Paracanthurus hepatus = (royal) blue Tang
Vergleich: Siehe: Pisces
[Louis Klein/Carol Jones/Judith Mapleson]
The fish has a royal blue body, yellow tail, and black 'palette' design and can grow to 30 cms long.
Blue Tang can communicate by changing their colouration. Under stress, their blue coloration can deepen. The black marks along the body may become bleached
(sometimes referred to as semi transparent) and the markings less visible.
The iridiphores causing the bright blue coloration at this time appear smaller and less iridescent, hence the darker shade of blue. Color change also occurs during stimulation such as male
dominance interactions or breeding.
The blue tang is a high bodied, compressed, pancake shaped fish, with a circular body shape, a pointed snout like nose, and small scales. The eye located high on the head
and the mouth is small and low on the head. The blue tang has 9 dorsal spines, 28 dorsal soft rays, 3 anal spines, and 24 - 26 anal soft rays.
A distinct yellow caudal spine is located at the base of the tail on either side of the body which resembles a surgeon’s scalpel (Surgeonfish)
The spine fits into a horizontal groove and can be extended and used to fend off aggressive encounters.
The dorsal fin is continuous.
Habitat: clear, current swept terraces of seaward reefs.
Juveniles are seen in groups near isolated Pocillopora eydouxi coral heads and when alarmed hide themselves tightly among the branches
The species' range is broad and can be found throughout the IndoPacific.
They live in pairs, or in small groups of up to 10 or 12 individuals
Uses and Collection: The Blue Tang has minor commercial importance; its flesh has a very strong odour and so is not highly prized. It is a very popular aquarium fish.
The Philippines were the primary supplier.
Irresponsible collecting include using cyanide to capture the fish from their black coral refuge and also the removal of the coral heads where the fish seek shelter has limited their numbers.
The fish are captured by a type of net termed a “fence”. A barrier is set up 10 - 30 feet away in a Ushape and the specimens are chased into the net when they leave their coral nest.
Life cycle: Spawning occurs in the late afternoon or at dusk usually in February or March.
Males aggressively court female members of the school, leading to a quick upward spawning rush toward the surface of the water during which eggs and sperm are released. This event is
indicated by a change from dark blue to a pale blue, and results in the production of small floating eggs. The eggs are small, approx. 0.8 mm in diameter, they are pelagic drifters each containing
a single droplet of oil for flotation. The eggs hatch in 24 hours and produce small translucent larvae.
The Blue Tangs diet consists primarily of plankton. Adults are omnivorous and they use their beak like mouth in the wild to consume zooplankton and scrape algae from their environment.
They will eat small crustaceans such as mysids shrimp and krill. The fish reaches sexual maturity in 9 - 12 months of age and can live up to 20 years.
It is susceptible to parasitic diseases and they also suffer if their diet is inadequate. Common diseases are marine itch and marine velvet, hole in the head disease, and lateral line erosion.
Defence: Blue Tangs are very timid.
They have a strange tendency of lying over on their sides and playing dead when they feel threatened. If they feel cornered or attacked they can extend the spines located on both sides of the
caudal peduncle as a method of protection.
The quick, thrashing sideways motion of the tail can produce deep wounds that result in swelling discoloration and pain.
More than one Blue tang in a small aquarium or more than one male in a larger tank can cause stress and stimulate aggression, can lead to injury of the fish from fighting.
The Blue Tang is regarded as a playful fish, chasing bubbles in the aquarium and even playing with snails and small objects in the tank.
The Blue Tang is regarded as venomous. Not many piscine types of venom have been analyzed but their most potent effect the cardiovascular system. This includes the release of nitric oxide
or other agents from the endothelial cells these have a depolarizing effect on nerve and muscle cells and smooth muscle contraction occurs.
The potent cytolytic activity of most piscine venoms is likely the mechanism that causes cardiovascular and neuromuscular effects.
The Blue Tang can cause Ciguatera. in humans when consumed.
Dinoflagellates are a type of zooplankton and they adhere to coral, algae and seaweed and are a common source of food for Blue Tang.
Popularization: The Blue Tang would have to be one of the most common and most popular Marine Fish all over the world.
Film “Finding Nemo”
A pacific blue tang named Dory was popularized in the 2003 Disney film finding Nemo. It tells the story Marlin who, along with Dory searches for his abducted son Nemo.
Marlin gets Dory, naïve but good hearted and optimistic, with short term memory loss to help.
After becoming trapped in a whale’s mouth , Dory breaks down in despair but then reassures Marlin and calmly tries to communicate with the whale.
She then loses her memory and becomes confused, but meets Nemo, who has escaped into the ocean.
Dory's memory is suddenly restored after she reads the word "Sydney", and guides Nemo to Marlin. After the two joyfully reunite, Dory is caught in a fishing net among a school of grouper. Nemo enters the
net with bravery and directs the group to swim downward to break the net and the fish escape.
Master Provers: Louis Klein, Carol Jones and Judith Mapleson
The Hahnemanian Proving was conducted through Lou Klein’s HMC course in February 2011.
There were 8 provers, 3 supervisors.
Source of Material Blue Tang was sourced and run up by Robert Müntz of Remedia Pharmacy in Austria.
The source was equal parts of the fins and flesh of the fish.
Blue Tang Themes
Remembering the past, Memories
Family, Relationship problems
Reluctance to Communicate/communication
Drugged, Dazed, Disoriented
Desire to Protect, Hide,
Resist Authority, Running, Hiding
Depression/Joy (laughing, singing, dancing)
Pregnancy, Labour, Babies