Roseline sharks are speedy fish with flashy colors. They are an excellent choice for large freshwater community tanks. Popular because of their colors, large schools of these fish can spruce up any tank.
These fish are sensitive to water quality. Yet, they can handle a wide range of pHs and water hardness. They are reasonably hardy, making them suitable for advanced beginners. Be prepared to test their water regularly.
For a more concise care guide, check out the table below.
What Are Roseline Sharks?
Roseline sharks are one of the larger fish available for freshwater tanks. They are colorful, fast fish that are pretty easy to care for.
These fish got the name “shark” for their silvery skin. They resemble sharks for their pointed dorsal fins and streamlined bodies.
Yet, they are not actually sharks and have peaceful personalities.
A thick black line runs down the length of their sides. A bright red line sits atop the black line and goes through the top half of their eyes. They have a bit of green on their heads, and their tails have black and yellow bars. The dorsal fin is transparent red and yellow.
They live in the highly oxygenated, fast-flowing rivers of southern India. Due to the over-exploitation of their species, they are on the endangered species list.
- Common Names: Roseline Shark, Denison Barb, Red Line Torpedo Barb, Roseline Torpedo Barb
- Scientific Name: Sahyadria denisonii
- Origin: Kerala & Karnataka, South India
- Length: 5 inches
- Aquarium Size: 55+ gallons
- Temperament: Peaceful; Schooling
- Ease of Care: Moderate
Roseline Shark Care, In A Nutshell
Consult this roseline shark care sheet for quick care tips:
| Aquarium Size | 55+ gallons |
| Water Temperature | 72-76°F (22.2-24.4°C) |
| pH | 6.8-7.8 |
| General Hardness (GH) | 5-25 |
| Safe Water Levels | Ammonia: 0 ppm Nitrites: 0 ppm Nitrates: <10 ppm |
| Water Flow | Lots of flow Lots of oxygen |
| Substrate | Sand or gravel |
| Decorations | Lots of vegetation Driftwood Caves |
| Tank Mates | 6+ roseline sharksFast, peaceful fish of similar sizes Snails & large shrimp |
| Diet | Omnivores — meaty & plant-based diet |
| Common Health Issues | Ich |
How To Care For Roseline Sharks
Roseline sharks are fairly easy to care for. They are suitable for intermediate to advanced-beginners. Roselines are sensitive to ammonia, nitrites, and nitrates — test the water regularly.
Tank Size
Roseline sharks grow larger than many tropical water fish available in pet stores. They can grow up to four to five inches and need a large aquarium to match.
Roseline sharks are dither fish — a group that swims near the top of the tank. They have high energy levels and are constantly swimming about. Aquarists must provide them with plenty of space to travel and explore.
Roseline sharks are a schooling species. Aquarists must have groups of at least six sharks.
In the wild, roselines may form schools of over 100 fish. The more fish in a school, the safer they feel.
Minimum Tank Size
The smallest acceptable tank for a school of six roseline sharks is 55 gallons. The larger the school an aquarist plans to keep, the larger the tank they’ll need.
Besides being continuously active, roseline sharks are fast swimmers. A tank that is longer than it is tall is the best option for this species. Aquariums should be at least 4 ft (1.2 m) long.
It’s always best to provide fish with an aquarium larger than the smallest one required. Extra space keeps fish happy, reduces aggression, and keeps the tank cleaner.
More Room For More Fish
Aquarists need six to ten gallons for each extra shark.
Tanks that are too small will cause the fish to suffer. Roseline sharks experience stress when they are too crowded. Stressed fish often rub their noses against the glass. The rubbing can cause sores, which can lead to infection.
Too-small tanks may cause them to startle more easily, too. Keepers have observed their roselines darting right into the side of their aquarium.
Keep The Tank Covered
Placing a secure lid or hood over the aquarium is essential. Due to their fast nature, roseline sharks are good jumpers. Full-grown roselines can jump with enough force to lift standard lids and may end up on the floor.
Lids should always be secure to avoid the fish getting out of their tank.
Water Parameters
In the wild, roseline sharks live in clean, highly-oxygenated water. Aquarists must provide their fish with excellent water conditions for them to thrive.
For best results, keep the aquarium within these parameter ranges:
- pH: 6.8-7.8
- GH: 5-25
- Ammonia: 0 ppm
- Nitrites: 0 ppm
- Nitrates: >10 ppm
Ammonia, Nitrites, & Nitrates
Roselines are sensitive to poor water quality. There should never be any ammonia or nitrites in the tank.
Keep the nitrate levels as low as possible, below 10 ppm. Roselines become stressed when the nitrates rise above 10 ppm, and their colors fade.
Hobbyists should never place roseline sharks in an unstable aquarium. Hardier species should go into the tank first in case of any fluctuations. Once the water is stable and the water parameters low, then aquarists can add the roseline sharks.
NEVER add roseline sharks to an uncycled tank.
Some fish, like zebra danios, do okay in an uncycled tank. Some aquarists even use these hardier species for a “fish-in” cycle.
A fish-in cycle refers to using fish to help the nitrogen cycle go faster than in an empty tank.
Due to their sensitivity, roseline sharks are not a good species to attempt a fish-in cycle.
pH & Water Hardness
Despite their sensitivity to waste, they are tolerant of other water conditions.
They can handle wide ranges in pH, hardness, and temperature. They prefer neutral pH but can handle more acidic or basic water. The water hardness doesn’t seem to affect them at all.
Considering their hardiness, keeping these fish happy is not exceptionally difficult. They are suitable for intermediate keepers or advanced beginners.
Filters
It’s best to opt for larger filters to maintain pristine conditions.
For instance, most aquarists who own a 55-gallon tank would buy a filter rated for a 55-gallon tank. Yet, those raising roseline sharks should buy a filter rated for a 75, or even 100-gallon aquarium.
Using a larger filter ensures the filter can keep up, even if the fish create a lot of waste. Larger filters easily keep the aquarium clean. Still, hobbyists must keep up with water changes and avoid overfeeding.
Water Flow
Don’t be afraid to choose a filter with some power — roseline sharks like fast-moving water. Providing them with a decent amount of current helps them get more exercise.
Ensure there are also areas in the tank without flow to give them a space to rest when needed.
Powerheads are good additions to the tank for flow.
Angle powerheads in a way that provides a constant current for the fish to swim through.
Usually, it’s best to angle powerheads horizontally across the water’s surface. Doing so creates current across the top of the tank while leaving a slow-moving area for rest at the bottom. Positioning the power head at the water’s surface also produces more oxygen.
Oxygen
Roseline sharks need plenty of oxygen. Filters, bubblers, and powerheads are all excellent for aerating the water.
Creating more movement on the surface of the water encourages gas exchange. The more movement the water has, the more oxygen goes into the water.
These sharks live in cooler waters, which are rich in oxygen. Ensuring their water doesn’t get too warm helps keep their oxygen levels up.
Temperatures
Roseline sharks are tropical fish. Yet, they prefer slightly cooler waters than other tropical species. Those who live in warm climates year-round may not need a heater in the tank.
Aquarists should never keep these fish above 80°F (26.7°C) — their bodies can’t handle it.
Instead, the temperature should stay between 72-76°F (22.2-24.4°C).
We encourage all roseline owners to have heaters even if they live in a warm climate.
The benefit of heaters is that they keep the water temperature stable. Temperatures in tanks without heaters will fluctuate as the surrounding air changes. Heaters prevent temperature fluctuations that may make roseline sharks sick.
Be sure to buy an adjustable heater. Adjustable heaters are safer than non-adjustable heaters. It’s also beneficial to be able to adjust the temperature if fish get sick.
Keep a thermometer in the tank and check the temperature every day. It’s rare, but heaters can malfunction, which can be fatal to fish.
Substrate
Roseline sharks spend most of their time in the middle of the tank and aren’t picky about the substrate. Gravel or sand will both work equally well for these fish.
Aquarists should choose the substrate that works best for their bottom-dwelling critters.
Substrates made for plants are always an excellent option. Plant substrates contain beneficial nutrients and encourage plant growth.
Decorations
Caves and driftwood offer good hiding spots for timid roseline sharks.
Bear in mind that untreated driftwood releases tannins that turn the water a light brown. The tannins contain nutrients that are good for the fish.
Those that don’t want tannins can boil the wood before adding it to the tank. Boiling it for a few hours removes the tannins.
Driftwood lowers the pH slightly, which shouldn’t be an issue for roseline sharks. Test the water regularly to ensure the pH doesn’t get too low.
Vegetation
Roseline sharks enjoy having lots of vegetation to swim around in. Keep the plants to the side and back of the tank, creating thick bush-like shelters.
Keep the middle of the tank more open for easier swimming. Fish feel more comfortable swimming in the open waters when they know there is shelter close by.
It’s best to choose tall background plants and short carpeting plants. Floating plants create shade and make these fish feel more comfortable.
Secure the plants to the substrate with root tabs to prevent the fish from uprooting them. They rarely try to eat the plants. Still, their swimming habits often uproot plants.
Here are some excellent medium to tall background plants:
- Vallisneria (Vallisneria spiralis)
- Amazon swords (Echinodorus sp.)
- Anubias sp.
- Bacopa sp.
- Cabomba sp.
- Hornwort (Ceratophyllum demersum)
- Java fern (Leptochilus pteropus)
- Pennywort (Umbilicus rupestris)
Here are some good, short, carpeting plants:
- Pygmy chain swords (Echinodorus tenellus)
- Dwarf sagittaria (Sagittaria subulata)
Great floating plants include:
- Red root floaters (Phyllanthus fluitansor)
- Water lettuce (Pistia stratiotes)
What About Fake Plants?
Live plants are the best option because they provide oxygen and help purify the water. Still, live plants can be tricky and aren’t the best option for everyone. Those wishing to avoid live plants can find many great silk plants.
Avoid hard plastic plants. Their edges are sharp and can cut the bodies and fins of fish.
Cleaning
Keeping on top of cleaning is essential to keep the water pristine.
Perform a 15 to 30% water change once a week. Use a gravel vacuum to get all the waste from between the substrate.
Test the water at least once weekly to ensure the ammonia, nitrites, and nitrates stay low.
Tank Mates
Roseline sharks are generally peaceful schooling fish. They enjoy being in the company of other fish. The more fish they have around, the safer they feel.
Other Roseline Sharks
Roseline sharks must live in schools of at least six fish — having 12 or more is ideal. Keeping a single roseline shark in a tank will cause the fish to become aggressive. The more roselines live together, the more peaceful they tend to be.
Having large (12+) schools of roseline sharks is more appealing for aquarists, too. The schooling behavior shows off their shimmering colors. The colors don’t stand out as well when there are fewer fish in the tank.
Bad Behavior
Keeping these fish in schools reduces bad behavior, though it doesn’t completely get rid of it.
Roselines may nip at fins at times; avoid housing them with fish that have long, flowy fins. Bettas and guppies, for instance, don’t make good tank mates for roseline sharks.
They may occasionally nip at members of the same species, though this is rare. Usually, it is the males that will go after each other. They seem to make more of a show of their “aggression” and never really hurt each other.
Roseline sharks have small mouths. They cannot eat small fish or most pet invertebrates.
They do eat brine and mysis shrimp; they might try to go after pet shrimp in the tank. Keepers should only choose larger shrimp.
Roselines are more likely to show aggression if their tank is too crowded. As they do best in large schools, having a large tank is necessary to accommodate them. A crowded tank causes stress, and the excess waste will cause a spike in ammonia.
Avoid Small & Slow Fish
Despite being primarily peaceful, roseline sharks shouldn’t live with small fish. Their large size and speedy swimming frighten smaller fish. Roselines may accidentally bump into smaller fish and cause injuries as well.
They shouldn’t live with slow fish, either. Slower fish can’t compete with roseline sharks for food and may be targets of nipping.
Small and/or slow fish and inverts that shouldn’t live with roseline sharks include:
- Small tetras (e.g., neons or embers)
- Rasboras
- Guppies
- Fancy goldfish
- Bettas
- Small shrimp (e.g., cherry shrimp)
Ideal Tank Mates
Medium-sized fish that do well with roseline sharks include:
- Gouramis
- Barbs
- Peaceful to semi-aggressive cichlids
- Rams
- Angelfish
- Apistogrammas
- Golden dwarf cichlid
- Kribensis
- Larger tetras (e.g., black skirt or serpae tetras)
- Corydoras catfish
- Plecos
- Giant Danios
- Swordtails
- Mollies
- Rainbowfish
- Yoyo loaches
- Zebra loaches
Invertebrates that do okay with roseline sharks include:
- Snails
- Large shrimp
- Bamboo shrimp
- Vampire shrimp
- Amano shrimp
Feeding
Roseline sharks are omnivores that are not picky about what they eat. Feed them plant and meat-based foods to keep their metabolism healthy. Providing them with a good balance of these foods also helps their colors to pop.
Healthy live or frozen meaty foods:
- Daphnia
- Bloodworms
- Blackworms
- Glass worms
- Tubifex worms
- White worms
- Brine shrimp
- Mysis shrimp
Healthy plant-based foods include:
- Algae wafers
- Spirulina (blue-green algae)
- Phytoplankton
* These foods are often available in flakes and pellets — check the ingredients lists. *
Flakes & Pellets
These fish aren’t opposed to flakes or pellets. Aquarists should ensure they choose pellets or flakes made for tropical fish.
Flakes and pellets should be high in protein. Meat-based proteins should be the first ingredient in any pellets or flakes. Fluval Bug Bites is one of the best brands available.
Pick pellets that sink since roseline sharks are not surface feeders. Hobbyists can get flakes to sink by submerging them in the tank water. Do this rather than sprinkling them on the surface.
To help their colors pop, choose flakes or pellets that contain carotenoids. Carotenoids are orange, red, and yellow pigments that occur naturally in plants. They help the roselines’ colors to pop.
Breeding
Breeding roseline sharks can be tricky. It took professional breeders years to get their fish to spawn.
Roseline sharks are endangered because of the exploitation for the pet trade. Despite their dwindling populations, the demand for roselines continued to go up. Sellers looked for solutions to continue supplying hobbyists with these colorful fish.
Breeding facilities were set up across India and Southeast Asia. These breeding facilities experimented with hormonal treatments. Eventually, the breeding program was a success.
Breeders use a combination of hormone injections and outdoor ponds for reproduction. Hundreds of gallons of space and dozens of fish are necessary to encourage breeding. Such methods are not workable for the average aquarium keeper.
Today, most roseline sharks available in pet stores are captive-bred.
Health Problems — Ich
Roseline sharks are a hardy species that rarely become ill. Still, they are more susceptible to ich than many other species.
It’s easy to tell when something is wrong with roseline sharks because their color fades. Their color often fades when the water quality is off, causing them stress.
Hobbyists must check their water conditions regularly. Waiting until their colors change may not be soon enough. Poor water conditions cause their immune systems to drop and make them more likely to get sick.
What Is Ich?
“Ich” is short for Ichthyophthirius multifiliis, a type of protozoan parasite. Ich can devastate aquariums because it spreads rapidly and can kill every fish. A single spot of ich can spread like wildfire and infect every individual.
What Does Ich Look Like?
The telltale sign of ich is uniform white spots anywhere on the body. They look like grains of salt.
Don’t confuse ich with fungal infections. Fungus is not consistent in appearance and is usually fuzzy.
By the time ich is visible, the fish is already very ill. It’s better for aquarists to catch the infection before the white spots appear.
Early signs of ich include:
- Irritation
- Excess mucus production
- Flashing
- Loss of appetite
- Decreased activity
- Weakness
How To Treat Ich
Treat ich right away before it spreads to the whole tank.
A single treatment is not enough because the parasite has several life stages. Ich treatment is only effective during part of the parasite’s life.
As they are microscopic, it’s impossible for hobbyists to tell which life stage the parasite is in. They must treat the tank for several weeks to ensure they’re attacking the parasite at the right time.
Chemical treatments are the most effective:
- Copper sulfate (Most effective — best for ponds)
- Formalin (Most effective — best for tank systems)
- Ich-X (Safe for scaleless fish, inverts, and plants)
- Medications with formaldehyde
- Malachite green
* Never use copper sulfate if there are inverts or loaches in the tank. These organisms are extremely sensitive, and copper is toxic to them. *
* Avoid potassium permanganate as it can damage the skin, gills, and eyes. It is a good treatment for most external parasites, but not ich. *
Adding aquarium salt to the tank can help speed up healing as it’s good for the skin. Read the directions carefully, as adding too much salt can be fatal.
* Aquarium salt will kill most invertebrates and is likely to kill plants. *
Causes Of Ich & How To Prevent It
Besides stress, new fish, plants, and rocks can introduce ich to a tank.
Aquarists must quarantine all new animals and items for at least two weeks. The quarantine period gives the aquarist time to spot illness and treat it. Organisms can go into the main tank after the quarantine period.
Never share equipment between tanks without properly disinfecting them.
FAQs
Is It Possible To Breed Roseline Sharks In A Home Aquarium?
It is nearly impossible to breed roseline sharks in the home aquarium. Hobbyists simply don’t have the space necessary.
In a few cases, hobbyists have accidentally bred roseline sharks. In all these cases, the aquarists had at least 15 roseline sharks. Plus, the hobbyists weren’t trying to breed their fish.
There are no known cases of home aquarists successfully breeding roseline sharks intentionally.
Plus, little is known about caring for roseline shark fry. The parents are also likely to eat the fry if they are not separated.
How Often Should You Feed Roseline Sharks?
Since roseline sharks are very active, they should eat twice a day. Avoid feeding them at sunset or sunrise — this is when they get most temperamental.
How Much Do Roseline Sharks Cost?
An individual roseline shark typically costs between $9 and $20. They are more expensive since they are endangered and difficult to breed.
How much these fish cost depends on their size and how many fish a hobbyist buys. Buying roseline sharks in bulk will usually save the buyer money.
