Information, Cyprinids, Freshwater fish, Other cyprinids, Species

Rainbow Shark: Complete Species & Care Overview

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by Jason Matthews


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Rainbow Sharks are a unique and colorful fish species commonly found in the freshwater aquarium trade. These fish are a favorite among intermediate and experienced fish hobbyists due to their eye-catching coloration and active behavior. Despite their name, they are not actually sharks.

This article will explore the fascinating world of rainbow sharks, examining everything from their origin and physical characteristics to their behavior, living conditions in tanks, and diet.

You’ll discover something new about this fascinating species, whether a novice or a seasoned fish owner. Let’s dive in and see what the Rainbow Shark has to offer.


Scientific Name: Epalzeorhynchos frenatum
Common Names: Rainbow Shark, Rainbow Shark Minnow, Ruby shark, Whitefin Shark
Life Expectancy: 8-10 years
Adult Size: up to 6 inches (15 cm)


Origin Southeast Asia
Care LevelIntermediate
Temperament Semi-aggressive
Diet Omnivore
Tank LevelBottom
Tank Size30 gallons or more
Water pH6.0-7.5
Water Temperature75-82F (24-28C)
Water Hardness2-12 dKH
Tank MatesCompatible with similar-sized, peaceful fish. It can be kept with other semi-aggressive fish but should not be kept with other Rainbow Sharks or similar-looking fish such as Red Tail Sharks.

Fun Fact Corner

A fascinating fact about rainbow sharks is that they have special sensory cells in their fins called “lateral lines” that enable them to sense vibrations and variations in water pressure. They can navigate and find food in their natural environment thanks to the lateral lines’ ability to detect the movements of other fish and prey.

This is a crucial survival adaptation in their frequently hazy and dimly lit natural environment. Additionally, it explains why rainbow sharks are renowned for their lively and inquisitive behavior in aquariums.


Rainbow Sharks, scientifically known as Epalzeorhynchos frenatum, are a species of cyprinid fish that is native to the Mekong River Basin in Southeast Asia.

They frequently occur in Thailand, Laos, and Cambodia, where they live in floodplains and the lower reaches of rivers. The waters in these locations are renowned for being murky and slow-moving, making them the perfect habitat for Rainbow Sharks.

Appearance & Size

Rainbow Shark Appearance
Image: Valeronio, Depositphotos

The rainbow shark is recognized as a fish species with striking visual appeal for its vivid coloration and distinctive markings.

The body typically has a vibrant red or orange bottom and a dark brown to black top, creating a striking contrast. The fins are also a dark red or orange color. The vivid red or orange tail fin is the Rainbow Shark’s most distinctive characteristic.

The fish’s body is slim and elongated, and its dorsal fin spans its entire back. They have a pair of barbels on their mouths to locate food.

The Rainbow Shark has a maximum length of 6 inches in the wild, but it typically measures 4-5 inches in captivity.

They are regarded as medium-sized fish and can easily fit in a home aquarium of the right size.


It can be challenging to tell males from females. However, there are a few minute variations that can assist in distinguishing them.

The body shape of male Rainbow Sharks is typically longer, and their dorsal fin is more prominent. Additionally, their anal fins are longer and sharper.

Contrarily, female Rainbow Sharks typically have a rounder body shape and a less prominent dorsal fin. Additionally, their anal fins are shorter and more rounded.

It’s important to note that these differences can vary depending on the size and age of the fish and may not always be apparent.

Additionally, since male and female Rainbow Sharks have similar color patterns, coloration is not a reliable indicator of gender in this species.


In the aquarium, rainbow sharks are renowned for their active and energetic behavior. They have a reputation for frequently swimming around the tank, taking in their surroundings, and interacting with the other fish.

Additionally, they have a reputation for being extremely curious and may investigate any new items added to the tank.

Rainbow Sharks are semi-aggressive fish and may become territorial, especially regarding their own kind. It is possible to observe sharks establishing a hierarchy and defending their territory in a tank with several of them. Although some aggression and chasing may result, it usually doesn’t get too bad.

To avoid aggressive behavior, ensure they have plenty of hiding places and open swimming areas. Keeping them in a tank with non-aggressive fish species comparable to them in size and temperament is best.

It’s important to note that rainbow sharks are nocturnal fish, meaning they prefer to rest during the day and are more active at night. This behavior can be observed when keeping them in an aquarium.


These fish are semi-aggressive and may become territorial, especially regarding their own kind or similar-looking fish, such as Red tail sharks. Therefore you should avoid having more than one in a fish tank.

It’s crucial to select fish species comparable in size and temperament to Rainbow Sharks when choosing tank mates.

The Rainbow Shark tends to stay in the bottom of the tank, so choose tank mates that like to move around the middle or top.

Here are a few good tankmate options for Rainbow Sharks:

Additionally, it’s a good idea to do your research and make sure that the fish you choose for your tank are compatible with one another in terms of water quality and size. This will help to create a peaceful and healthy environment for all of the fish there.

Tank conditions

It’s crucial to give Rainbow Sharks a suitable tank environment when keeping them in captivity. To maintain the water quality, the tank must hold at least 55 gallons and have a good filtration system.

The water should be maintained at a pH of 6.5 to 7.5 and a temperature of 75 to 79°F (24 to 26°C).

Additionally, it’s critical to give them good aeration and a strong water flow.

The tank should be furnished with rocks, caves, and vegetation to provide the fish with hiding places and mimic their natural habitat. As active fish, it’s also crucial to give them a place to swim freely.

To maintain water quality and avoid toxin buildup, it’s crucial to keep the tank clean and perform routine water changes.

Rainbow sharks are territorial and can be slightly aggressive fish. To prevent any aggressive behavior and to accommodate their active behavior, it’s crucial to give them plenty of hiding places and open swimming spaces.


When it comes to the diet of Rainbow Sharks, it’s critical to give them a varied diet that includes both plant-based and protein options. Because these fish are omnivores, they consume meat and plant-based foods.

Some good options for protein-based food (can be fresh or frozen) include:

  • Bloodworms, brine shrimp, and daphnia
  • Pellets or flakes formulated for omnivorous fish
  • Small pieces of fish or shrimp

Some good options for plant-based food (can be fresh or frozen) include:

  • Vegetable-based pellets or flakes
  • Spinach, lettuce, and peas
  • Algae wafers

Instead of one large feeding, it’s a good idea to give Rainbow Sharks small meals several times throughout the day. By doing this, you can avoid overfeeding and maintain consistent water quality.

It’s also crucial to ensure the food you give them is suitable for their size and that they can easily consume it.


Because it requires particular conditions and a suitable tank setup, breeding Rainbow Sharks in captivity can be difficult. Because these fish are egg scatterers, fertilization occurs outside the fish’s body after they release their eggs into the water.

It is advised to keep a group of at least six individuals to increase the likelihood of having both males and females, increasing the likelihood of breeding. The tank needs to be densely planted and filled with hiding places for the fish to lay their eggs.

It’s crucial to give them the ideal water conditions, with a pH of 6.5 to 7.5 and a temperature of 75 to 79 degrees Fahrenheit (24 to 26 degrees Celsius).

When the females are prepared to reproduce, they will lay their eggs in secret, typically in a cave or vegetation. The eggs will hatch in two to three days, and the fry will begin to swim and hunt for food. The fry must be distinguished from the adults because they could become prey.

It’s important to remember that raising Rainbow Sharks in captivity requires a lot of perseverance, expertise, and experience. It is not advised for novice fish keepers.


It’s critical to be informed about the common diseases that can affect Rainbow Sharks and to take preventative measures to keep them healthy when it comes to their health.

The following diseases are most frequently found in Rainbow Sharks:

  • Ich: also referred to as white spot disease, is brought on by a parasite that attaches to the body and fins of the fish and causes the development of white spots.
  • Fin rot: a bacterial infection that results in ragged and frayed fins.
  • Swim bladder disorder: Poor water quality, a poor diet, or physical injury can all contribute to swim bladder disorder, which impairs a fish’s ability to move through the water.
  • Velvet: A parasite known as velvet causes the fish to grow a metallic-appearing layer of skin on their bodies.

To maintain water quality and prevent the buildup of toxins, it’s essential to keep the tank clean and to perform routine water changes; doing so will keep your fish healthy and stop them from becoming ill.

Futhermore, it’s extremely important to pay attention to the fish’s behavior and appearance and to seek veterinary assistance if you notice anything unusual.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

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