Rainbow Shark – 5cm

Rainbow Sharks, also known as Red Fin Sharks or Ruby Sharks, are small tropical freshwater fish native to Thailand.  They are known for their vibrant red fins and being territorial and dominate. This generally happens as they mature. As juveniles they are timid and will spend large periods of their time hiding.  They are active swimmers and tend to spend most of their time dwelling at the bottom of the tank. Due to them being bottom-dwellers, they are known as aquarium cleaners as they will eat the algae growing on the bottom of the tank.  You should make sure your aquarium is long and has plenty of space for your Rainbow Shark to swim on the same level.

Despite what its name would imply, their upright dorsal fin which gives them the appearance of a shark, it’s a type of carp and belongs to the Cyprinidae family.

Behavior

Due to its territorial nature they should be kept in large aquariums. It is an omnivore and not a fussy eater, eating most things placed into the aquarium.  As juveniles you will find your Red Tails to be fairly timid. For this reason you should provide them with plenty of spaces to hide.  As they mature into adults they will become territorial and can be aggressive to fish which stray into their territory. While they won’t physically bite or harass other fish they will chase them to the point of exhaustion.

Day to day you will find this fish swimming back and to in the bottom section of the tank. During feeding time you will notice them bullying other fish if you feed them too closely together.  It is a very active fish that will spend the majority of its time busy in your thank.

Tank Conditions

As they are known for being territorial ensure that juveniles have a tank sized at least 100 litres and adults should be placed in at least 200+ litres.  You should also try to split the tank up to limit the amount of territorial behavior and help protect more timid tank mates. Due to the Rainbow Shark’s territorial nature, you should ensure your aquarium has lots of hiding places for them. Think caves, treated driftwood and rocks.

For the water flow you should try to make sure the water is fast flowing to replicate their natural environment. For substrate, they are best suited to sand, as this is what is found in their native Thai rivers. Be careful if you intend to use gravel because the sharp edges can cut them. If you do decide to use gravel make sure it’s very fine.

With Rainbow Sharks you need to keep the pH level stable. Sudden changes in the pH level can cause them to become more aggressive than usual.  Lighting should be kept at a medium level, and the water movement should be moderate.

WARNING: they’re no known for jumping but it isn’t unheard of, so an aquarium lid should be used. Jumping generally occurs when they are first placed in the aquarium.

Compatibility

As a general rule they aren’t aggressive towards species that don’t look like Rainbow Sharks. As the Rainbow Shark dwells at the bottom of the aquarium, avoid other bottom-dwelling fish such as cichlids and catfish. You should also avoid any similar looking fish, i.e. Red Tail Sharks and Bala Sharks. If you make sure the Rainbow Shark is the last fish placed in your aquarium, this will prevent it trying to claim the entire aquarium as its own and should reduce territory problems.

Feeding

Rainbow Sharks aren’t fussy eaters and will consume most things; providing it sinks to the bottom of the tank!  They will eat flake food, frozen food, pellets, vegetables and live food with no complaints.  Try to keep their diet varied and feed them a variety of food sources, similar to what they would eat in the wild. For instance: algae (tablets or wafers), insect larvae, crustaceans (frozen or live) and zooplankton. Also offer them plenty of vegetables such as spinach, lettuce, marrow (zucchini) and peas; this will keep their immune system strong.  To keep their red/orange color a vibrant shade, regular meals of live and frozen meat should be given to them such as frozen bloodworms and brine shrimp.

Care

When Rainbows are stressed you will notice their colors start to fade.  Sudden changes in the pH level can cause them to become more aggressive than usual.

See Fish Disease Diagnosis and Treatment at Rebel Pets for help with diagnosing and treating diseases.