Roseline Shark (Denison Barb) – Is This Your New Favorite Fish?


Roseline Shark (Denison Barb) – Is This Your New Favorite Fish?

There's no denying there are so many fish options in the aquarium hobby, each offering its own unique charm.

But have you ever daydreamed about having a mini shark in your own space? Lucky for us, the aquarium world gives us freshwater "sharks" that fit just snugly in our homes. No need for an ocean-sized tank!

One great addition to this category is the Roseline shark, also going by the name Denison barb.

Okay, let's spill some tea: they're not the Jaws-type ocean sharks, but who's complaining? Real shark or not, they're super cool to have around.

Not only is the roseline shark perfectly sized for most home aquariums, but it also shies away from aggressive behaviors. So if you want a peaceful community tank, the roseline shark might just be the perfect choice for you!

In this care guide, we'll dive deep into the world of the roseline shark. From their favorite foods to the ideal tank mates, we've got you covered.

By the end, you might just be inspired to welcome this charming 'shark' into your own aquatic haven. Dive in and let's get started!

Roseline Shark (Denison Barb)

Roseline Shark Care Guide

  • Scientific Name: Sahyadria denisonii
  • Common Name: Red Line Torpedo Barb, Miss Kerala, Denison barb, and Chorai Kann
  • Adult Size: 5 inches
  • Temperament: Peaceful; Schooling
  • Lifespan: 5 Years
  • Care Level: Intermediate
  • Water Temperature: 60-77℉
  • Appearance: Torpedo Shaped with Delicate Black, Red, and Yellow Bands
  • Water pH: 6.8-7.8
  • Diet: Omnivorous
  • Tank Size: 55+ Gallons

Roseline Shark Overview

The Roseline Shark, scientifically known as Sahyadria denisonii, belongs to the Cyprinidae family, home to many popular aquarium fish such as goldfish, koi, and barbs.

Dive a little deeper and you'll find its many names such as Denison's Barb, the Redline Torpedo Barb, and get this, "Miss Kerala" - probably because of its vibrant and elegant appearance reminiscent of the colorful celebrations in Kerala, India.

Speaking of India, some folks there call it "Chorai Kanni," which translates to "bleeding eye". Cool, huh?

Now, if you're considering adding this stunner to your tank, heads up! Its care level is termed intermediate. This means that while the Roseline Shark isn’t super demanding, it does need some specific care to truly thrive.

Origin and Natural Habitat

The Roseline Shark, an alluring specimen native to India, can be traced back to the secluded and wild regions of the Western Ghats.

They are naturally at home in the fast-paced waters of rivers and streams, particularly favoring the Achankovil, Pamba, and Chalyar rivers. These have subtropical climates with warm waters and fairly neutral pH values, with the shallow waters surrounded by thick vegetation to provide a protected environment from the bright light bream.

Since the 1990s, the allure of the Roseline Shark as an ornamental fish has skyrocketed its demand, unfortunately putting wild populations in jeopardy. Today, they're considered endangered with dwindling numbers in their native habitats.

Note: To protect the remaining wild populations and ensure the survival of this species, local governments have halted exports.


Now, don't you worry! If you're keen on adding this beauty to your home aquarium, you're in luck!

Despite their low numbers in the wild, they are still widely available in pet stores, and you shouldn't need to embark on a treasure hunt to find one. Thanks to export bans, they're likely born and bred in captivity, ensuring both their survival and their continued presence in the aquarium world!

The cost? You can expect to spend anywhere from $10 to $30, with prices potentially climbing if their wild numbers decrease further.

Typical Roseline Shark Behavior

Roseline Sharks are best known for their active dispositions. They are constantly in motion, flitting about from one side of the tank to the other.

They are medium-sized schooling cyprinids, meaning they are closely related to barbs, rasboras, danios, and even goldfish!

These active freshwater fish are known to move in large schools in the wild, so one is a lonely number for these lively swimmers. For the happiest and most harmonious tank, aim for a school of at least six Roseline Sharks.

Now contrary to some tales, Roselines aren't territorial or “semi-aggressive.” In fact, Roseline Sharks are entirely peaceful, both towards each other and their tank mates.

Male Sharks may spar with each other in bouts for suitors and dominance once in a while, but their lack of real teeth and social nature means these are more like dances than actual fights.

Warning: Roseline Sharks are active swimmers that live in the middle to upper water column. Their speed and skittish nature mean you should absolutely have a tight-fitting lid to the proper tank size because they are known to jump if startled!

Roseline Shark Appearance

Roseline Shark Appearance

The Roseline Shark has an intriguing color pattern that's rarely seen in other fish.

They are almost entirely silver with a black lateral stripe running from nose to tail. Halfway above this stripe, a burst of red bar captures your attention, elegantly fading as it approaches the tail.

The tail itself? A canvas of nature's artistry, adorned with two contrasting yellow patches and stripes of jet black!

But wait, there's more! Mature Roseline Sharks boast a head painted in a shade of emerald green.

Flaring out from their body, delicate fins capture your attention, with the dorsal fin showing a hint of red and the caudal (tail) fin presenting those standout yellow and black patterns.

Their colors are delicate and reminiscent of Painted Glass Fish; thankfully, Roseline Shark colors are 100% authentic!

And for the cherry on top? Their torpedo-shaped body not only grants them the title "Torpedo Barb" but also showcases their built-for-speed design.

How Big Do Roseline Sharks Grow?

Roseline Sharks (Sahyadria denisonii) typically grow to a size of about 6 inches (15 cm) in length when fully mature in aquarium settings.

In their natural environment, there have been instances where they might grow slightly larger. And considering they are both extremely active and schooling fish, it's essential to consider their adult size when planning an aquarium setup to ensure they have enough space to swim and thrive.

Life Span of a Roseline Shark

The typical lifespan of a Roseline Shark (Sahyadria denisonii) in a well-maintained aquarium is around 5 to 7 years.

However, with optimal care and conditions, some individuals might live slightly longer. As with many fish species, their longevity is influenced by factors such as diet, water quality, and overall care.

Tank Setup for Roseline Sharks

Tank Setup for Roseline Sharks

Roseline Sharks might seem easy-going, but they have a bit demanding care when it comes to their living conditions.

These fish thrive under specific conditions, which are a breeze if you've been in the hobby for some time. If you're just dipping your toes into the aquatic world, don't fret! With some research and the right knowledge, you can create the perfect environment for them.

Note: if you're thinking of hosting these aquatic wonders, remember they've got a fine-tuned sense of their surroundings. Even a small change in water conditions? They’ll spot it right away!

These fish flourish when their home feels just right. So, making your tank look and feel like its natural spot isn’t a suggestion; it's a must-do! Here are some general guidelines to follow to get started.

Tank Size

It can't be stressed enough that Roseline Sharks are very active fish.

Thus, the minimum size tank they require is 55 gallons, especially if you're housing a school of 6 to 8 sharks. But think bigger—large tanks of around 75 gallons offer them more room to glide and turn.

You'll be amazed by their speed when feeding time comes around or when cleaning out the tank.

Remember, a spacious tank isn't just a luxury—it's essential for their well-being and yours.

Heads Up: In smaller tanks, Roseline Sharks can become jumpy and might attempt daring leaps. Their acrobatic acts might be a norm in the wild, but it's a heart-stopper at home. To ensure you don't end up with a surprise aerialist, always secure your tank with a tight lid that fits your large aquarium!

Additional fish per gallon

Typically, each of these vibrant swimmers requires a good 6-10 gallons of tank area to glide, dart, and explore freely.

Ensuring this individual space not only promotes their well-being but also showcases their natural behavior in all its glory. Remember, it's not just about surviving, but thriving!

Water Chemistry

Water temperature is one reason why many aquarists fail when trying to keep these fish. Unlike many other tropical fish, Roseline Sharks prefer cooler waters, a trait inherited from their origins in pure mountain streams and rivers.

This cooler environment not only suits their natural habitat but also allows the water to hold more dissolved oxygen, vital for their well-being.

The good news is that Roseline Sharks are adaptable to a variety of conditions. By following the water parameters below, you'll be able to keep your fish healthy for many years.

  • Water Temperature: Between 60°F and 77°F
  • pH Level: 6.5-7.8 (slightly acidic to neutral)
  • Water Hardness: 5-25 dGH

Roseline Sharks are especially sensitive to spikes in ammonia, nitrite, and nitrate levels. Regularly checking the water parameters with a dependable test kit ensures their habitat remains pristine. And don't forget, frequent water changes are a must for their ongoing health.

Water Chemistry

Note: It is generally recommended to perform a 25-30% water change weekly. This helps in maintaining a stable environment and in reducing the buildup of harmful substances.

Plants and Substrate

Roseline Sharks mainly stay in the middle to upper parts of the tank and aren't particularly concerned with plants or substrate, except during breeding.

Hence, the choice of plants and substrate isn't a primary concern for them. However, when designing their environment, they do appreciate certain tank features:

  1. Soft Substrate: Layer the bottom with a soft, fine-grained substrate like sand. Roseline Sharks often hover near the substrate searching for food. Such a substrate ensures they won't get scratched.
  2. Open Spaces: Most crucial for their free swimming and activity. You can use tall background plants like Vallisneria and Amazon sword plants. But keep the midground and foreground open to ensure they have ample space to move around.
  3. Natural Shelter: Floating plants such as red tiger lily, frogbit, and red root floater create shaded areas, giving the Roseline Sharks a sense of comfort and security.
  4. Decorative Elements: Rocks and driftwood can also act as nice focal points for the aquascape but make sure that it doesn't take up too much open water swimming space.

Warning! Ensure your plants and decorations are securely anchored. Denison Barbs are known for dislodging both as they swiftly move through the tank.

Aeration and Filtration

Here's where things can get tricky when keeping Roseline Sharks. These fish are found in nearly pristine mountain streams and rivers. They love strong currents and lots of oxygen. So, in a tank, they need something similar.

Since these active swimmers love to move against currents, a powerhead would make a great addition, especially for smaller tanks.

Aeration and Filtration

Note: Power filters are okay, but often lack the needed flow. Using a powerhead creates a river-like current for the sharks. Make sure other fish have calmer areas to rest; we wouldn't want them worn out by the current!

You've probably caught on by now: Roseline Sharks are picky about their water. They really can't handle stuff like ammonia, nitrite, and nitrate. So, it's crucial to have a top-notch filtration system.

A mature biological filtration system in place is recommended to keep nitrogenous waste products to a minimum. You'll also want to monitor your parameters and perform water changes regularly.

Best Freshwater Fish Tank Mates for Roseline Sharks

Best Freshwater Fish Tank Mates for Roseline Sharks

Roseline Sharks are schooling fish that should be kept in groups of six or more. Given their size and speed, they can make smaller fish species like neon tetras and guppies nervous.

It's better to pair Roseline Sharks with other medium-sized tank mates and peaceful fish like gouramis, angelfish, and rainbowfish.

Dwarf cichlids, while often semi-aggressive, are also a good match since cichlids are bottom-dwelling and tend to focus on each other.

In my home aquarium, Sahyadria denisonii (roselines) get along well with Angelfish, multiple types of tetras, larger guppies, platies, and corydoras catfish.

Keep in mind that although they may peacefully coexist, Roseline Sharks can out-compete other mid-level swimmers for food.

If you're keeping these with peaceful tank mates that feed in the middle of the water column, make sure to provide them with an abundance of food.

Good Tank Mates for Roseline Sharks include:

  • Gouramis, Angelfish, Severums, Geophagus, and other medium-sized Community Fish
  • Giant Danios, Rainbowfish, Silver Dollars, and other medium-sized Schooling Fish
  • Dwarf and Medium Sized Cichlids
  • Corydoras, Plecostomus, and other Bottom Dwellers

A quick heads up: while they're usually peaceful, Roseline Sharks might accidentally hurt really small creatures like dwarf shrimp.

Roseline Sharks Food and Diet

Roseline Sharks Food and Diet

Roseline Sharks are omnivorous in nature and will eat both plant-based foods and animal-based foods.

In the wild, their diet includes insect larvae, small crustaceans, algae, and plant matter.

What Should I Feed My Roseline Sharks?

Bringing a bit of that wild balanced diet into their aquarium life, you can offer them live foods like brine shrimp, daphnia, and tubifex worms. Not only are these foods a treat, but they're also rich in nutrients.

What Should I Feed My Roseline Sharks?

Beyond live foods, frozen foods are also a great choice. They retain much of the nutritional value, ensuring your sharks get a well-rounded diet.

Feeding them foods high in carotene or sprinkling their meals with fat-soluble powders will further enhance their stunning markings and retain their vibrant colors even more. Green vegetables like spinach or broccoli are also recommended.

And for the everyday diet? Small pellets and flakes will do just fine. Just make sure they're high-quality to keep your finned friends in top shape!

Pro Tip: Live brine shrimp, daphnia, and tubifex worms are great choices for newly purchased Roseline Sharks that are unwilling to eat at first. Once they are settled in, you can gradually wean them onto small pellets and flakes.

How Often Should I Feed My Roseline Sharks?

Being so active, you'll want to feed your Roseline Sharks 2 to 3 times per day. Give them enough food for them to eat their fill without any leftovers going to waste.

Remember that Roseline Sharks are quite sensitive to ammonia and other pollutants. So err on the side of caution and feed them lightly at first but for as many times per day as they will feed!

Sexing Roseline Sharks

Roseline Sharks, unlike many tropical fish, are not sexually dimorphic. Meaning, we can't tell the differences between the sexes by looking at them.

Females may be slightly larger and a little less colorful. But these fish can dull or darken their colors based on their mood as well.

If you intend on trying to breed them, which is very difficult to do, you are better off relying on the odds and buying a good-sized school to ensure you get both sexes.

Breeding Your Roseline Sharks

Breeding Your Roseline Sharks

Native to Kerala and Karnataka rivers in India, these denison barbs are thought to be migratory, moving upstream to spawn when seasonal conditions align.

Unfortunately, breeding Roseline Sharks is extremely difficult, to the point of being nearly impossible to do in home aquariums. Although they have been in demand for years now, breeding has proven to be hard to achieve without special conditions.

Since these fish are now endangered in the wild due to over-collecting for the aquarium trade, the Kerala government is currently experimenting with commercial breeders of Roseline Sharks.

Now, while commercial breeders have cracked the code to breed Roseline Sharks with the help of specialized tools and hormones, replicating this magic in your everyday aquarium is a tough nut to crack.

How Can I breed Roseline Sharks?

Captive-bred Roseline Sharks are kept in large outdoor ponds and given hormones when they mature to encourage spawning.

Since this method is impossible for aquarists and you probably don't own a large river with open swimming space for them to migrate in, you're simply going to have to rely on luck.

Small variations in temperature and water levels are known to stimulate many other seasonally spawning fish to breed.

For these fish, you can simulate the spring rainy season with large water changes using distilled or RO (reverse osmosis) water, which drops the pH, salinity, and hardness.

Coupled with a small decrease in temperature, many seasonal spawners will then start to develop eggs and the males become sexually primed.

How Can I Tell If a Denison Barb (Roseline Shark) is Pregnant?

Assuming you're luckier than most aquarists, a female Roseline Shark will swell visibly if she's carrying eggs.

Not so much as a guppy but enough that it will be clear she's preparing to spawn. She will also likely be attended by several males hoping to be chosen as a partner!

While clearly not the easiest fish to breed, this endangered species is possible to condition to spawn.

Frequently Asked Questions

How can I encourage my Roseline Sharks to spawn in captivity?

It's very unlikely that your Roseline Sharks will spawn in captivity. But if you want to try anyway, then keep a few thickly tangled live plants around. A few good spawning plants include Guppy Grass (Naja guadalupensis), Java Moss (Vesicularia dubyana), Hornwort (Ceratophyllum demersum).

Why are my Roseline Sharks losing color?

Answer: A variety of factors, like stress, poor diet, or suboptimal water conditions, can impact their color. Ensure a nutritious diet and maintain a clean, stable environment for them.


Roseline Sharks, with their striking appearance and active nature, certainly add vibrancy to any aquarium. They might be a bit demanding in terms of care, echoing their natural river habitats, but with dedication, they'll flourish in your care!

While breeding them at home remains a challenge, the joy of keeping these active swimmers is rewarding in itself.

Whether you're just diving into the world of aquascaping or have been at it for years, when you treat these fish right, they'll brighten your aquarium in every sense of the word!

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