A fascinating journey to discover the boxfishes & cowfishes of Mauritius. These fishes get their name from their cubic shape and have no scales. However, their various fins allow them to hover in place, swim backward, and even make sharp turns.

When stressed, they produce a toxin that makes them unsafe for consumption. They are protogynous hermaphrodites, meaning they are born female and can transition to male if necessary.

In Mauritius, you can find Ostracion cubicus (yellow boxfish), Ostracion meleagris (guineafowl boxfish), Lactoria cornuta (longhorn cowfish), and Ostracion trachys (hard-skin boxfish).

Ostracion cubicus (Yellow boxfish)

Introduction:

Mauritius, famous for its paradisiacal beaches and crystal-clear waters, is also a true sanctuary for marine life. Among the underwater treasures that can be discovered, boxfishes occupy a special place. These fascinating creatures, which include species such as Ostracion cubicus, Ostracion meleagris, Lactoria cornuta and Ostracion trachys, stand out for their unique shapes and bright colors. Let's dive into the mysterious world of these boxfishes and discover their way of life, habitat, and the challenges they face.

Description:

Lifespan and Size:

Boxfishes are known for their longevity, with a lifespan of up to 10 years in the wild. The size of these fishes varies by species. Ostracion Cubicus, also known as the yellow boxfish, can reach a length of 45 centimeters. Ostracion Meleagris, or the spotted boxfish, is slightly smaller, measuring about 30 centimeters when fully grown. Lactoria Cornuta, nicknamed the cowfish because of its prominent horns, can reach a length of 50 centimeters. As for Ostracion Trachys, also known as the rough-skin boxfish, a less well-known but equally fascinating species, it generally reaches a length of about 20 to 30 centimeters.

Diet:

Boxfishes are omnivores with a very varied diet. They primarily feed on small invertebrates, mollusks, crustaceans, and algae. Their diet can also include small fishes and sponges. Thanks to their powerful beak, they can crush the shells of mollusks and the carapaces of crustaceans, allowing them to effectively feed on these prey.

Habitat:

Boxfishes are generally found in coral reefs, where they find both shelter and food. They prefer warm, shallow waters, making Mauritius an ideal habitat for these species. They are often found at depths ranging from 1 to 50 meters, exploring reefs and lagoons in search of food. Their unique shape and bright colors allow them to blend into the coral environment, protecting them from predators.

Reproduction:

The reproduction of boxfishes is a fascinating and complex process. These fishes are oviparous, meaning the females lay eggs that hatch outside their bodies. Spawning usually occurs in the shallow waters of coral reefs. After fertilization, the eggs are left on their own, floating freely until they hatch. Boxfish larvaes are planktonic at the beginning of their life, drifting with ocean currents before settling into coral reefs where they will grow.

Predators:

Despite their robust appearance and bright colors, boxfishes are vulnerable to several predators. Among their main enemies are large predatory fish such as moray eels and sharks. Boxfishes have developed several defense mechanisms to protect themselves. For example, they can secrete a toxin called ostracitoxin through their skin, which is toxic to other fish and thus deters predators. Additionally, their square and rigid shape makes them difficult to swallow by predators.

Lactoria cornuta (longhorn cowfish)

5 Fun Facts About Boxfish

1. Square Morphology: Unlike most fishes, boxfishes have a square and angular shape. Their name comes from this unique appearance, making them look like small floating boxes in the water.

2. Defensive Toxins: Boxfishes can secrete a powerful toxin called ostracitoxin. This substance is released through their skin when they feel threatened and is capable of killing other fish in their immediate environment.

3. Changing Colors: Some boxfishes, like Ostracion Cubicus, can change color depending on their mood or environment. This dynamic camouflage helps them avoid predators and communicate with their peers.

4. Slow but Agile Movements: Although often considered slow swimmers due to their rigid shape, boxfishes can move with great agility using their pectoral and dorsal fins to propel and steer themselves with precision.

5. Celestial Appearance: Juvenile boxfishes, particularly Ostracion Cubicus, have patterns of bright blue spots on a vibrant yellow background. This appearance gives them an almost extraterrestrial look, making them resemble small cubes decorated with stars as they navigate the crystal-clear waters of coral reefs.

Ostracion meleagris female (guineafowl boxfish)

Ostracion meleagris male (guineafowl boxfish)

Conclusion:

The boxfishes of Mauritius, with their cubic shapes and colorful patterns, are natural wonders that deserve to be protected and celebrated. Their presence in the coral reefs of Mauritius adds to the biodiversity and ecological richness of the region. However, like many other marine species, they are threatened by the degradation of coral reefs, pollution, and climate change. Preserving their habitat is essential to ensuring their survival and allowing future generations to discover these magnificent creatures. By learning more about boxfishes, we can all contribute to their protection and that of their natural environment.

Note: once again big thanks to Visham and my friend Volker i.bins for agreeing to share their pictures on my blog :)