Freshwater Fish

Rainbow Shark – Epalzeorhynchos Frenatum: Care Guide

If you’re looking for a colorful and active fish to add to your tank, the ever-popular freshwater rainbow shark (Epalzeorhynchos frenatum) might fit the bill. Unfortunately, rainbow sharks are often not kept in large enough aquariums and with the right tank mates. So what do these beautiful fish need to be happy and thrive?

Read our care guide to find out everything you need to know about rainbow shark care.


Scientific name: Epalzeorhynchos frenatum
Common name (species) Rainbow shark, rainbow minnow shark, ruby ​​shark, redtip shark, green fringelip labeo, whitetip shark, redtip shark, and whitetail minnow shark
Family Cyprinids
Source Indochina, specifically Mekong, Chao Phraya, Xe Bangai, and Maeklong
Diet Omnivore
level of care Intermediate
Exercise Active bottom-dwelling fish
Life expectancy 5 to 8 years
Temper semi-aggressive
tank level bottom dweller
Minimum tank size 50 gallons
Temperature range Tropical 75° to 81° Fahrenheit
Hardness of water 5 – 11 dGH
pH range 6.5 to 7.5
Filtration / Flow Rate Prefers clean well-oxygenated water and a moderate flow
type of water Sweet water
Breeding Egg layer, extremely difficult to breed in captivity
Compatibility Moderate. It gets along well with many other species of freshwater fish.
OK, for planted tanks? insurance with plants


The rainbow shark (Epalzeorhynchos frenatum) is found in the Mekong, Chao Phraya, Maeklong and Bangfai basins in Indochina.

The rainbow shark is listed on the IUCN Red List as being of least concern, although its numbers in the wild are declining largely due to habitat destruction.


In the wild, the rainbow shark lives in bodies of water where the substrate is sandy, frequenting the bottom of the river where the fish feed on plankton and algae. The fish migrate to flooded areas in the rainy season and return to the rivers when the flood dries up.


Rainbow sharks are extremely attractive fish, a dark slate gray color with bright red-orange fins.

The fish are long and flat-bellied with a pointed snout and an upright dorsal fin that gives the fish a shark-like appearance. As young, both sexes are quite indistinguishable. Once the fish reach sexual maturity at around four inches in length, the females have a thick body, while the males are slimmer with fine black lines on the tail fin and are usually brighter in color.

There is also an albino variant of the Rainbow Shark. The albino rainbow shark has the same bright red-orange fins as its cousin, but its body is white.


Rainbow sharks and albino rainbow sharks generally grow to be around 6 inches long when fully mature.


Rainbow sharks live five to eight years in captivity when provided with a high-quality diet and well-maintained conditions.


These fish live on the bottom, but are also active swimmers, busily scurrying across the substrate in search of algae to eat. For that reason, it is important that the tank you choose is rectangular to provide ample swimming space for your Rainbow Shark.

Although rainbow sharks are not known as jumpers, escape attempts are sometimes made when the fish are first introduced to a new tank. Therefore, to be on the safe side, your aquarium should have a slip-on lid or a tight-fitting lid.


Rainbow sharks are a territorial species, and that can result in some degree of belligerence and intolerance towards other fish that encroach on the shark’s space. Although juveniles are generally shy and peaceful creatures that tend to hide from others, they generally become more aggressive as the fish mature.

However, despite the Rainbow Shark’s antisocial reputation, you can include community fish in your tank, as long as the species you choose like to hang out in the upper areas of the water column. Other bottom dwellers should be avoided, as your shark will almost certainly chase and intimidate the intruder, biting and generally intimidating the unlucky fish.

That behavior can be controlled to some extent by providing plenty of caves, overhangs, and other suitable hiding places. It is also essential for peace and harmony in your aquarium that you do not overdo it in the tank.


Peaceful species that are generally benign but still capable of defending themselves are a good choice as tank mates for red sharks. Good examples are barbs, danios, rainbow fish, and gouramis.

It’s also a very good idea to make your rainbow shark the last fish you introduce to your tank. That will prevent the fish from trying to claim the entire tank and should help reduce territorial behavior.


It is generally not recommended to keep rainbow sharks in groups. These fish are not a schooling species and tend to be intolerant of their own kind, being solitary territorial creatures in their natural environment.

There simply isn’t enough room for more than one rainbow shark in a normal sized aquarium, and the larger specimens will chase and harass the smaller, weaker ones, often with a fatal outcome. If you really want to have more than one rainbow shark, you should have a group of at least five, and your tank should allow at least one meter of territory per fish.


In addition to avoiding other bottom-dwelling fish species that might be viewed by the rainbow shark as competitors for territory, I recommend that you do not keep other freshwater sharks , catfish, and certain species of cichlids in the same tank as a rainbow shark. rainbow shark. .


As with any species of fish, an essential part of keeping your aquarium is providing your fish with a high quality, nutritionally balanced diet in the correct amount.


Rainbow sharks are omnivores and require a diet that includes meaty protein and plant matter.

The fish eat algae, zooplankton, insect larvae, and decaying plants in their natural river environment.

Captive rainbow sharks will happily eat most food that reaches the bottom of the aquarium. That includes tropical flakes, pellets, frozen foods, live foods, greens, and seaweed. To ensure that the colors of the fish remain vibrant and bright and that the juveniles grow properly, you should offer your fish a good variety of live and frozen meaty foods, such as bloodworms, brine shrimp, and daphnia.


As with most species of fish, it’s best to feed your rainbow shark small amounts of food two to three times a day.

Offer the fish what it will consume in a few minutes. Be careful not to overfeed, as uneaten food will break down in the tank, causing water quality issues and increasing the bioload on your biofilter.



As mentioned above, rainbow sharks are active fish that need plenty of room to swim and are also territorial. For that reason, you need a tank that is at least 50 gallons, and a rectangular aquarium is the best option.

Although I do not recommend keeping more than one rainbow shark, if you intend to keep a group of these fish, you will need a 125-gallon aquarium that is at least six feet long.

As mentioned above, make sure you choose a tank with a sliding lid or a tight-fitting lid so your fish can’t jump out.



Sand is the most suitable substrate for rainbow sharks and reproduces the river bottom of their natural habitat. That said, you can use gravel if you prefer, but choose a very soft or fine gauge variety that doesn’t have any sharp pieces that can hurt your fish.


>As rainbow sharks are very territorial, it is important to provide them with plenty of caves, driftwood, twisted roots, and rocky outcroppings that the fish can claim as their own.

Dense planting works well, as clumps of bushy growth can provide a distraction and also act as territorial markers.



Rainbow sharks live in rivers where the current is quite fast and the water is well oxygenated. So a fast flow into your tank will replicate that environment perfectly, as well as help improve the performance of your filtration system.

An external canister filter or box filter augmented by a powerhead might be the best arrangement for maximum flow and super efficient filtration and oxygenation.

When choosing a filter, keep in mind that you need a suitable unit with a GPH rating. GPH stands for gallons per hour and it tells you how many times the total volume of water in your tank circulates through the unit during a one hour period.

The recommended minimum GPH is four times the volume of your aquarium. So, if you have a 100-gallon tank, the minimum GPH you want is 400. Keep in mind that the GPH rating is often based on empty or low-stock tanks. Therefore, it is best to choose a slightly higher GPH to get the most efficient filtration for your tank.


Tropical fish need specific water parameters to stay healthy and thrive. So make sure you set up your aquarium according to the needs of your fish and check the water conditions regularly.

water temperature

Rainbow sharks are tropical fish that need a water temperature of 75° to 81°F.

pH range and water hardness

Your aquarium water should have a pH between 6.5 and 7.5 with a water hardness of 5 to 11 dKH.


Rainbow sharks do not need any special lighting. LED lighting units are generally cheaper to operate, and programmable systems are available that allow you to set day or night cycles to suit your fish and plants.


Like most species of fish, rainbow sharks need clean, well-oxygenated water to stay healthy.

To keep your aquarium spotless and help your filtration system, deep clean the substrate weekly with an aquarium vacuum to remove fish debris, uneaten food, and general debris. Vacuum around the base of plants, under box filters and trim, and in the corners of the tank where debris tends to collect.

At the same time, perform a 30% water change. Periodically rinse the filter media and sponges in a little tank water to remove sludge and replace filter cartridges as needed per manufacturer’s guidelines.


When setting up your aquarium, start by gathering everything you need, including:

  • Sand or fine gravel substrate
  • LED lighting unit
  • canister filtration system
  • Heater
  • aquarium thermometer
  • Decorations, including driftwood, rocks, and caves.
  • Floors


  1. Rinse the substrate thoroughly under running water to remove residual dust and dirt.
  2. Place two to three inches of the substrate on the floor of your aquarium.
  3. Place the heater and filter unit in the tank, but do not turn them on yet.
  4. Fill the tank with tap water that has been treated with a water conditioner to remove chlorine and chloramine. Pour the water in the tank over an upturned container to avoid spreading the substrate throughout the aquarium.
  1. The water must contain ammonia to start the nitrogen cycle in the biological filter media, so add a pinch of fish food, some substrate from a mature tank, or a few drops of pure ammonia to the water.
  2. Wash the decorations to remove dust and place them in the aquarium.
  3. Cut off dead or brown plant leaves and remove dead stems. When planting, leave enough space between your plants so they have room to grow and spread.
  4. Turn on your filtration system and heater. If you have live plants, you will need to have your tank lights on for eight to ten hours each day so the plants can photosynthesize.
  5. Now, you need to wait ten days before introducing any fish so the tank can fully cycle. Test the water to ensure ammonia and nitrite levels are at zero and nitrates at a maximum of 20 ppm. If necessary, wait a few more days before adding fish to the setup.


Rainbow sharks are fairly hardy fish that are in good health, provided they are offered a nutritious diet, the correct water parameters, and are kept in a well-maintained aquarium.


Rainbow sharks are typically active fish that spend a lot of time grazing algae on the substrate.

You want to see your fish busy and feisty, taking out any tankmates that have strayed too far into the Shark’s territory.


There are some red flags to watch out for, including:

  • loss of appetite
  • Inactivity
  • Swellings, ulcers and patches of reddened skin.
  • Rubbing body against aquarium decorations or hitting substrate


Health problem Symptoms or causes suggested action
Ich (white spot disease) White spot disease is probably the most common disease of aquarium fish and is also known as Ich. White spot is caused by a ciliated protozoan parasite called Ichthyophthirius multifiliis. Symptoms include knocking against substrate and tank ornaments. After a few days, a rash of small white spots appears all over the fish. Raise the water temperature to 82o F for a few days and treat the water with an Ich treatment.
skin and gill flukes Flukes are parasites that attack the body and gills of fish. Fluke fish rub against substrate tank decorations, as well as secrete excessive mucus. Treat the aquarium with an antiparasitic drug.
fungal infections White fluffy growths. Quarantine all affected fish and treat the water with an antifungal treatment.
Bacterial infections Red spots on the skin, sores, ulcers. Quarantine affected fish; Treat the aquarium with antibacterial drugs.


Rainbow sharks reach sexual maturity once they are over four inches long.

In the wild, spawning usually occurs seasonally from October to November. That said, the exact breeding month varies depending on the amount of daylight and the temperature of the water. Rainbow sharks are egg layers. The female lays her eggs, which are then fertilized by the male. The eggs usually hatch within a week.

Most of the rainbow sharks found for sale in fish stores and online are commercially raised on fish farming farms in Southeast Asia. The species is virtually impossible to breed in the home aquarium, largely due to the aggressive territorial nature of the fish within a confined environment.


Rainbow sharks are often available at good fish stores and through online dealers and fish stores for only a few dollars per fish.


  • a grid
  • algae magnet
  • aquarium thermometer
  • aquarium vacuum cleaner
  • Books on tropical fish farming
  • Filtration system
  • Fish tank (minimum size 50 gallons)
  • Heater
  • High quality tropical fish flakes
  • LED lighting unit
  • Floors
  • Rockwork, driftwood, twisted roots, caves
  • Sand or fine gravel substrate
  • Frozen food selection
  • water conditioner


I hope you enjoyed our article on caring for the beautiful and feisty Rainbow Shark.

Do you have a rainbow shark? Which tankmates work best with your shark? Tell us in the comment box below!

And remember to share our guide with your friends if you liked it!

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