There's no mistaking the hulking silhouette of a large bumphead wrasse bumbling in from the blue. This slow-moving and inquisitive fish, with its intricate facial markings and iridescent blue and green flanks, is a welcome sight on many dive sites. Known by many different names, this big-lipped gentle giant is one of the bulkier reef fish and can be found across the Indo-Pacific, occasionally reaching celebrity status. If you want to know more about these blue-green behemoths, here are our top ten bumphead wrasse facts, including the best places to enjoy their company...

1. Bumpheads Go by Different Names

The bumphead wrasse (Cheilinus undulatus) has a few different common names, including humphead wrasse, Māori wrasse, Napoleon wrasse and Napoleon fish. While the bumphead and humphead epithets are obvious, the Māori and Napoleonic references are more subtle.

If you get close to a bumphead wrasse, you will notice an intricate pattern on its face that resembles tā moko, the traditional Māori tattoos which often adorn the faces of the indigenous New Zealanders. Meanwhile, the Napoleon moniker is an ode to the bump on the fish's forehead, which resembles a bicorne, the style of hat traditionally worn by the former French Emperor.

2. It’s Not a Parrotfish

Occasionally, there is some confusion between the bumphead wrasse and the humphead parrotfish. Despite similar names and features - namely both having bumps on their foreheads - they are two distinct species belonging to different families.

The humphead parrotfish (Bolbometopon muricatum) is the largest parrotfish and is similar in colour and size to the bumphead wrasse. The key to telling them apart is to focus on the head: the parrotfish has a vertical face, while the wrasse has a sloping face. Also, the humphead parrotfish has the parrotfish's distinctive beak-like teeth, which are constantly on show.

3. Bumphead Wrasses Can Change Sex

The ability to change sex is reasonably common among aquatic critters, and bumphead wrasses are no different. They are protogynous hermaphrodites, meaning some females become male when they reach a certain level of maturity, at about nine years old.

4. Not All Bumphead Wrasses Have Humps

While the hump on the forehead is one of the fish's main distinguishing features, only males develop one. Another way to distinguish the sex is by the fish's colouration. Males range from a bright electric blue to green, purplish-blue or dull blue-green, whereas females are a red-orange colour with a pale or white underside.

5. How Big Are Bumphead Wrasses?

Sexual dimorphism, when sexes of the same species show different characteristics, is also present in the sizes of the male and female bumphead wrasse. Females are much smaller, growing up to around one metre in length, whereas males can grow to twice that size, which makes it the largest living member of the wrasse family.

6. How Long Do Bumphead Wrasses Live For?

Bumphead wrasses have quite long lifespans for fish, having been reported to live for over thirty years. On the Great Barrier Reef, a famous bumphead wrasse called Wally has been greeting divers on the reef for years. However, when Wally first started approaching divers, 'he' was named Sarah. At nine years of age, Sarah began to develop a hump and transition into a male. Today, Wally is still making his presence known on the reef.

7. What Do Bumphead Wrasses Eat?

One of our more niche bumphead wrasse facts is that they don't eat hard-boiled eggs. Or at least they shouldn't. In the past divers have hand-fed bumphead wrasses eggs, but this practice is now frowned upon as the fish struggle to digest the eggs. The bumphead wrasse's preferred diet includes molluscs, such as sea slugs, crustaceans and sea urchins.

They have also been seen smashing sea urchins against rocks to open them, and are known to eat crown-of-thorns starfish too, despite their toxicity.

8. Where to Dive with Bumphead Wrasse

Bumphead wrasses can be found along the east coast of Africa, including the Red Sea, Tanzania and Mozambique, across the Indian Ocean and in some areas of the Pacific Ocean.

Australia's Great Barrier Reef is a great place to see them, and you may even have an encounter with Wally himself. Other great places to dive with bumphead wrasses include the Maldives, in the Indian Ocean, and Palau and Micronesia in the Pacific.

9. Bumphead Wrasses Have an Unlucky Property...

Unfortunately, the bumphead wrasse is considered a delicacy in some parts of Asia, especially in Hong Kong. This has led to the overfishing of the species to feed the lucrative live seafood trade, and as such, the bumphead wrasse is no longer as common as it once was in Southeast Asian waters. However, this fish is protected in some places, like the Maldives and Australia.

10. Do Not Feed Bumphead Wrasses

While some countries have moved to protect the bumphead wrasse, they are still listed as endangered on the IUCN Red List and in Appendix II of CITES. However, more effort is being made to help the bumphead wrasse. In addition to gaining protection from illegal fishing in some locations, there has also been a decline in hard-boiled eggs.

In the past, dive guides often coaxed bumphead wrasses to divers with hard-boiled eggs, however, this has been banned in the Red Sea and Australia after postmortems revealed very high levels of cholesterol in the fish. Bumphead wrasses are naturally curious, although less so in areas where they have been extensively fished, and there's a good chance, should you encounter one, that it will come close enough for you to admire its Māori markings and Jagger-esque lips without the need for an unhealthy snack.