Fish

In 2023, DNA analysis found the houting to be genetically indistinguishable from Coregonus lavaretus, the common European Whitefish,and therefore not extinct.
In 2023, DNA analysis found the houting to be genetically indistinguishable from Coregonus lavaretus, and therefore not extinct.

The Houting's Remarkable Return: Not Extinct After All

The Houting fish, believed to have vanished from our waters, has made an unexpected return. Previously listed as 'extinct' on the IUCN Red List of Species, recent research has unveiled that this fish is not only thriving but is also not a distinct species as once thought.

The hogfish, also known as boquinete, doncella de pluma or pez perro in Mexico is a species of wrasse native to the Western Atlantic Ocean
The hogfish, also known as boquinete, doncella de pluma or pez perro in Mexico is a species of wrasse native to the Western Atlantic Ocean

Light-sensing Skin Cells Make Hogfish a Master of Camouflage

Hogfish, Lachnolaimus maximus, possess an uncanny ability to alter their skin colour, transitioning from a mottled white to a deep coral orange within mere seconds. This remarkable transformation is a survival mechanism, allowing them to seamlessly blend with their environment, evading potential predators.

When the trumpetfish swims alongside another species, it either remains hidden or is not recognised as a threat due to its altered shape
When the trumpetfish swims alongside another species, it either remains hidden or is not recognised as a threat due to its altered shape.

The trumpetfish's unique hunting strategy

The trumpetfish, with its long, slender body, shadows non-threatening species like the parrotfish. This allows it to get closer to its prey, such as damselfish, without being detected. Dr Sam Matchette, a leading researcher from the University of Cambridge, explains that when the trumpetfish swims alongside another species, it either remains hidden or is not recognised as a threat due to its altered shape.

Tetra fish
Tetra fish

Neon tetra fish wait their turn when evacuating through narrow opening

Scientists have observed neon tetra fish queuing up when exiting through a narrow opening, according to a study in the journal Scientific Reports.

In the study, Aurélie Dupont, a biological physicist in the Laboratoire Interdisciplinaire de Physique at University Grenoble Alpes, and her team set up two fish tanks connected to each other by a narrow opening. The diameter of the passageway varied from 1.5 to 4 centimeters.

A research team has demonstrated that fish think "it's me" when they see themselves in a mirror or picture.

Fish recognises itself in photographs

A new study demonstrates how animals recognise self-images.

Some animals have the remarkable capacity for mirror self-recognition (MSR), yet any implications for self-awareness remain uncertain.

In a test of MSR ability in cleaner fish, mirror-naive fish initially attacked photograph models of both themselves and unfamiliar strangers. In contrast, after all fish had passed the mirror mark test, they did not attack their own (motionless) images, but still frequently attacked those of unfamiliar individuals.

Lionfish invades Brazilian waters

First spotted in the Atlantic Ocean off Florida in the 1980s, they later spread across the Caribbean, reshuffling coral reefs and other ecosystems by feasting on fish unfamiliar with the voracious predator.

While ocean currents that flow north—such as the South Equatorial Current—and the freshwater plume created by the Amazon River hampered the spread of the invasive species, scientists predicted it was just a matter of time before it moved into Brazilian waters.

Why damselfish chasing away cleaner fish's customers is bad for reefs

Many of us are familiar with the scenes at cleaning stations, where cleaner fish and cleaner shrimp feed on the parasites and dead tissues of their “clients.”

Under normal circumstances, sharknose gobies (Elacatinus evelynae) would set up a cleaning station at a coral reef, and use it as a base to attend to their “clients”—usually the parrotfish, surgeonfish, butterflyfish, etc— by eating the parasites and dead body tissue off their client's skin, fins and mouth. 

However, at reefs with damselfish, things are not always so peaceful.

Masked spinefoots (S. puellus)
Masked spinefoots (S. puellus)

Fishes look out for their buddies

In pairs of coral reef rabbitfishes (f. Siganidae), one fish frequently assumes an upright vigilance position in the water column, while the partner forages in small crevices in the reef substratum. Both behaviours are strongly coordinated and partners regularly alternate their positions, resulting in a balanced distribution of foraging activity.

Claire Paris (second from left) and co-author Jean-Olivier Irisson (third from left), deploying the Drifting In Situ Chamber (DISC), equipped with an imaging system, during an expedition at the Australian Museum Lizard Island Research Station
Claire Paris (second from left) and co-author Jean-Olivier Irisson (third from left), deploying the Drifting In Situ Chamber (DISC), equipped with an imaging system, during an expedition at the Australian Museum Lizard Island Research Station

Fish larvae use external clues to find their way

In this study, researchers discovered that fish larvae around the world used external cues like the sun, Earth’s magnetic field and sounds to find their way around in the open ocean. 

The fish larvae were able to control their destination and migrate by keeping a bearing.