Rainbow Shark Species Overview, Care & Breeding Guide

If you want a centerpiece fish in your freshwater aquarium that’s easy to care for, you must know about rainbow sharks.

This fin-buddy is pretty active and has an intriguing personality. It’s mesmerizing to watch it swim around the tank decor and plants.

If you are an avid fish enthusiast with a bit of experience, caring for this one can be a great treat!

In this piece, we will reveal the keys to their successful life in an aquarium. So, let’s dive in and uncover the enchantment it offers!

What is a Rainbow Shark?

OriginAsia: Mekong, Chao Phraya, and Xe Bangfai basins and Maeklong basin
Scientific NameEpalzeorhynchos frenatum
Common NamesWhitetail sharkminnow, Whitefin shark, Ruby shark, Red finned shark, Rainbow sharkminnow, Green fringelip labeo
IUCN Red List StatusLeast Concern
AppearanceElongated body, pointed snout, flat abdomen, raised dorsal fin
Greenish brown, deep black, dark blue, gray, or bright blue body color.
SizeUp to 10 cm (4 in) in captivity, 15 cm (6 in) in the wild
LifespanUsually, 4 years, but up to 6 years in captivity with the best care Up to 8 years in the wild
TemperamentAggressive and territorial, lively and active swimmers
Tank LevelBottom dwellers
Water Temperature75- 81°F (24-27 °C)
pH Level6-8
Water Hardness5-12 dGh
Care LevelIntermediate
Minimum Tank Size55 Gallons for one
Tank EnvironmentTank with plenty of plants, bogwood, driftwood, rocks, and caves to establish territory
DietPrimarily herbivorous, with slight carnivorous feeds
Tank MatesLarger and peaceful or semi-aggressive mid-level and top-dwelling schooling fish

What is the Natural Habitat of Rainbow Shark?

Rainbow shark thrives in the diverse aquatic landscapes of Southeast Asia, spanning the water basins stretching from China to Indonesia. Its natural habitat encompasses freshwater regions such as the Mekong, Chao Phraya, Xe Bangfai, and Maeklong basins.

The fish inhabits areas characterized by sandy substrates and are typically found at midwater and bottom depths within rivers and streams.

Notably, this fish exhibits a distinctive behavioral pattern. It migrates to flooded habitats during the rainy season, only to retreat to rivers as floodwaters recede.

According to the 2011 assessment of The IUCN Red List Status, the fish is labeled Least Concern.

Which family does Rainbow Shark belong?

The fish belongs to the family Cyprinidae within the order Cypriniformes. Its scientific name is Epalzeorhynchos frenatum.

Worldwide, it’s loved by various common names, such as whitetail shark minnow, whitefin shark, ruby shark, red finned shark, rainbow shark minnow, rainbow shark, green fringe-lip labeo, and redfin shark, adding to its colorful appeal.

Fun Fact: This species has been scientifically altered to naturally emit light, causing it to glow in the dark. This bioluminescence is the result of genetic modification, giving the fish a unique and mesmerizing appearance when viewed in low-light conditions.

How does Rainbow Shark look?

Albino rainbow shark
Albino Rainbow Shark

If you’re excited to discover further details about its physical attributes and behaviors, let’s plunge into the details!

What is the Size of a Rainbow Shark?

In its natural habitat, a mature fish usually reaches a length of approximately 15 cm (6 in). But in captivity, it averages around 10 cm (4 in). Both males and females exhibit similar sizes.

What is the Color of a Rainbow Shark?

The species is a captivating canvas of colors. Its body colors span a wide range, with captivating shades such as greenish brown, deep black, dark blue, gray, and bright blue.

The fins of this fish can range from radiant red to fiery orange, adorned with subtle yet dramatic dusky black accents. The tail is also red to orange in color.

It has a prominent black blotch located at the base of the caudal fin. The dorsal, anal, and pelvic fins take on a striking red coloration, accompanied by delicate dusky black accents that provide an elegant contrast.

A distinctive marking is observed along the linear path from the gill cover to the eye and mouth.

The fish also has a range of color variants. The naturally available ones are albino red-fin shark (white body and vibrant red/orange fins) and ghost sharkminnow (rarest variant: bluish sheen body, transparent white fins).

Another one is a man-made variant galactic purple rainbow shark, which emits a captivating fluorescent purple glow under ultraviolet light.

What are the features of a Rainbow Shark?

This species is easily recognized by its elongated body. Its snout is notably pointed, and the abdominal area appears flat, lending the fish a sleek profile.

It has a raised dorsal fin that gives it a shark-like appearance. Notably, it exhibits 11 branched dorsal rays, a forked tail, and gill rakers on the anterior side of the first arch.

What is the Sexual Dimorphism of Rainbow Shark?

Males exhibit distinctive characteristics, including notably thinner bodies, the presence of distinct black lines on their tail fins, and an overall brighter coloration compared to their female counterparts.

Female fish can be easily identified by their visibly rounder body shape in comparison to males.

What is the Behavior & Temperament of Rainbow Shark in the tank?

The red-finned shark is a bottom-dweller and active swimmer, frequently scouring the substrate for algae to consume. It is peaceful among its own kind in the wild, but aggression can arise when confined in a tank together.

Threat displays and fights may occur, involving head-and-tail butting and biting. Larger specimens might chase smaller ones until harm occurs or pursue other fish out of their territory, particularly in enclosed spaces like aquariums.

This behavior may heighten the risk of fish leaping out of the tank. Provide them with lots of space to swim around to minimize aggressive behavior.

What is the Lifespan of a Rainbow Shark?

In their natural habitat, the fish can survive for about 8 years. But when kept in tanks, it usually lives for 4 years and 6 years with excellent care.

Author’s Note: Introduce your rainbow shark as the final addition to your tank. In my experience, this approach can prevent the fish from attempting to dominate the entire tank and may contribute to minimizing territorial behavior.

How to take care of a Rainbow Shark?

Rainbow shark looking at the camera

If you’re excited about having this fascinating fish in your aquarium, let’s delve into important care guidelines to ensure its health and happiness!

What is the Tank Size of Rainbow Shark?

The fish needs lots of space to establish territories. So, consider a 55-gallon tank for one. You can keep a group of 5-6 in a 225 gallons tank.

What is the Water Chemistry of Rainbow Shark?

Now, let’s make sure that you provide the best water conditions to this fish to help it thrive and live for long years!

  • pH Levels: 6-8
  • Water Temperature: 75- 81°F (24-27 °C)
  • Water Hardness: 5-12 dGh
  • Ammonia: 0 ppm
  • Nitrite: 0 ppm
  • Nitrate: Below 20 ppm

What is the Tank Environment Rainbow Shark?

A good aquarium setup is also important for your pet fish’s joy. So, let’s work together to make the perfect home for them!

Which Substrate does Rainbow Shark need?

For the bottom of the tank, it’s best to use a fine and soft sandy substrate, as it mimics the fish’s natural habitat.

Gravel can also be used, but it should be smoothened and rounded to help prevent scratches and infections.

If you use gravel, regularly clean it as it collects waste.

Which Plants does Rainbow Shark need?

Plants assist rainbow sharks in establishing territories and further reducing aggression towards other fish. You can choose sturdy plants for their tank, like:

  • Anubias
  • Amazon sword
  • Hornwort
  • Java fern
  • Lemon bacopa, or bacopa
  • Vallisneria

Make sure to place the plants in the background so that you leave space for swimming in the middle.

Which Lighting does Rainbow Shark need?

For rainbow shark tanks, strong lighting is important to promote algae growth. Besides its daily diet, the fish constantly grazes on algae, so it’s essential.

LED aquarium lights are a practical choice due to their cost-effectiveness and programmability for natural day/night cycles. Lighting choices depend on the live plants you want, but a natural cycle is usually suitable for freshwater aquarium plants.

Which Décor does Rainbow Shark?

Include plenty of bogwood, driftwood, rocks, and caves. These will help the fish establish territories and break the line of sight, making the tank seem bigger.

What is the Filtration System for Rainbow Shark tank?

The fish is sensitive to waste buildup. To maintain its health, keep the aquarium water clean with a robust filter.

Opt for a hang-on-back filter (HOB) or canister filter. They are durable and ensure essential water movement and clarity.

What is the Water Flow Rate for Rainbow Shark?

The red-finned shark thrives with a fast flow rate simulating its native fast-flowing rivers. Aim for a flow rate around six times the tank’s volume, like 330 GPH for a 55-gallon tank.

A bubbler is highly recommended. It provides the high-oxygen environment they need.

Fish Care Tip: If you observe that your rainbow fin-buddy is more aggressive than usual, it might be that they are unwell.

What does Rainbow Shark eat?

The rainbow shark is primarily herbivorous but also has basic needs for carnivorous feeds. In its natural habitat, it has a diverse diet, including algae, insects, crustaceans, periphyton, phytoplankton, certain zooplankton, and decaying plant matter.

To replicate this in your tank, you would need to provide a mix of foods like:

  • Algae tablets
  • Insect larvae
  • Zooplankton
  • Brine shrimp
  • Bloodworms
  • Spinach
  • Peas
  • Lettuce
  • Celery
  • Carrot
  • Zucchini
  • Daphnia
  • Prepared fish food
  • Hikari algae wafers
  • Tubifex worms
  • Mosquito larvae
  • Live insects
  • Beet tops
  • Swiss chard
  • Shelled peas
  • Aquatic insects

The fish is not a picky eater but be cautious to not over feed it. Serve it three meals daily for about five minutes each time. Focus on providing a high-protein diet to enhance its vibrant color.

What are the Tank Mates for Rainbow Shark?

Rainbow shark’s aggressive behavior must be considered when choosing the right tank mates for it.

Top-level dwelling schooling species get along better with bottom-dwellers like this one. It is also better to choose peaceful or semi-aggressive, larger species that can defend themselves.

Here is the list of suitable tank mates for them:

If you intend to keep multiple rainbow sharks together, keep a group of at least five individuals.

Additionally, ensure that your tank provides at least one meter of territory per fish to minimize territorial conflicts and promote peaceful coexistence.

Which Tank Mates to Avoid for Rainbow Shark?

Avoid keeping them with the following fish types:

  • Other rainbow sharks: Can lead to aggressive territorial disputes. There can be dominance battles resulting in stress, injury, or even death.
  • Bottom-dwelling catfish: There can be clashes between preferred hiding spots and foraging areas.
  • Small or slow-swimming fish: May be perceived as potential prey or intruders and might become targets of aggression or harassment.
  • Fish with long fins: They may trigger the predatory instincts of rainbow sharks, leading to fin nipping or even damage to the other fish.
  • Similar-looking species (e.g., Red-Tailed Sharks): May be perceived as competition or threats leading to territorial aggression.
  • Betta fish: Can intimidate bettas, potentially leading to stress, fin nipping, or injury.
  • Goldfish: May lead to territorial disputes and may not be able to defend themselves against the aggression of rainbow sharks.
  • Guppies and neon tetras: Can lead to predation or stress.
  • Gouramis: Most gouramis can clash with the species leading to aggressive interactions.
  • Other cichlids: Can lead to competition for food and territory with most cichlids
  • Bala sharks: The size and activity level of bala sharks might stress these species and lead to aggression.

What are the Common Diseases in Rainbow Shark?

Though the fish is pretty hardy, it is still susceptible to quite a few diseases like the following:

Disease NameCausesSymptomsTreatment
Ich (Ichthyophthiriasis)Parasitic infection (Ichthyophthirius multifiliis)White spots resembling small pimples on body, fins, gills, and mouth; lethargy, loss of appetite; rubbing against objectsMedications to treat ich, improving water parameters
Swim Bladder IssuesOvereating, constipation, intestinal infectionsSwollen belly, abnormal swimming behavior (e.g., upside down, swimming in circles), difficulty maintaining balanceFeeding boiled peas to relieve constipation, addressing underlying causes; medication if needed
Fungal InfectionsPoor water quality, stressFungal growth on fish’s body, susceptibility to infections due to weakened immune systemTreatment: Antifungal medications, maintaining good water quality, antibiotics for bacterial infections
BloatOvereating, intestinal blockage, constipation, bacterial infectionSwollen stomach, difficulty swimming.Addressing underlying causes, antibiotics if the infection is present
StressSmall tank size, improper water parameters, overcrowding, inadequate tank maintenanceIncreased susceptibility to various diseases due to weakened immune systemProvide a sufficiently large tank, maintain proper water parameters (pH and temperature), regular tank cleaning, and water changes
Skin FlukesPoor water qualitySkin irritation, red spots, excessive mucus production, breathing difficulties if gills are affected Medication, raising water temperature, maintaining clean tank and proper diet
Fin rotBacterial infectionSluggishness, loss of appetite, fraying or disintegrating of fins, changes in fin colorImprove water quality, remove harmful objects, use antibiotics
ColumnarisBacterial infectionSluggishness, frayed fins, patches of gray/white, reduced appetiteEnhance water quality, antibiotics, reduce stress

Quick Tip: Ammonia produced by fish waste and leftover food can make your fish sick. Weekly, replace 20-25% of aquarium water and vacuum substrate to remove waste like fish excrement and uneaten food.

How to Breed Rainbow Shark in an Aquarium?

It’s pretty complex to breed rainbow sharks in a home aquarium due to their territorial aggression.

Establish a separate breeding tank to reduce stress and prevent potential harm to both adults and fry. Successful breeding involves several steps:

1. Breeding Tank Preparation & Management

Set up a spacious tank, preferably a minimum of 75 gallons, with sand substrate. Add a liquid dechlorinator to tap water to create a safe aquatic environment.

Incorporate rocks, decorations, and hiding spots within the tank to alleviate territorial behaviors and provide shelter for potential fry.

Install an adjustable heater and a reliable filter system to maintain consistent water temperature and quality.

Regular water changes, approximately 25% weekly, contribute to maintaining optimal water conditions.

Maintain the following water parameters at all times:

  • Water Temperature: 75-80 °F (24-27 75-80 °C)
  • pH Levels: 6.5-7

2. Introducing Breeding Pair

Select a mature male fish with intensified coloration, especially vibrant red hues along with their anal fins.

Choose a female fish that shows signs of abdominal swelling and behavioral changes as they prepare for egg deposition. This swelling is an indicator of egg development within the female’s body.

Make sure they are at least 4 inches in size, as this is when they sexually mature.

Introduce them into the breeding tank and observe their interactions closely for about a week. If aggression remains minimal after a week, let them be.

In case of the fair fighting each other or unsuccessful pairing, consider trying different pairs.

3. Mating Ritual & Signs of Pregnancy

The pair engages in unique mating behaviors, such as chasing, circling, increased interaction, and rubbing against each other.

To encourage it even further, provide a high-protein diet, such as brine shrimp or similar food options.

4. Egg Release & Hatching

The female fish deposits up to 1000 hard, transparent eggs onto the substrate. The male subsequently fertilizes these eggs with his milt.

Successful hatching relies on maintaining optimal water quality, as poor conditions or interactions with other tank inhabitants can threaten egg survival.

The eggs undergo an incubation period of approximately 2-3 days.

5. Setting Up Fry Tank

A separate fry tank is needed otherwise, the fry might get eaten by adult fish. Prepare a separate 10 gallons fry tank with dechlorinated water, a mini heater, and proper aeration.

An air stone connected to an air pump helps circulate the water and maintain suitable conditions for fry development.

6. Transferring Eggs & Fry Feeding

Carefully transfer the fertilized eggs to the fry tank using a gentle net. Upon hatching, the fry absorbs its yolk sacs for sustenance during the initial stages.

After the absorption of their yolk sacs, provide liquid fry food to the fry. Maintain this feeding routine for one to two weeks before transitioning them to baby brine shrimp.

7. Relocating Fish

Transfer the baby fish to individual tanks once they grow to a length of 1/2 to 1 inch.

Breeding Tip: The fish is usually bred using hormones. So, don’t be disheartened if you don’t succeed in breeding them.

How to Buy Rainbow Shark?

  • Look for rainbow sharks with clear and bright eyes devoid of cloudiness, growths, or discoloration. Healthy eyes indicate overall well-being.
  • Observe the fish’s body shape and movement. A healthy fish should show no signs of sluggishness or restricted movement, indicating its vitality.
  • Check the fish’s scales for cleanliness and ensure there are no dull or crusty areas, which may indicate a fungal infection. Examine its fins for tears or holes, even though they are common in this aggressive fish which is prone to fights.
  • When at the fish store, request to drop a bit of food into the tank and observe your chosen fish’s response. Watch how it interacts with other fish, as that will help you pick suitable tankmates later.

A word from FishInAquarium

The captivating rainbow shark in your tank can make your home aquarium mesmerizing with its dominating behaviors. The fish will always keep you entertained with its fighter spirit! With its hardy nature and your expertise, it’s also pretty fun to care for it.

If you found this information helpful, consider sharing it with fellow aquarium enthusiasts to spread the joy.

However, if you have any further questions or would like more information, please feel free to reach out via email. We’re here to help. Till then, happy fishkeeping!

Minnie B Miller - Professional aquarist and owner of FishInAquarium

About Minnie B Miller

Minnie B. Miller, a professional aquarist and owner of FishInAquarium, has over 8 years of expertise in fish breeding and care, gained through her roles at AquaticTX and Sea Lion Landing. Having honed her skills with various aquatic species, she is dedicated to empowering fellow enthusiasts by sharing her knowledge and experience.