb

So now hereafter, you can call this fish from any name you like.

Denison barb? Roseline shark origin and distribution

As I told you earlier, this exciting fish is native to Southern India. Currently, the majority of fish export to the world through Calicut, India.

Roseline shark is endemic to Kerala and Southern Karnataka, where the Pamba, Chaliyar, and Achenkovil rivers belong.

It also can be seen in wildlife sanctuaries such as Periyar, Travancore, Mundakayam, and Kallada. This fish is mostly found in hill streams, rivers, and ponds that contain a high amount of oxygen and high vegetation.

Therefore you can imagine how it got the name, Ms. Kerala. You can also use “Chorai kinni” which has the meaning of bleeding eye, to name this fish.

First, Denison’s barb was introduced to the world from an International aquarium exhibition called “Aquarama,” held in 1997.

After that, within a decade (literally within a short period of time), this Roseline shark became popular worldwide. As a result of high market demand, the population dropped due to over catching the fish to export.

There are other reasons as well, deforestation by cutting trees around the river banks was the main reason to reduce the population due to loss of vegetation within the rivers.

Another cause is rivers get polluted with contamination of household and agricultural wastewater, which contains many fertilizers and detergents.

However, it is still listed as an endangered species under IUCN red data book.

Aquarists all over the world are currently trying to breed this amazing fish in captivity but still record only accidental breedings.

Denison barb appearance

Roseline shark or Denison barb has a very bright color silvery body with prominent several other colors. The name Redline torpedo barb shows this fish has a torpedore shape streamlined body that looks like a shark.

Bright red and black markings can be identified on the body.

There is a black stripe running along the body from snout to the tail. You can also observe scarlet lines (bright red lines) that run parallel to black stripes, originated from the nose, and run via the eyes to the body’s center.

Also, can see bright scarlet on the dorsal fin as well.

Some Denison barbs have an emerald green hue on top of the eyes, and in the caudal fin, there are bright black and yellow stripes.

Finally, I can say that these red and black markings make the fish more beautiful. When we compare the male and female Denison barb, you can not identify a big difference between them.

Only thing Roseline shark females have a slightly faded color with respective to their counterpart males. And females grow slightly bigger than males.

Denison barb lifespan

This beautiful fish has an average lifespan of 5 years in captivity. It varies on how you care for. Better to provide all the required conditions at an optimum level.

Denison barb size

Typically this great shoaling fish has an average size of 5-6 inches(15cm) in the wild. Many of them grow up to about 3.5 -4.3 inches (9-11cm) only when it comes to captivity.

Denison barb care and habitat: Setting up the inside of the tank

The most important thing you must keep in your mind regarding the Roseline shark is that these fish are from highly oxygenated water streams containing rocks and lots of natural vegetation.

When preparing your aquaria, it is necessary to give them with same natural habitat conditions. Otherwise, it can lead your fish to stress and susceptible to various diseases, and even color may get lost.

So providing adequate hiding places for these fast swimmers is essential. You can use driftwood, bogwood, various rock caves, and live aquarium plants to decorate the tank.

It is better if you choose sand, fine gravel, smooth rocks, or pebbles as the suitable tank substrate.

When considering the live aquarium plants, it is better to go with Anubias, Hornwort, Pennywort, Vallisneria, Java moss, Java fern, Bacopa sp, Cabomba so on.

Be sure you cover the stems of plants properly with the rock piles; otherwise, these fast swimmers can uproot it.

Note: Be sure not to overcrowded tank space with lots of decorations because Denison barbs are highly mobile and need more swimming space.

Another most important thing is covering the tank with a lid; why am I saying this? As Roseline sharks are highly active can pile off/jump out from the tank.

That is why I told not to overcrowded with too many decorations.

Here are some brief details about aquarium plants that can be use to decor Denison’s barb tank inside.

Hornwort = Plant, which belongs to the family Ceratophyllaceae and a group of bryophytes.

This plant prevents the formation of algae within the tank and keeps water oxygenated. It requires a pH of 5-8 and temperature of 63-86 Deg F, and a water hardness of 2-25KH.

Java fern = This plant belongs to the family Polypodiaceae and an easy growing plant that grows up to about 13.5 inches. Also, plant doesn’t require any CO2, fertilizer, lighting very much.

It will create an underwater forest so quickly.  Is an excellent aquarium plant for a Roseline shark tank. It needs a pH of 6-7.5, a temperature of 68-82 De F, and a water hardness of 3-2 KH.

Cabomba = This aquarium plant belongs to the family Cabombaceae. A very good plant which helps to maintain a high oxygenated tank.

But remember, this plant requires a lot of lighting. Therefore optimum pH level is around 6.8-7.5 and water temperature is between 72-82 Deg F, water hardness is around 3-12 dKH.

Denison barb tank size

Roseline sharks are great shoaling fish which like to swim together. As I told you earlier, these active fast swimmers need enough swimming space to mobile quickly without any obstacles.

Therefore minimum Denison barb tank size is around 55 gallons. So choose and wisely invest in tanks that are longer rather than very tall. In other words, tank length is important than tank height.

Water quality parameters

Already you know that Denison barbs are from the highly oxygenated hill areas in Southern India. Therefore providing the natural ambient water conditions is a must.

Even though Roseline shark tolerate a wide range of water conditions prefer cold water conditions very much.

Frequent changes in water temperature should be avoided. Mainly it can lead to suppressing the immunity of your fish.

Therefore required optimum water temperature is between 60-77F ( upper limit temperature of 78F is okay). The optimum pH level is around 6.5-8. Water hardness should be between 5-25 dGH.

You also can use a water test kit to monitor the water conditions regularly. Better to change water; otherwise, ammonia and nitrate levels can hit your fish health. I hope you get the point.

  • Water temperature – 6077F
  • pH – 6.5-8
  • Water hardness – 5-25 dGH


We all know that Denison barbs are from habitats having a high water flow and oxygen level, So we need to give the natural water conditions in home aquaria as well.

For that, you can use a canister water filter, submersible jets, and other internal power filters to provide good filtration. You can arrange these filters pointing towards down along the length of the tank.

It will help create a good water flow along the tank’s length and make water rich in oxygen.

Denison barb tankmates

These fish are good shoaling fish so need to keep as groups. It is very nice to see when Denison barb school highly actively swim together.

You can keep Roseline shark/Denison barb as a group of 6 or more. If you keep a single fish, it can be stressed to avoid that you can use the following tankmates as well.

  • Tetras
  • blood parrots
  • Angelfish
  • Danios

Barbs such as,

  • Odesa barb
  • Cherry barb
  • Rosy barb
  • Tiger barb
  • Rainbowfish
  • Apistogramma, so on.

Denison barb food

These fish are omnivores eat whatever you feed. What do Roseline sharks eat at natural habitat?

They survive on large algae and other insects within the natural habitat, invertebrates among the rocks and the substrate.

When it comes to the aquaria, quality feeding is very important for conditioning the fish at breeding and to have a vibrant coloration.

Aquarists say that better to feed these fish with a balanced diet rich in carotenoids and astaxanthin pigments, which will improve as an intense coloration.

In-home aquaria, you can feed your fish twice a day with the following food,

  1. Bloodworms
  2. Cyclops
  3. Brine shrimps
  4. Algae 
  5. Spirulina
  6. Daphnia
  7. Artemia
  8. Flake foods etc.

Even you can give freshly blanched vegetables as well. So there is a different kind of food, be sure not to overfeed.

It is advisable to give food that can eat within about 2 minutes, overfeeding dirt the tank, and make your fish unhealthy by lowering water quality.

How to say Denison barb male or female?

As I told you earlier, there is no big difference between male and female fish. But the following characteristics variate from female a male.

  • Size – Females are slightly larger than males.
  • Color – females have a faded color compare to males.
  • Body – Females also has a heavier body compare with counterpart males.

Denison barb/ Roseline shark breeding

One of the hardest parts is breeding because this fish cannot breed in captivity, except for rarer or accidental cases.

That can be the main reason for high demand and high price. But in commercial farms, many aquarists have tried, and two successful breedings reported.

One is German aquarists who successfully spawn 15 of Denison’s barbs with the use of hormones. Their females laid eggs on the aquarium plants within the tank.

The second report is from an England zoo called “Chester Zoo” this was reported as accidental breeding.

Thereafter, second spawning was carried under the control conditions using soft acidic water around pH 6 and GH 2-3.


Are Denison barbs aggressive?

Generally, we say these fish have a peaceful behavior. But sometimes it can become slightly aggressive due to the following reasons.

When trying to maintain a hierarchical position among the schooling, fish tend to behave aggressive.

Another thing is if you are not given enough swimming space, Denison barb tends to show aggressive behavior.

So wisely invest in a tank with a minimum tank size of 55 or 75 gallons. Avoid overcrowding with aquarium decorations.

These Roseline sharks are fast swimmer, and there you need to keep with the fast swimming tankmates.

If keep with slow swimmers, accidents and injuries can happen.

Another important thing these Denison barbs are not fin nippers.

You can keep even with fish having long flowing fins such as plecos, goldfish, which will produce a good biotype community tank.

Note: Slight aggressive behavior can avoid by keeping as groups of 6 or more (approximately 8-10 species are okay to go with)

Possible Denison barb Diseases

Normally Denison barbs are hardy but can susceptible to various other common diseases. Before that very important to keep in your mind that natural habitats have very clean and clear water.

So home aquaria also need to be clean and clear.

There may accumulate food waste; you can remove those by using a vacuum pump, fixing a good filtration system, and regular water change.

Let’s see Denison barb diseases.

Columnaris – One day, I observe one of my Denison barbs has a blue bulge developed in its body. I thought it was a fungus or any other parasite.

There I found it was not a fungus or parasite, a bacterial disease caused by aerobic gram-negative bacteria called Flavobacteria.

The prominent thing about this bacteria is it causes the disease in tanks having high oxygen levels and clean tanks with low organic matter; how unfair it is.

Once you identify, you need to quarantine all of your fish because it spread fast among other fish as well.

Other reasons to arise Columnaris is overcrowding, rough handling, stress due to frequent change of water temperatures (mostly high temperatures affect this,)


Aquarists say it is difficult to identify symptoms in fast swimmers like Roseline sharks.

But there may you can observe fish gasping at the water surface, ventral and pectoral fin areas become bloated,

Even body color can be faded.

Treatments: You can use antibiotics such as Kanaplex and nitrofurazone.

Note: Use veterinarian advice if you do not know how to use antibiotics)

The second way of treatment is using any un iodized salt recommended for this, such as kosher, sea canning salts, aquarium salts.

Anyone can easily use this method.

There it would be best if you used 1tbs of salt per gallon of water. It is useless if you use 1tbs per 4-5 gallons, be aware!

So you need to use 2 doses in 12 hours apart period. Repeat the other two extra 12 hours until your fish turns to normal behavior.

Ich disease – This is a common fish disease among most freshwater fish species. There small white dots develop all over the fish body.

To avoid that, keep your fish with minimum stress by maintaining good water conditions and giving a quality diet.


I think peaceful, active behavior and personality may be a reason to enter aquarium hobby as an exciting species with high demand all over the world.

Maintaining good water parameters is the most important thing to be considered when keeping Denison barbs or Roseline sharks.

I hope this article will guide you to get your fish’s maximum benefits that you are expecting. Happy fish keeping.!


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