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

Are you looking for an exciting fish to add to your freshwater aquarium that will get along with its tank mates? Then why not consider the Roseline Shark (otherwise known as the Denison Barb, Red Line Torpedo Barb, or sahyadria denisonii)?

This gorgeous fish is a great addition to any tank — it has striking colors, interesting behavior and its active personality will brighten up your tank! Plus, when cared for properly, it can make a fantastic pet that lives happily in captivity for many years.

In this post we’ll share everything you need to know about caring for these stunning freshwater fish so that you can decide whether or not they are right for your tank.

Roseline Shark Care Guide

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!

Since they are a little on the uncommon side, there’s quite a bit of misinformation surrounding this fish species behavior that we’re going to clear up right away in this roseline shark care guide. For starters, Roselines aren’t territorial or “semi-aggressive,” as some care guides assert. 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.

Roseline Sharks are active freshwater fish that live in the middle to upper water column. Their speed and skittish nature means you should absolutely have a lid fit to the proper tank size because they are known to jump if startled!

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 stripe running from nose to tail. A brilliant red bar runs for half of that distance above the black stripe, and two yellow patches on their tails completes the picture.

Their colors are delicate and reminiscent of Painted Glass Fish; thankfully, Roseline Shark colors are 100% authentic! The body of these fish is fitting for their other common name (Torpedo Barb). Roseline Sharks are built for speed and grace!

Life Span of a Roseline Shark

Roseline Sharks have a middle of the road life span. 5 years is considered an average life for a Roseline Shark, with 1-2 years in either direction not uncommon.

How Big Do Roseline Sharks Grow?

As medium sized community fish, Roseline Sharks grow to be 5 inches long. Both males and females grow to be this long. And considering they are both extremely active and schooling fish, you’ll need slightly more space than you’d expect for a Roseline Shark.

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.

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 tank mates 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) gotten 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.

Despite the fact that Roseline Sharks are peaceful fish, you should not keep them with dwarf shrimp or other species that are too small that they can’t help but injure.

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

Habitat and Water Quality for Roseline Shark Care

Roseline Sharks are from India – the native population tends to live in very isolated places in the wild.

Wild roseline shark populations specifically come from the Achankovil, Pamba, or Chalyar rivers. These have subtropical climates with warm waters and fairly neutral pH values; population numbers have declined but are trying to help them to get better. Roseline sharks live in shallow waters with many rocks surrounding thick trees which provide a protected environment from the bright light beam. This means the addition of fine gravel will likely help to replicate the tank water and habitat the denison barb is used to.

Since Roseline Sharks are found in tropical environments at moderate elevation, the water temperature can reach up to 80℉, yet 72-78℉ is more common for them. Water temperature is one reason why many aquarists fail when trying to keep these fish; Roseline Sharks need to remain slightly cooler than other tropical fish. Cooler water can also hold more dissolved oxygen (see below).

Roseline Sharks prefer tanks with lots of shelters, like live plants and driftwood to replicate their natural habitat. In my tank, they spend a significant amount of time swimming again the current created by a powerheard. These active swimmers require plenty of swimming space, so if you have a smaller tank size a powerhead can replicate the flowing current of their natural habitat.

Water Chemistry

Here’s where things can get tricky when keeping Roseline Sharks. These fish are found in highly oxygenated, nearly pristine mountain streams and rivers. They have a very low tolerance for elevated levels of ammonia, nitrite, and nitrate. This means that you’ll need a mature biological filtration system in place to keep nitrogenous waste products to a minimum. You’ll also want to monitor your parameters and perform water changes regularly.

Roseline Sharks also need both current and high levels of dissolved oxygen. Current gives them flow to fight against and turns over the water column enough that oxygen levels remain high. Since power filters rarely provide enough flow you’ll want to set up a powerhead on one end of the tank.

This way, you can provide a river-like flow environment for your Sharks. Just make sure your other fish don’t mind a constant current or they have areas of no flow they can escape to. We don’t want slow swimming fish to become exhausted by the powerhead.

Tank Setup

Roseline Sharks are pretty sensitive to any water quality changes and require pristine tank conditions at all times. Regular partial water changes and good filtration is recommended to keep them healthy and happy in their tank environment.

Tank Size

It can’t be stressed enough that Roseline Sharks are very active fish. This means we need at a minimum, 55 gallons of space for a school of six to eight Sharks, with 75 gallons being even better as the width gives them some more turning space. You’ll be amazed by their speed when feeding time comes around or when cleaning out the tank.

A larger tank also gives Roseline Sharks space to maneuver when you’re performing tank maintenance. Because the last thing you want is for one to try launching itself out of the water. While this works well in nature it can end up with a fish on the floor at home, which is stressful for both you and the Shark! A secure lid is therefore a must.

Plants and Substrate

Plants and substrate choices aren’t too important to Roseline Sharks since they don’t bother plants except when breeding and they are middle to upper water column dwellers. Open space is much more important for them. You can certainly use tall background plants like vallisneria and amazon sword plants.

But keep the midground and foreground clear of tall plants as they will only get in the way. Floating plants like red tiger lily, frogbit and red root floater can also provide shade and a sense of security for Roseline Sharks! 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.

It’s very unlikely that your Roseline Sharks will spawn in captivity. But if you’re wanting 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)

By following the water parameters above, including the proper tank temperature, water hardness, and tank water conditions, you’ll be able to keep your fish healthy for many years.

Feeding Your Roseline Sharks

What Should I Feed My Roseline Sharks?

Roseline Sharks are purely carnivorous in nature and will eat both live and frozen foods in an aquarium. However, they feed on plankton and small invertebrates like insect larvae, water fleas and blood worms. They are known as “micro predators” since they feed only on tiny animals. In this case, blanched vegetables or green vegtables will be something you’ll need for other shoaling fish in your community tank.

Many of the items needed for eating can be found in the fresh and frozen sections of your local fish stores. Live brine shrimp, daphnia, and tubifex worms will all be happily accepted and 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, if they aren’t already eating these.

Make sure you read the ingredients label and choose a brand that has animal protein as one of the first few ingredients. Many cheap fish food blends use wheat, potato starch, and other low quality fillers that offer no nutrition whatsoever to carnivorous fish. Fish meal, shrimp, insect larvae, and other high quality fish food ingredients are what Roseline Sharks need in their flakes or pellets!

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!

Breeding Your Roseline Sharks

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.

It’s believed that this freshwater species of denison barbs are migratory fish in the native rivers of their natural habitat in Kerala and Karnataka, India. They likely follow seasonal cues to head upstream and spawn en masse when the temperatures and water chemistry is just right. 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 to satisfy the aquarium hobby’s demand for these beautiful fish.

How Can I breed Roseline Sharks?

Captive bred Roseline Sharks are kept in large outdoor ponds given their active nature and hormone treated once sexually mature. The hormones stimulate the fish to spawn, regardless of where they are located or the time of year.

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, one 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 Big Do Roseline Sharks Grow?

5 inches is the norm for Roseline Sharks. Just remember that being as fast and social as they are, they need more space than most fish their size. 55-75 gallon tanks are perfect for them.

Is The Denison Barb a community fish?

While not generally considered a community resident given their large size and ability to live with semi-aggressive species, the Roseline Shark (sahyadria denisonii) is generally a peaceful fish that will get along with others ina proper shoal. While beginner aquarists should always be careful keeping big fish with smaller fish to prevent and injure fish, with room to swim freely and plenty of plant life your mixed community tank should get along swimmingly.

Are Roseline Sharks schooling fish?

Yes, denison barbs are schooling fish and will do best when kept in groups of 5 or more. Schools of 10-15+ individuals look particularly impressive! They should be kept with other active species such as barbs, danios and rasboras to keep them company.

What to feed Denison Barbs?

Roseline Sharks should be offered a variety of high quality sinking pellets, live foods such as worms and crustaceans, and frozen foods like artemia or krill. Variety is key to promoting their natural diet in the wild!

Have more questions?

If you still have questions or would like to show off your tank, be sure to like our Facebook Page!

Frequently Asked Questions

How Big Do Roseline Sharks Grow?

5 inches is the norm for Roseline Sharks. Just remember that being as fast and social as they are, they need more space than most fish their size. 55-75 gallon tanks are perfect for them.

Have more questions?

If you still have questions or would like to show off your tank, be sure to like our Facebook Page!