When people think of sharks, they often associate them with danger and fear. While many species of sharks can be quite dangerous, roseline sharks are not one of them. In fact, roseline sharks are relatively small fish that are known for their beautiful pink coloration. Fast-flowing hill streams and rivers of the Western Ghats in India are home to Roseline Sharks. Roseline sharks are considered endangered species in wild life because of over-harvesting and exporting for fishkeepers around the world. But in 2009, the success of breeding roseline sharks by Chester Zoo had paved the way for the widespread of roseline sharks for fishkeepers.

Overview

Denison barb, Denison’s barb, Miss Kerala, red-line torpedo barb (scientific name Puntius denisonii), but most widely known as roseline shark.

Roseline shark or Denison barb

The roseline shark is a small freshwater fish found in rivers and streams. Orignally from southern India, roseline shark populations have spread to regions such as America, Europe and Southeast Asia.

There was a time that roseline shark was over fished and is now an endangered species. But during 2009, Chester Zoo in UK along with 2 amateur Indian fishkeepers had successfully bred roseline sharks. More than a decade later, roseline sharks are widely found and for sale in the aquarium trade.

The roseline shark makes a great beginner fish and is perfect for those with less experience of keeping an aquarium due to its small size, hardiness, ease of care and adaptability compared to other freshwater tropicals. It can be kept singly or preferredly in groups as it doesn’t seem to come into confrontation with other species but does need plenty swimming space.

Scientific NamePuntius Denisonii
OriginSouthern India
Care levelEasy
Tank levelMiddle
ApperanceBlueish silver or white body
with black & pink stripes
TemperamentPeaceful
Lifespan5-6 years
DietOmnivore
CompatibilityHigh
Minimum tank size25 gallons (100 litres)
Water temperature72°F – 82°F (22 °C – 28°C)
pH levelNeutral
Water typeFresh water

Appearance

The roseline shark is a small freshwater fish found in rivers and streams. Their maximum length can reach up to 7 inches, making them the smallest species of sharks on earth. Their body range from blueish silver to white with a black stripe running from their mouth to tail with pink top fin and sometimes pink tail.

Roseline shark or Denison barb

Puntius denisonii are small but somewhat aggressive predators when hunting for food. Their entire body is covered by rows of dermal denticles or scales which give it an silver armored appearance. The roseline shark has two dorsal fins, one on its head and the other towards the end of their tail.

The most regconizable trait is the black stripe with colorful (usually) pink coloration stripe atop running from its nose through eyes and to the center body. Another strait is the yellow stripe on their black tail.

Gender differences

Male roseline sharks will have smaller body sizes with larger fins, whereas females will have longer bodies and more slender fin sizes.

Natural Habitat & Living Conditions

The roseline shark is a freshwater fish that mainly inhabits densely vegetated areas of slow-flowing streams and rivers. They are found in waters with low levels of dissolved oxygen due to high water temperatures, but can also be found in ponds and ditches near grassy vegetation where they feed on the larvae from mosquitoes or other small insects.

Roseline sharks prefer stagnant soft-bottomed habitats like pools, lakes, ditches, marshes and wetlands that offer them cover from predators as well as food sources such as mosquito larvae. As ambush predators, roseline sharks rely heavily on their camouflage for protection by hiding among plants leaves or under logs when not hunting prey at the surface level.

With an omnivorous diet, roseline sharks will eat just about anything they come across including crustaceans, mollusks and fish.

Roseslione Sharks can be seen from the surface in shallow waters of a canal or lake near vegetation where it is thought that their coloring allows them to blend into their surroundings more easily. They are often mistaken for water lilies when resting on the bottom as well as under rocks or logs with leaves hanging over the edge.

The roseline shark has no known natural predators but does have competition due to its habitat preferences such as other species of ambush hunters like Puntius brevis (swamp barb) which inhabit similar habitats in India’s streams and small rivers. The most common threats to this species include pollution through such sources as agricultural runoff, sedimentation caused by deforestation and direct extraction of water for human use.

In natural environment, their lifespan can be up to 6 years.

Tank conditions

Roseline shark or Denison barb

Roseline sharks are active swimmers that need a lot of space to thrive. Create an environment with plenty of swimming room and a lot of hiding places.

Your tank should be at least 25 gallons for one roseline shark, but the bigger the better if you can provide it. You should always add live plants to create low resting spots for your roseline sharks as well as driftwood or rocks to serve as caves and nooks that will make them feel safe.

Provide lots of different types of water currents so they have something strong enough to swim against but not too powerful where they could get hurt. Stronger currents are found near fast flowing sections in an aquarium whereas weaker currents are found closer to plant roots which produce oxygen during photosynthesis. Your goal is to create an environment so they have a chance to rest and explore without being too stressed.

Your aquarium’s temperature should be between 72°F – 82°F (22 °C – 28°C) with water quality within the range of pH: neutral, KH: 12-15dGH, kH: 0-25.

Read more: Aquarium tank for Roseline shark

Diet & feeding

In an natural environment like a pond or lake roseline sharks feed on plankton and invertebrates that are naturally found in the water column.

Roseline shark or Denison barb

In aquariums, roseline sharks can be fed on a diet of brine shrimp, blood worms and other small invertebrates like water fleas. Because roseline sharks are mid level tank fish, so you can also feed with a wide range of prepacked food such as fish flakes, fish sticks, and pellets.

Read more: Roseline Shark Diet

Breeding

In natural habitat, roseline shark’s breeding season occurs during the rainy season, usually from December to March, but in captivity they can breed all year round.

Breeding roseline shark is not difficult at all as long as you have a good amount of live food that will make it easier for them to find mates and then fertilize eggs or milt. They are considered more egg-layers than live bearers.

The best way for roseline shark to fertilize eggs is by using a “breeding net” or any other object that will create the right environment and surface for them.

In captivity, it’s possible to breed roseline sharks with only one male in a tank of females if there are plenty live food available at all time.

The roseline shark is a live bearer, and the gestation period lasts for approximately two to three months. The size of the fry will depend on how much food mom eats during pregnancy; if she doesn’t eat enough, then her offspring will be small when they are born.

It’s important not forget that roseline sharks are egg-layers, not live bearers.

Compatibility

Roseline sharks are rather peaceful with same sized or largers fishes. Denison barb fish should be kept in groups of at least six so they don’t get too lonely, and may also have less aggressive tendencies.

Other types of fishes that may work well are danios and cardinals. Keep in mind these guys might not want to share their food so you’ll have to feed them individually for some time until they get used to each other’s presence.

Towards other smaller fishes, roseline sharks may also be territorial and may not want to share their territory.

Another thing to keep in mind is roseline sharks are rather vocal. They will squeak, growl, and grunt if they’re not happy with their surroundings.

It’s important that the tank has a number of hiding spots for them so they can get away from any aggression coming their way or take an occasional break from the other fish in the tank. You might even want to consider covering your filter intake as these guys like to have some privacy too!

Some things you can do make sure they feel comfortable include: moving decorations around every now and then; adding live plants as roseline sharks love swimming through leaves; using floating plant covers instead of glass on one side of the aquarium (to block out light).

Verdict

Roseline sharks or Denison barb is an amazing fish to keep in your aquarium. They’re relatively easy to care and feed, they tend to be peaceful with other fishes in a closed system. And because of their colorful body, they’re a great fish to bring life into your tank.

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