Meet the cave-dwellers

Blotcheye soldiers (Myripristis murdjan) are small, vividly red fish with large eyes, black gill covers, and white edges on their fins. These fish grow up to 27cm and are typically found around coral reefs throughout the Indo-Pacific, particularly on the east coast of Africa. 

Blotcheye soldiers are nocturnal predators and can be found hiding in caves and under ledges during the day. At night, their red colouration serves as camouflage in open water - they use this element of surprise to hunt small crustaceans, zooplankton, and fish. 

Crown squirrelfish (Sargocentron diadema) are bright red, with many silver stripes running horizontally across their bodies. They have pronounced spines in their fins and gill covers - these can be raised if threatened.

These beautiful fish grow to 21cm and are found hiding in caves in coral reefs, lagoons, and rocky reefs throughout the Indo-Pacific. At night, they use their red colour as camouflage in the darkness to hunt for zooplankton.

These fish are dubbed "cave dwellers" because they spend their days hidden in caves and their nights hunting in the open waters. Here's why: 

One of the most visible traits of both the crown squirrelfish and blotcheye soldier is their red colour. The colour red is predominant in many ambush and predatory fish species. This is because red is the first colour to be absorbed from the light spectrum underwater. This means these fish are nearly invisible to their prey in low light. 

When these cave dwellers go hunting, their dark colours (combined with their ability to detect the smallest electrical signals in the water around them) make them almost impossible to avoid. 

You'll notice that these cave dweller fish have relatively large eyes - this is because they are adapted for life in low light conditions, which contributes to their ability to hunt at night.