We’ve all seen those huge schools of fish that move as one and coordinate their movements so perfectly. New research has come up with a way to map the chain of direct interaction in such schools of fish, discovering that the fish pay attention to one or two of their neighbours at a time when the school moves as a group.

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.

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.

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 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.

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.

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.

This is just one of the fascinating results from research using acoustic tags which has yielded new insights into what cod get up to below the surface of the sea.

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.

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.