Lionfish: Master of the show or Master of disaster?

Lionfish is undoubtedly a spectacular fish and often a highlight in our dives.
Very photogenic, beautiful and slow, it is the favourite creature of most of the underwater photographers.
From the time that the first Lionfish has been spotted on Rhodes (August 2014) until the present day, their numbers increased dramatically.
Is Lionfish a sign of reborn of the Reef or is it a sign of a dark future for local ecosystems?

Who is this stranger? 
Here are some facts:

Lionfish (Pterois volitans) is a carnivorous fish native to the Indo-Pacific.
It is also known as Zebra fish, Fire Fish and in other places of the world the free translation of local languages give those creatures more names (turkeyfish, flagfish etc.).

The closest relative for the lionfish in Mediterranean is the Scorpionfish or Stonefish.

Size and Weight:

An adult lionfish can grow as large as 45cm, while juveniles may be as small as 3cm or less. An adult weighs about 11kg in extreme cases. The usual size for individuals found in the coastline is between 10 and 20cm.

Appearance:

The lionfish’s head and body are brightly striped with brown and/or and white stripes. They have fleshy tentacles above their eyes and below their mouth, and long, fanlike pectoral fin. 

They have 13 long, separated dorsal spines. Their distinctive appearance is a warning to potential predators that the lionfish’s grooved spines are equipped with venom, which can cripple a predator and even harm a human. 

The venom of the lionfish is a defensive adaptation and is not used to catch prey.

Diet:

Lionfish are nocturnal predators that actively feed at night. They are ambush feeders that lay motionless on the bottom or between cracks until prey ventures close. 

Then, with a quick strike, they dart at their prey. Lionfish eat any animal smaller than the size of their mouth, including smaller fish, crabs, shrimp and even their own specie. In general they eat everything that moves infront of them. They are voracious creatures. They will stop eating only when there is no more space in there belly and mouth.
This is the main problem after all. That their unusually appetite is the reason that the local reefs are stripped of native marine life. 

Habitat:

Lionfish are most often found in marine habitats. They usually dwell in the warm marine waters of the tropics, but a massive invasion has taken place in sub tropic seas as well. Lionfish have been found in water depths from 1 to 100 meters on every kind of environments, rocky bottoms, cracks and caves, wrecks and artificial reefs and in general whenever they can hide and ambush.

Geography:

They are native to the South Pacific and Indian Oceans. They have a very large range that expands from the Red Sea across the Indian Ocean to Australia and the Pacific. Lionfish have recently been reported along the southeastern Mediterranean from Israel to Adriatic Sea. 

Breeding:

Males mate with several females during mating. After the fish spawn, they rise to the top of the water column and release gelatinous balls of eggs each containing about 2,000 fertilized eggs. The egg balls dissolve after about 24 hours, releasing the individual eggs which hatch in about 36 hours. A female Lionfish can lay eggs every 2 to 4 days. 

While thousands of eggs hatch, very few young fry survive to maturity. The young immediately begin feeding on the available plankton or newly hatched brine shrimp. At birth, they are almost transparent. They develop the vibrant stripes of adults as they mature.

Social Structure:

Lionfish are solitary creatures except during breeding.
Lifespan:

Their lifespan in the wild is unknown but they live approximately ten years in captivity.

Threats:

Lionfish have no natural predators. They are not currently listed as threatened or endangered in their native range. In some areas, they are considered an invasive species. However, the increase in pollution in reefs may negatively affect the lionfish’s primary food sources. If lionfish are unable to adapt to declines in their prey species, their numbers may decrease.

Summary:

The lionfish is widely regarded as an invasive species. They have the potential to harm reef ecosystems because they are a top predator that competes for food and space with overfished native stocks like snapper and grouper. 

Scientists fear that lionfish will kill off helpful species like the algae-eating parrotfish, allowing seaweed to overtake the reefs. In Greece, the lionfish population continues to grow and increase its range. Their increase is due to the lack of natural predators and their high reproduction rate.
A beautiful fish multiplies with unbelievable range, that is eating everything around it, disturbing the natural balance of local ecosystems, a creature that will soon change the reefs the way that we know them today.

A master of the show or a master of disaster?