Roseline sharks, or Denison barbs, are an active, attractive species of freshwater fish that makes a lovely addition to any fish tank. They have pretty straightforward needs, but they are more suited to intermediate-experienced aquarists who can take care of them well and maintain the larger tank size they require.

These little – okay, not so little – beauties add some bright color and energy throughout as they swim about.

Let’s take a look at these peaceful fish and learn all about their care, history, needs, and maybe even a few fun facts.

Quick Intro to Roseline Sharks

Family: Cyprinidae
Scientific Name:Sahyadria denisonii
Common Names:Roseline Shark, Denison barb, Red-Line Torpedo barb, Miss Kerala
Care Level:Intermediate

Natural Habitat, Identification, and Where to Buy

The Roseline shark hasn’t been in the fishkeeping industry for very long, despite having been discovered in 1865. The fish natively lives in the Achankovil River, Cheenkannipuzha, near Mundakayam town, and in the Chalivar River, in the Weston Ghats. They weren’t imported for fishkeeping until about 1990!

Immediately, the popularity in the fishkeeping hobby decimated the species along with the local deforestation. The fish have been since and remain now on the IUCN Red List marked as a “decreasing” species.

Commercial breeders have programs now, however, in both Southeast Asia and Eastern Europe to help the fish rebuild population and be freely available for fishkeeping enthusiasts. Wild collection of the Denison barb, however, remains greatly restricted.

The fish lives in large shoals in streams, pools, and rivers where the water is highly oxygenated and clear. These rivers and pools are rocky and densely vegetated and have high flow rates.

Denison barbs have long, torpedo-shaped bodies in silver with black lines that extend the length of their bodies. They also have a bright red line that runs along the top of the fish’s black line to the midpoint. Their dorsal fins are edged with vibrant red, the caudal fins with black and yellow stripes. When they’re mature, they also have a bit of greenish hue on their heads.

Thanks to breeding, there are also specially hybridized varieties with gold and red lines instead of the black stripe.

Roseline sharks reach about 6-inches in length at full maturity.

If you’re ready to purchase one of these lovely, sparky fish, you can find them at many locations online, including:

Optimal Water Conditions for Roseline Sharks

Water Temperature: 60 to 77 F
Water Flow Rate:High flow rate
pH:6.8 to 7.8
Water Hardness:5 – 25 dGH

Tank Setup

Minimum Tank Size: 55 gallons
Optimal Tank Size:75+ gallon tank
Optimal Tank Shape:Long rectangle
Recommended Filter Type:High powered filter, ideally canister filter with a powerhead

The Roseline shark lives in an environment that naturally has a fast flow rate. They also need pristine water – so a powerful filtration system (we recommend a canister filter and a powerhead working in conjunction with each other) is required.

This fish species also require highly oxygenated home aquariums, which is part of why a powerhead is recommended. They need plenty of plant life (we’ll talk about that later) and the water parameters guarded carefully, especially with all those plants.

This freshwater tropical fish needs temperatures between 60 and 77 degrees Fahrenheit, ideally closer to the warmer side of that range. They also need a pH range of 6.6 to 7.8, with a hardness of 5 to 25 dKH. Using a reliable water testing kit will help you keep things in check. Perform the test regularly, though, to ensure the water quality remains high.

They also do well with some air stones and other methods of oxygenation, as they need heavily oxygenated water. With the powerheads and any under water jets, point them the length of the tank, rather than the depth. This will create a more natural “current” motion for them in the aquarium.

The biggest issue you’re probably have with Roseline sharks is providing them with enough swimming space. They require at least a 55-gallon tank, ideally they’ll live in 75+ gallons of water. They’re large (6-inches) in adulthood and do a lot of swimming. They definitely need as much swimming space as possible.

Creating the Landscape

Roseline sharks do best with normal lighting conditions created by LED lighting rigs. These can easily be tuned to adhere to your aquarium plants’ needs and maximize their growth while providing the Denison barbs with happy lighting as well.

The tank itself should be rectangular and long rather than deep, providing the fish with as much swimming space as possible. You’ll also need to cover the fish tank as these guys tend to be jumpers!

Provide them with fine gravel or coarse sand as their substrate, as this will most naturally reflect their natural environment. You should also choose decorations for inside the fish tank that will emulate their natural habitat. This means plenty of plants, rocks, smooth stones, pebbles and similar, but mostly leaving open spaces for swimming. They don’t like being bogged down with lots of décor.

They do enjoy hiding places, though, so an overturned flowerpot, some caves and overhangs, maybe treated driftwood or twisted “roots” to emulate their natural homes would be appreciated.

And note with the plants – dense planting is ideal (which is part of why you need such a large tank), but the plants need to be securely anchored, since the Denison barbs like to uproot the loose ones!

Doing all these things will give your fish a sense of solace and safety, reducing their stress and helping them live their best life possible.

Best Plants: Anubias, Java Fern, Hornwort, Pennywort, Vallisneria, Bacopa sp., Camomba, Amazon Sword, Pygmy Chain Sword, Dwarf Sagittaria
Best Lighting: Standard/medium
Best Decorations: Driftwood, pebbles, coarse sand or fine gravel substrate, rocks, river rocks, caves
Decorations to Avoid: Anything with sharp edges

Physiological Considerations for Roseline Sharks

Size: 6 inches
Lifespan:Up to 5 years
Temperament:Peaceful
Preferred Tank Region:Typically mid-level, but all levels potential
Scale Thickness: Nothing of note.
Gill Considerations: Nothing of note.
Swimbladder Considerations: Nothing of note.
Fin Shape Considerations:Nothing of note.

The Roseline shark is a colorful, vibrant, active species that thoroughly enjoys its wide-open swimming spaces and rewards you with flashy colors and fun personalities when they’re well cared for. The fish has a long, torpedo-shaped body with a silver color base. You might see some tinges of yellow or gold flecks throughout the body, under the right lighting conditions as well.

There’s a long, black stripe that runs the length of the fish’s body, from snout to the base of the caudal fin. Above this black stripe runs parallel a red stripe. This stripe doesn’t run the entire length of the body but fades mid-section. You’re also likely to see a bright red band on the front of the dorsal fin. The tailfin has black and yellow stripes that translates to both forked ends of the tail.

Mature males typically have bright green heads, as well, which helps set them apart from the female of the species. The size between the two, though, can also help with this identification. Females are typically slightly larger than males as well and tend to have duller coloration.

These fish tend to grow up to 6 inches long when fully mature. Their sizes helps to make their bright colors exceptionally visible and enjoyable in the fish tank.

Denison barbs often have a lifespan of up to 5 years, when well-cared for and kept in a properly maintained habitat. They need the proper diet as well (more below on what exactly this entails).

Roseline sharks are not the most delicate fish in the world, but they do require precise care for their lengthy lifespans to find fulfillment.

Society

Roseline sharks are a peaceful, extremely active and social fish that loves to school and splash about in good fun. They’re capable of a little aggression sometimes, though, it should be noted, if they don’t have enough room to establish their typical society (thus the large tanks required!).

The fish do not do well kept in isolation or even pairs – they truly need a decent-sized school to keep them healthy and stress-free. There should be at least six Denison barbs in every school, if not more.

Additionally, these fish do well with a variety of other species. They need to agile, fast swimmers who do well in the same type of environment and don’t have delicate trailing fins. Some great Roseline sharktankmates include:

Gender, Breeding, and Reproductive Considerations

Denison barbs are, unfortunately, rather hard to breed at home. It may happen by chance – some aquarists have reported this – but triggering their spawning process is nearly impossible for nonbreeders.

Commercial breeders must use hormones and elaborate setups to get these little guys to get together – and there are no known natural methods for helping the fish breed on their own.

Because of the difficulty, it’s best to leave this to the professionals and avoid disappointment and waste of resources.

Nutritional Needs

Denison Barbs are a natural omnivore that will happily eat any food it is given. In the wild, they will eat a wide range of foods that include insects, algae, and small invertebrates.

This fish needs to have a balanced diet. This will ensure the health and a longer life for your fish, but it also makes sure that their coloration is vivid.

The base of their diet should be a quality flake or pellet food. For your fish to have maximum color it is important to choose a dry food that also has carotenoids. If you do not buy high-quality food you will end up with food that is mostly padding. These cheaper foods lack nutritional value and the worst ones can cause long-term digestive health problems from the filler.

After deciding on a type of dry food, it helps to supplement it with both live and frozen food. This fish will happily eat things such as daphnia, brine shrimp, spirulina, and bloodworms. Another great option is blanched vegetables.

Denison Barbs should only be fed two times daily. They need only just enough food that they can eat within a two-minute window. If you feed more than this, you run the risk of making your fish sick by either overfeeding or by having the excess food spoil and start to affect the water quality.

Best Sustenance Food Type: A high-quality flake or pellet food is important to have for their diet.
Additional Food For Optimal Health:Choose live or frozen foods like blood worms, bring shrimp, and vegetables that have been blanched.
Special Foods and Considerations for Best Color and Growth:It is important to choose a dry food that is high in carotenoids, this will ensure the fish has better coloring.
When and How Often to Feed Fish Based on Life Cycle:You should only feed this fish twice a day, and only feed the fish what they can reasonably eat within a two-minute window.

Common Diseases and How to Avoid and Treat Them

Roseline Sharks are not known to suffer from any species-specific diseases, but they can experience all the common diseases that plague freshwater fish. They are fish that requires frequent maintenance on their tank water, so this is not a fish for those who aren’t willing to be vigilant.

Denison Barbs are known to be very sensitive to Ich. This is a disease that covers the fish in many painful tiny white spots. This disease is brought on by a mixture of poor living conditions in their tank and significant amounts of stress.

This fish needs to have pristine water conditions, their natural homes are mountains in India that have clear and clean water. Even the slightest build-up in the waste can start to trigger health problems. Allow waste to accumulate is asking for this fish to develop Ich. The tank needs to have a filter that is both quality and powerful.

Another needed step is to make sure to vacuum or otherwise remove any leftover food before it can start to rot. The gravel also needs to be routinely vacuumed to maintain water levels. The overall goal is to make sure the nitrate and ammonia levels remain so low that the fish will avoid becoming sick. It is important to not forget to also vacuum the tank corners, underneath any of the tank decorations, and around all of the plant stems. If you aren’t careful, then any leftover food, plant debris, and fish waste will pollute the water and sicken your fish.

In addition to all the care needed to remove wastes, the tank water itself will need to have at least 30-30% of its water changed out regularly.

Best Antibiotics: The best antibiotics to use are over counter broad-spectrum antibiotics.
Treatments to Avoid:There are no specific treatments to avoid.
Food Recommendations When Sick:Fresh food and avoiding anything that is heavily processed.
Hospital Tank or Isolation Withing the Community Tank:Place the sick fish in a hospital tank.

2 Facts About Roseline Sharks

  1. The Roseline Shark was first discovered back in 1895, but it wasn’t exported until nearly a century later. Because of this, they were listed as endangered for many years. Thanks to breeding, though, they’ve have some population growth.
  2. One of the reasons Roseline sharks make great community fish is that they have mouths too small to eat their tankmates who might be smaller than they! Even so, it’s important to provide them with some live food to keep them healthy and thriving.

Leave a Comment

Your email address will not be published. Required fields are marked *