If you’re looking to keep brightly colored freshwater fish in your tank, Roseline Sharks are worth their salt.

Also known as the Denison Barb, this species is endangered as its native environment is no longer inhabitable.

Being freshwater fish suggests it’s easy to raise your barbs in nearly any tank model. If well cared for, they can get along fairly well with other fish types inside a communal tank.

Apart from their utter curiosity, Denison Barbs are full of life and fairly easy to feed. Read on to learn more about caring for and breeding Roseline Sharks.

A Brief Review of the Species

Quick Species Facts
Scientific Name SahyadriaDenisonii
Other Common Names Denison Barb, Red Line Torpedo Barb, Roseline Torpedo Barb, Miss Kerala
Family Cyprinidae
Origin Western Ghats, India
Lifespan 3.5 years
Max. Length Around 13-14 cm (5 to 5.5 inch)
Type Freshwater fish

More About the Roseline Shark

The Roseline Shark is a torpedo-shaped freshwater aquarium shark that’s notably colorful compared to most other ornamental fish.

You want to keep it upbeat inside a well-lit aquarium. The tank needs to have all the essential components, which we’ll point out later in this guide.

While its dominant tone is silver, some might have crimson or black hues on their bodies.

Plus, it’s worth noting that the Roseline Shark shares the same descent with noble aquarium fish like barbs, goldfish, carps, minnows, bitterlings, and more.

Denison barbs are endemic to India’s freshwater rivers with high flows as this encourages spawning. They like to dominate the Sahyadri mountain range, commonly labeled as the Western Ghats.

Their demand dates back to the 1990s when dealers imported in mass numbers from India. Subsequently, their population began to shrink.

For this reason, the species was termed endangered. The aquarium hobby market has fairly led to the excessive fall of their numbers in the native habitat.

The Redline shark is now on the  IUCN Red List for being fraught with the possible danger of becoming extinct. On the bright side, these fish are still the perfect fit for hobbyists with huge aquariums.

Besides being brightly colored, Denison barbs are ever active and buzzing.

Habitat, Origin, and History

Like most other schooling fish, Roseline sharks tend to move in large shoals. They find well-oxygenated and clear water such as rivers and streams a lot more habitable.

Other common attributes of where they prefer to dwell include an environment that constantly has a high flow rate, is rocky, and has lots of vegetation.

The fish was found in 1865 in India’s Sahyadri Range, precisely the Achankovil River. In the present day, the species can also be found in the Pamba, Periyar, Chaliyar, Valapattanam, and Bharathapuzha rivers of Western Ghats.

Since the Denison Barb is an ornamental masterpiece, this has led to its overfishing.

And the drop in numbers is a classic example of what happens if a fish in demand is aggressively harvested and held captive. Other aspects like pollution and deforestation are to blame.

While the fish is endangered in its indigenous habitat, some are still sold in commercial breeding stores all across Southeast Asia and Eastern Europe.

Size: How Big Do Roseline Sharks Get?

The typical size of the Roseline shark will hang on several elements that are vital to its optimal growth.

On average, you’d expect the length of your mature barb to be anywhere between 4 and 5 inches. Their modest size and torpedo shape make them grand swimmers.

Some of the features that determine the size of a virgin barb species include the environmental conditions and a few strands of genetics.

When fully grown, the torpedo barb has the potential to reach up to 6 inches in length. This size would make their color more appealing and fun to check on frequently.

To achieve this size in no time, you need to work with a decent-sized tank. Feeding your rose line shark with the proper diet is also a solid pointer to keep in mind.

You’d be surprised how fast they grow as these fish fully develop at a predictable rate. If you’re a pro-aquarist, it’s easy to notice that female redline sharks tend to appear wider and larger. 

Color& Appearance

One headline feature about this species is its long, torpedo-shaped body. It’s all the more reason why other aquarists call it the redlined torpedo barb.

Most barbs have a silvery body. Over the recent past, some hybrids with golden bodies and red stripes without the natural-born black line have been brought to life.

Depending on the lighting, you might also see some native types of yellow or golden shades on their bodies. While they’re fascinating fish to spectate, barbs tend to show some passive aggression towards each other when exposed to bright light during the early stages.

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From the snout to the tail of the Roseline shark, you’ll spot a deep-toned black line. Another feature that contrasts its silver color is a gleaming red line that touches right above the black one, crossing the nose, the eye, all the way to the center of the body.

Its dorsal fins will have a bright red edge, while the caudal fins feature some trails of black and yellow.

During its adult stage, the torpedo barb will develop a pair of barbels that help it search for food. It’s typical for some aging species to have a greenish tint on the head.

What’s Their Life Expectancy?

Aquarists with a soft spot for their ornamental fish would love to keep them for the long term. An estimate from FishBase suggests that your Roseline barb could live up to 3.5 years. However, a study from the Asian Fisheries Society found that the average life expectancy of a redline torpedo barb varies depending on the terrain and natural surroundings on the river. In other words, the habitat generally dictates a barb’s mortality rate. 

Overall, the average lifespan of a Roseline barb will range from 4 to 5 years.

All you need to keep it alive is sticking to the most suitable diet and preserving its environment optimal throughout its lifetime. The other significant detail that contributes to the barb’s longevity is the overall size of the tank.

Keeping them in clean freshwater is also essential when holding them captive.

How to Identify Gender

The prominent feature about fish is that females are noticeably larger than males. However, both will look similar at a tender age.

Most of all, there isn’t any credible study that talks deeply about gender identification. Some aquarists wait till their barbs are ready to mate so they can tell whether a barb is male or female.  

During the mating season, male barbs tend to surround their female counterparts in a circular motion. While it’s fairly challenging to determine the sex of a red line torpedo barb, sexually mature females will have some extra fat around the abdomen. Male barbs, on the other hand, are a bit slender.

Availability & Price

The demand for red line sharks is pretty high as it fascinates many aquarists. You can find baby barbs at your nearest commercial pet store.

Some of the factors that determine the price include the effort put into nurturing the fish, level of genetic improvement, and location. The amount could rise if the population of this species keeps on plummeting.

Prices in most pet stores will range from $10 to $30, depending on the size of the fish. Aside from pet shops, you can find the Roseline shark retailing at $20 each at fish shops or via online sellers.

You’ll find Roseline sharks that have hit maturity and significantly larger retailing at higher margins. Therefore, it’s way cheaper to buy them in groups. You want to scout for redline barbs that are in good shape from authorized dealers.

Complete Care Guide

Quick Care Facts
Care Level Easy
Breeding Egg layer. High success rate if conditions are optimal.
Social Temperament Can along with fish of the same size.
Diet Omnivore
Hardiness Hardy

Best Food for Them

Same as Goldfish, Denison barbs are omnivores. But to keep it chubby and cute, they need a balanced diet. Give them both animal and plant-based meals. Roseline sharks aren’t fussy when fed with a variety of meals.

To enhance the coloration, make sure to feed your Roseline sharks with a diversified diet that’s also densely rich in carotenoids. While in their wild habitat, they were accustomed to feeding on algae, insect larvae, and non-skeletal creatures.

You, however, need to take into account the nutritional value of the diet. Fish food needs to be rich in fiber, protein, natural oils, and more. In most instances, any discoloration on the body of Denison barbs results from poor feeding and an unbalanced diet.

Pellets, flakes, and other dried feeds are suitable for captive Roseline sharks. They’re inexpensive, readily available in the market, and don’t need too much preservation. However, if you’re not on a strapped budget, live or frozen meals are a more viable option since they’re not processed.

As a result, they’ll hold more nutritional value. You can feed your fish with live meals such as brine shrimps or bloodworms. It’s worth noting that any waste food would contaminate the water and lead to rotting.

To mimic its natural diet, you can feed the barb with vegetables such as finely chopped spinach or broccoli. Roseline sharks also naturally prey on insects. We recommend feeding your barbs at least 2 to 3 times a day with small meals, rather than one large portion once a day.

Temperament &Behavior

Compared to the infamous aggressive sharks, Roseline barbs are known to be pretty harmless, and they get along reasonably well with nearly all other living beings inside an aquarium.

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However, that’s not to say they can’t be agitated. You might infrequently see them bicker with other members in the tank. If the tank space is large enough, they’ll hardly become aggressive.

When kept together with naïve fish, Roseline sharks might make a lot of noise for them and contribute to their anxiety since they’re quite energetic while swimming.

On the bright side, this makes them fascinating to watch, not to mention their habit of moving in shoals. If left in solitude, barbs will show some tendencies of being lonely.

Roseline sharks are only hostile if there isn’t enough room to swim. Being fast swimmers, they’re likely to cause trouble when living with slow fish. When competing for food, Denison barbs might also irritate timid fish like Nanos or Discus.


There needs to be enough space for spawning to breed Roseline sharks effectively. You would need high-flow rivers, which is somewhat impractical. The chances of breeding barbs held in captivity are pretty slim.

While commercial entities can achieve a higher success rate, breeding your barbs at home isn’t common. Most commercial breeders have better chances since they use high-tech systems and infuse the breeds with hormones.

Since the early 2000s, scientists have begun to induce the reproduction of Roseline sharks held in captivity using the Ovaprim hormone. There aren’t any known methods to enhance natural reproduction among fish.

Without leveraging the perks of spawning, it’s difficult to breed your barbs at home.

Ideal Conditions for Spawning

Like Goldfish, the Roseline shark lays its eggs in the water bed. While spawning might induce the laying of eggs, this is most effective when the barbs are moving in groups of 15 or slightly higher. 

A report from the Indian Journal of Fisheries found the ideal season for spawning redline torpedo barbs in their native habitat was from November to March.

This study notes that the age and size of the breeding couple determine their ability to produce new offspring. Plus, hatching takes place after 36 hours of fertilization. During this stage, the water temperature needs to be about 27.5 °C.

To boost the rate of spawning, you want to lower the overall pH to about 6.5 in a gradual manner. If the vegetation inside the tank is dense, it’s much more convenient for the fish to lay and protect their eggs.

The Indian fern, moss, and hornworts are some of the suitable plants for your breeding tank. Keep the temperature levels between 15 to 24 °C. Once the egg-laying phase is over, keep the parents away from their eggs.

After hatching, they’re rich in protein and iron, and the parents, as well as other adult fish, might prey on them.

 Once the larval stage is over, you can feed your baby barbs with brine shrimps, also scientifically known as Artemia nauplii. They’re easy to digest and help speed up the growth rate.

This study implies that hatchlings fed with micro worms live longer. It also discovered that a dose of Ovaprim at 0.5 mL/kg of the body and weight of females and half of the same dose for males can be used to breed Denison barbs.

Common Diseases

Many aquarists love to keep the Roseline shark as a gorgeous ornamental fish. Failing to take proper care of its living conditions could cause the Denison barb to suffer from many health issues.

There aren’t any specified diseases that this species is susceptible to. Still, it’s prone to conditions that often affect freshwater fish. If the water quality deteriorates over time, this might be a health hazard to your Roseline shark.

Here are some diseases that this species is likely to suffer from for failing to care for its environment properly. 

Fungal Infections

Fungal Infections are hard to treat as they tend to have similar symptoms. They belong to a huge family made of different species and symptoms. For this reason, it’s easy to mistake some fungal diseases for bacterial conditions as the symptoms might appear similar.

Using Ich X to treat both infections can be an effective solution. Also, make sure to isolate the infected barb and treat the water using antifungal remedies.

You can tell if your Roseline shark is suffering from a fungal disease if it has some cottony growths on the skin, fins, and around the eyes. Some of the triggers include prior injury, stress, or contaminated water.

White Spot Disease

White spot is a parasitic illness that primarily affects fish. It’s caused by Ichyophthiriusmultifilis, often labeled as Ich, and preys on Roseline sharks’ bodily fluids and cells. They hide in pond trash and reproduce pretty fast.

Any behavioral change you might notice on your barbs could be a sign they’re infected by this disease. Your fish will start rubbing against the stones on the base part of the tank.

To keep the parasites at bay, you can add some zinc-free malachite to the tank. Before introducing any new fish to your aquarium, it’s best to quarantine them for at least two weeks.

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Tank Recommendations

Quick Tank Facts
Water Temperature 68°F – 77°F
Minimum Size 55-gallon, 4 ft length tank
Water Hardness  5 to 25 dGH
pH Level 6.8 to 7.8
dH Level 5-25

Tank Size Requirements

Roseline sharks need enough space to coexist with other fish species. Adults will also grow a bit larger and are somewhat more energetic swimmers.

If you have extra room to spare, it’s worth it to use a larger tank. Pick one that can hold at least 55 gallons.

When looking to adopt a small school, this tank size would suffice. The goal is to have 6-10 gallons of swimming space for every barb.

What to Include When Setting Up a Tank


You can accessorize the fish tank using natural living plants. By far, this is a harmless way of adding oxygen to the tank.

Aside from feeding your Roseline shark with nitrogenous waste, the plants help cleanse the water. Background plants such as Vallisneria (Vallisneria spiralis) and Amazon Sword plants (Echinodorus sp.) are low to the ground, allowing the barbs to swim freely.  


Pick an LED lighting system that’s ideal for both your Roseline sharks and plants. Your red line torpedo barbs need some to absorb thermal heat, which improves their wellbeing and speeds up the rate of metabolism.


Roseline sharks tend to feed on algae and soft-bodied plants at the base of the tank. Therefore, adding a substrate made of shell-shaped stones and sand would be a brilliant idea.

You can make a cave-like layout that the burbs can use as a hideout for safety. It’s also essential to use materials that won’t cause injuries to your torpedo sharks.

Filtration & Oxygenation

Being a freshwater fish, the Roseline shark is fond of aquariums that are cleansed at frequent intervals. Filtering toxic gasses like ammonia by adding beneficial bacteria would help lengthen your barb’s lifespan.

Roseline sharks like swimming in all directions, including the tank’s base, so oxygenation is equally essential. You can use water bubblers to scale up the level of oxygen in the aquarium.

Water Parameters

Right from their native habitat, Roseline sharks are known to dwell in streams and rivers that are well-oxygenated and have dense plant growth. You need to tweak the water parameters inside the tank so it can accommodate your barbs.

These fish can tolerate slight fluctuations. After hatching, the temperature inside the tanks must constantly be kept in the range of 70 °F (25°C). Make sure to avoid using water that’s alkaline as they like to live in relatively hard water.

You also want to reduce the nitrate levels to almost 0 ppm. Make sure to keep the pH anywhere between 6.8 and 7.2. We recommend replenishing about 30% of the water volume at monthly intervals to keep your redline torpedo barbs far from harmful pollutants.

If you’re a newbie aquarist, it’s crucial to note that chlorine can be detrimental to the health of your Roseline sharks. Some other water treatment options often sold in aquarium supplies stores could also contain heavy metals, which are harmful if in high compositions.

Therefore, it would be best to use an antichlor agent to weed out any excess chlorine when replacing water in the tank.

Suitable Tank Mates

Keeping Roseline sharks in isolation could induce their stress levels as they’re social and need to be in a group so they can thrive. You can keep a half-dozen of different fish in a fairly large tank.

Fortunately, there are a bunch of options that are compatible and can coexist with the red line torpedo barb. You want to match them with those nearly similar in size and speed while swimming.

Better still, you can pick fish from the same species that are pretty active and have sturdy fins. When choosing their tank mates, it’s worth noting that Roseline sharks don’t like being around lazy and feeble fish.

Here’s a list of compatible tank mates:

  • Tiger Barb
  • Cherry Barb
  • Rainbow Fish
  • Odessa Barb
  • Kribensis Cichlid

To keep their stress levels low, make sure your barbs aren’t overcrowded. If you have enough space, opt for a reasonably large tank.

Helpful Tip: Before choosing which tank mates to include, it’s worth noting that keeping different fish types of a similar genus or species might lead to hybridization.

Frequently Asked Questions

Are Roseline sharks hardy?

Roseline Sharks are generally robust and hardy, but they require clean, crystal clear water to thrive. They’ll become anxious if the water is muddy or unhygienic, making them vulnerable to common infections.

Do Roseline sharks go to school?

They certainly do! A school should have at least six sharks, but more is always ideal. Roseline sharks create schools of hundreds of fish at a time in the wild when moving from one region of the river to another. As a result, producing them in captivity is pretty tricky.

How do I know if my Roseline sharks need more oxygen?

If your sharks are gasping on the surface, that’s a hint they’re in need of more oxygen. They’ll also start to hang around the filter output as this area tends to have a higher oxygen concentration.

Final Thoughts on Caring for Roseline Sharks

With so many colorful ornamental fish in the market, it can be difficult to know which to pick for your tank. Roseline sharks are well-liked for their lively nature, but they need a large tank since they need extra space for swimming.

While breeding them might be a challenge, they’re a perfect option if you’re looking for a species with a basic caring routine.

Most aquarists can nurture the red line barbs without facing major hurdles if they can keep them in clean, well-oxygenated water.

About the Author

Shirlie Sharpie

Shirlie is an aquatics expert with nearly two decades’ experience raising and caring for ornamental fish. She has produced a book on aquarium setup and a slew of fish-related articles. Her expertise has been recognized by organizations like the Minnesota Zoo and the National Aquarium, where she has worked on notable initiatives.

Career Highlights:

Educational Highlights:

  1. Attended Argosy University Twin Cities.

Writing Experience

The marine life lover Shirlie has written hundreds of articles about fish and teamed up with public aquariums & nonprofit organizations to create content. She’s contributed aquatic information for almost 20 years writing for‘The Spruce Pets,’and has also worked for FAMA, the FishBase, and “Ask Heloise show.”

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