Paracanthurus hepatus, commonly known as Blue tang, are tiny fish endemic to Indo-Pacific coral reefs. Male blue tangs are typically bigger than females, growing up to 12 inches long and 1.2-1.4 pounds in weight as adults. The renowned vibrant colors of the blue tang are not as consistent as you would expect.


Appearance

Blue tangs are distinguished by their royal blue body, yellowfin, and black palette form. The fish has a flat body, an elliptical form pancake-like, tiny scales, and a slightly tilted snout. For example, young blue tangs have a vivid yellow color.

A typical Blue tang swimming between corals and rocks
A typical Blue tang swimming between corals and rocks

Credit: Petr Kratochvil

In adulthood, the fish develop a dark blue and violet coloring as an indication of stress and constant threat.

Typical Blue Tangs can switch their colors to deep purple when exploring unfamiliar territory
Typical Blue Tangs can switch their colors to deep purple when exploring unfamiliar territory

Credit: Nathan Rubert

Due to the scalpel-like spines that run down the top and bottom of their bodies, blue tangs are categorized as surgeonfish. Sometimes the powder blue tang gets mistaken for the blue tang, with the main difference being a pronounced dark snout and light tail.

Diet

Plankton makes up the majority of its food as a juvenile. Adults graze on algae in addition to eating plankton since they are omnivores. Late afternoon and nighttime are prime times for spawning and therefore feeding. The fish nibble and chip algae off the coral reef with their tiny, pointy teeth. The shift in transition from a uniformly dark blue to a bright blue tint signifies this phenomenon. 

The fish is crucial for coral health because it consumes algae that would otherwise encroach and constrict the corals. A detrimental domino effect results from the absence of blue tangs and other fish that clear algae.

Habitat 

The crystal-clear waters on and near coral reefs are home to blue tangs. In order to protect themselves from predators, they build nests in tiny fissures and gaps in the reef, which are frequently found at depths between 10 and 130 ft. In these depths, snorkelers and scuba divers have a high chance of spotting them around. They live in a large geographic area that runs from American Samoa to the eastern coast of Africa in the Pacific and Indian Oceans. They may be spotted in the reefs of East Africa, Sri Lanka, the Philippines, Japan, Indonesia, and Australia’s Great Barrier Reef.

Paracanthurus Hepatus, a coral reef fish also known as a Pacific blue tang, contrasts sharply with the stony Acropora coral at one of the Pacific Remote Islands National Wildlife Refuge Complex
Paracanthurus Hepatus, a coral reef fish also known as a Pacific blue tang, contrasts sharply with the stony Acropora coral at one of the Pacific Remote Islands National Wildlife Refuge Complex

Credit: Jim Maragos/USFWS


Reproduction

Blue tangs engage in broadcast spawning, which is a method of reproduction where the males and females release sperm and eggs simultaneously into the surrounding water just above corals when they assemble in groups. This strategy enhances the possibility that fertilized eggs will survive fertilization and will not be consumed by egg hunters on the coral surface. Approximately 30-50,000 eggs are discharged each cycle.

Both males and females float away when reproduction is finished, leaving the offspring to care for themselves. The eggs hatch one day after fertilization. The larvae spend time in a plankton swirl, eating and developing until they are prepared to transform into juveniles. While dwelling on the coral, juveniles develop and change both their physical characteristics and dietary preferences until full maturation.

Threats

Environmental degradation and coral bleaching are two threats to the coral reefs that are home to blue tangs. As a result, fish could potentially be at risk of habitat destruction. Squirt bottles filled with cyanide are frequently used to catch blue tangs as well as other wild fish, as they are stunned long enough to be caught. However, using such an approach also runs the risk of killing the fish immediately and harming or killing other surrounding creatures.

Since the animated movies “Finding Nemo” and “Finding Dory” have made the fish an icon of pop culture, the demand for this fish as a pet has skyrocketed, resulting in hundreds of thousands of illegal removals from natural habitats. 

Facts about the Blue Tang 

  1. The blue tang has a 30-year minimum lifetime in the natural environment. However, blue tangs can survive for up to 20 years in captivity.
  2. Blue tangs have the ability to change the hue’s vibrancy from sky blue to dark purple.
  3. When under distress, blue tangs have the ability to extend a pair of razor-sharp, poisonous spikes along either side of their tails.
  4. Blue tangs are unfit for human eating. 
  5. Larvae or fry are the terms used to describe young blue tangs.


FAQs 

Are blue tang fish forgetful?

It’s improbable that the blue tang has a poor short-term memory. There really is no research to support the idea that any fish has a “three-second memory,” contrary to what people tell you anecdotally. 

Can a blue tang hurt you?

The blue tang is not an aggressive species per se; however, when threatened, they may raise stingers with poisonous tips and whirl their bodies in the water, threatening to stab any approaching predators.

How can you tell if a blue tang fish is male or female?

Although quite similar, the body of the blue tang male is longer, and the blue continues into the tail, while females are entirely blue with a transparent tail, and they also have a golden neck.

Why are blue tangs called surgeonfish?

They are known as surgeonfish due to the exceedingly sharp, movable spikes on either side of their tails that make them a good fit for surgical scalpels.

Synonyms:
Paracanthurus hepatus