Juvenile Fish in the Lagoon Blackeye Thicklip Wrasse or half-and-half Wrasse (Hemigymnus melapterus)

I love to escape to the lagoon and our beautiful underwater world. I enjoy snorkeling in the warm water in the Kingston lagoon at Slaughter Bay and Emily Bay. I have written many articles about fish and coral and this week I will write about the lovely small fish I have photographed during December, January and February in Slaughter Bay.

During my final Snorkel for 2024, I spotted a small fish I have never scene before, it stood out because it had a grey front of its body and back half was brown or a darker colour and a bright orange tail. This lovely young fish lives on the coral reef in Slaughter Bay and the first images I took were on 31 December 2024 and this little fish along with another is still on the same coral reef in lagoon this week.

When I research the fish, I learnt that this juvenile fish is named Blackeye Thicklip (Hemigymnus melapterus) or Half & Half wrasse juvenile fish. I have posted a couple of photos on the i-naturalist citizen science page and local snorkeller Susan Prior has also posted images of fish she has found in the Kingston lagoon of this lovely little fish.

I have found two colour stages of these juvenile wrasse fish, they were feeding in the coral reef and have stayed in the same areas for a few weeks, which is interesting to watch them grow. The first juvenile stage is the fish that is shades of green in colour with a pale-green to white coloured diagonal band and the same big black eye. The second juvenile stage was the first fish I found was the grey front and dark back with white diagonal band and orange tail. Researching about the fish, I have learnt this is the next stage of growth development, but I have not found the adult Blackeye Thicklip half-and-half wrasse, but I will keep looking, you never know what I might find next in the lagoon.

I have included photos I have taken, but a collection of fish images of the adult fish I saw on i-naturalist internet citizen science online links.

https://www.inaturalist.org/observations/256868144

https://www.inaturalist.org/taxa/102580-Hemigymnus-melapterus

The blackeye thicklip wrasse or half-and-half wrasse (Hemigymnus melapterus) is a species of fish belonging to the wrasse family. It is native to the Indo-Pacific.

Description

The half-and-half wrasse is a medium-sized fish that can reach a maximum length of 50 cm.

Its body is high, relatively flattened, its head is large, and its terminal mouth has thick lips. Its body coloration varies according to age. Juvenile wrasses have a greenish yellow background colour with yellow vertical lines, a broad white diagonal band just behind the operculum, an orange caudal fin and a greenish grey front. Mature females are green behind the oblique line, with black-rimmed scales. A complex tangle of pink lines underlined with turquoise crosses from the top of the snout to the head. Mature males (terminal phase) also have an emerald - green stripe behind each scale and a blue rim around the eye; the top of the snout and head are green with pink patterns highlighted in turquoise.

Distribution and Habitat

The species is widespread throughout the tropical and subtropical waters of the Indo-Pacific, from the eastern coast of Africa including the Red Sea to Polynesia, and from New Caledonia to southern Japan. It prefers areas of coral, coral rubble and sand, outer reef slopes and drop-offs, to depths of at least 40 m. Juveniles are more secretive and always keep hidden in branching corals.

The half-and-half wrasse lives solitary or in small groups. It is a benthic predator that feeds mainly on small marine invertebrates such as crustaceans, molluscs, worms and echinoderms captured on or in the substrate.

In addition to picking food off coral branches, it may take in mouthfuls of sand, sorting out food items in the mouth and then expelling the sand through the gill operculae.

Like most wrasse, it is a protogynous hermaphrodite, i.e. individuals start life as females with the capability of turning male later on.

Conservation status

The species is targeted but not thought to be threatened by the aquarium trade and is being sought as a food fish and by spear fishers. It is present in several large protected areas, and currently listed as Least Concern (LC) by the IUCN.

If you get a chance to go snorkelling, come down to the bay and enjoy a swim and our underwater world. I always enjoy snorkelling at low tide in the water at Kingston. If you are unable to swim, it is worthwhile spending some time on the glass bottom boats and the timetables are on the signs next to the tractors at the far end of Emily Bay or available from the Information Centre in town.

Remember if you are swimming and snorkelling it is important to care for the reef and coral environment. The corals have so many colours and shapes and the fish are so friendly, and they follow you about hoping you may have something for them to eat. Please remember not to feed the fish, they have their natural food. Do not stand on the coral, as this can damage the corals which are living creatures. Also remember to care for yourself, with sun protection, I prefer to use a swimming vest instead of sunscreens.

The snorkelling here on Norfolk Island is so relaxing and enjoyable. It is the place to see all the beauty below the water and it is the world I love to capture on my camera. Here are a few underwater photographs of the lovely juvenile fish, Blackeye Thicklip Wrasse or half-and-half Wrasse (Hemigymnus melapterus).

Happy Summer Snorkelling Yorlie

Betty Matthews

14 February 2025