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Facts about the Giant Trevallie

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Description

All twenty-five species of trevally have elongated, compressed bodies and deeply forked caudal fins, with long, sickle shaped pectoral fins. The Giant Trevally (also known as the ulua, ronin jack and “GT”) is the most prized of the species by anglers and is identifiable by an ovoid patch of small scales located on the breast ahead of the ventral fins. Coloration for the Giant Trevally can range from silvery-white to almost jet-black.

The Giant Trevally uses its superior swimming abilities and power to hunt and smash baitfish. The Giant Treavally is known for stunning prey with its first strike and then circling back to engulf the wounded and/or disoriented baitfish. They will usually devour the prey quickly with one bite, as competition can be fierce from other members of the pack. As they grow, larger specimens move to deeper water and congregate over coral reefs and other underwater structure. Giant Trevally also venture onto flats, headlands and shallow water to hunt food. Giant Trevallies can be found along the reef edge and points where large pounding swells crash on the reef and rocks stirring up food and creating the ideal environment to hunt.

Pound for pound, these are among the hardest-fighting fish in the sea. The current record comes from a plug cast from shore in Japan. Fishing for trevally is best in hotspots like the Seychelles and the edge of the outside reef at Christmas Island, which is also a world-class bonefishing destination.

Average Length

23 inches – 5 feet

Average Weight

30 – 60 lbs

Habitat

The Giant Trevally ranges from estuaries to coral reefs. Juvenile fish are prevalent in estuaries and river systems.


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Range

Distribution is widespread. They’re found in the warm tropical waters of the Pacific and Indian Oceans as far south as New South Wales in Australia, east to the Hawaiian Islands, west to the eastern islands of Africa and north to Japan. You will find Giant trevallies on the dive sites around the Gili Islands. Specially Deep Turbo, Halik and Sharkpoint are famous for seeing the trevallies.
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Facts about Parrotfish

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When you are diving around the Gili Island you will spot them on every dive site. Some people loves them other one say this one of the most ugly fish in the sea. We are talking about the Parrotfish.

This herbivorous fish uses its strong beak-like mouthparts to scrape algae and other plant matter from the surface of the coral. This maintains the health of the reef by keeping algae in check, which could otherwise overwhelm the delicate reef ecosystem.

An unusual feature of parrotfishes is that they are able to change sex, with females becoming fully functional males. In a population, parrotfish start off as either females or males (known as primary males). Females may at some point in their life become male (secondary males). Populations that have these two types of males are called ‘diandrous’, meaning ‘two-males’. A terminal phase male defends a territory and a harem of females. If the male should die, the most dominant female will become the dominant male, her ovaries becoming functional male testes.

The parrotfish occurs in the western Atlantic, from Florida, Bermuda and the Bahamas to Argentina and the Gili Islands Indonesia.

Associated with coral reefs at depths of 3 to 25 metres. At night, parrotfish retreat into crevices. Juveniles tend to occur in mangroves adjacent to the reef. The mangroves act as important nursery areas and provide food-rich and predator free safe-havens for the growing young.

Facts about Batfish

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A lot of times you see them around when you are diving Sharkpoint, Gili Trawangan or Bounty Wreck, Gili Meno. Its the Batfish. They are so common when and we see then so many times around the Gili Islands, but what do we know about them?

Batfishes are recognisable on the basis of their distinctive shape, particulary juveniles, which have greatly elevated dorsal and anal fins. Other characteristics include a small, terminally located mouth, brush like jaw teeth (often with tricuspid lips), a continuous dorsal fin with 5-9 spines and 19-40 soft rays, anal fin with 3 spines and 17-29 rays, and typically a silvery adult colour pattern often with dark bars on the head and body.

Members of the genus Platax are extremely tame and curious, often approaching divers at close range.

Young fish are found close to the bottom, often around boat moorings, docks, jetties, and floating objects. Adults may form midwater feeding aggregation, frequently adjacent to steep outer reef slopes.

The diet consists largely of benthic invertibrates and zooplankton.

In their natural habitat the young of P. orbicularis mimic dead leaves, and those of P. pinnatus mimic toxic polyclad flatworms that are nearly identical in colour and shape.

Facts about Barracudas

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When you are diving around the Gili Islands you have a chance to see at the divesites Sharkpoint, Hans or Halik the Barracuda. Also in the evenings when you pass all the BBQ places for dinner, the barracuda is one of the most seen dishes. But how does it looks like?

Description

The great barracuda has a slender, streamlined body that is round in the mid-section. The top of the head between the eyes is nearly flat and the mouth is large, containing many large sharp teeth and a projecting lower jaw. The pectoral fin tips extend to the origin of the pelvic fins. The spinous and soft dorsal fins are widely separated and the double emarginate tail fin exhibits pale tips on each lobe. Body coloration of the great barracuda is brownish or bluish gray on the dorsum and upper side, with a greenish cast shading to silvery on the sides and a white belly. The upper side may have 18-23 dark bars most often observable when the fish is resting or over a variegated substrate. The black spots on the lower sides of the great barracuda distinguish it from other species of barracuda. The second dorsal fin, anal, and caudal fins are violet to black with whitish tips. Young barracuda exhibit pale reticulations on the dorsum and a dark stripe on either side that breaks into spots as the fish grows. These patterns are somewhat ephemeral though as juveniles can alter their color patterns to closely match that of their surroundings. These changes in coloration serve to camouflage the fish from predators as well as well as wary prey. Adults have similar coloration along with a more silvery appearance that is advantageous to a fish that swims near the surface of the water.

Habitat

Great barracuda commonly occur in nearshore coral reefs, seagrasses, and mangroves. They may also reside in the open ocean, living predominantly at or near the surface, although they are at times found at depths to 100 meters. Barracudas tend to be solitary but are sometimes found in small aggregations over reefs and sandy bottoms. Juveniles mature amongst mangroves and seagrass beds, habitats that offer cover from predators. During the second year of life, barracuda move to deeper reef habitats. Juveniles and some adults have been observed in areas that receive high amounts of freshwater input, however adults generally tend to avoid areas of brackish water.

Diet

Great barracudas feed on an array of prey including fishes such as jacks, grunts, groupers, snappers, small tunas, mullets, killifishes, herrings, and anchovies. Barracudas have a large gape and very sharp teeth, enabling them to feed on large fishes by chopping them in half. An opportunistic predator, great barracuda feed throughout the water column. Generally a diurnal fish, great barracuda locate their prey largely by sight. The body plan of the great barracuda is designed for speed and it is estimated that top speed for the species may be as fast as 60 km/h.

Fishery

Although not prized as a commercial fish in North American waters, the great barracuda puts up a good fight and is therefore esteemed by some anglers as a gamefish. They may be caught with a variety of gear including handlines, rod and reel, seines, trammel nets, and gill nets. The great barracuda has been implicated in cases of ciguatera poisoning within certain areas of its range. Ciguatera poisoning is caused by the bioaccumulation of ciguatoxins in the flesh of tropical marine fishes. Ciguatoxins are produced by marine dinoflagellates that grow attached to marine algae and as such may be incidentally ingested by herbivorous fishes. Large piscivorous reef dwelling fishes occupying the apex of the food chain become reservoirs for the highest amounts of ciguatoxin by feeding on other members of the reef community. Poisoned people report gastrointestinal maladies that may last several days, a general weakness in their arms and legs, and a reversal in the ability to differentiate hot versus cold. The illness is serious and symptoms may persist for weeks.

Size

Great barracuda are large fish. The record for a hook and line caught great barracuda is 1.7 meters, 44 kg and the species is reported to attain a size of 2 meters, 50 kg. Any barracuda over 4.8 feet (1.5 m) in length can be considered very large. Based on scale analysis of large specimens, great barracuda have a lifespan of at least 14 years. Sexual maturity is reached at a length of about 60 cm.

Range

Occurring worldwide in near shore tropical and subtropical seas (30°N – 30°S), the great barracuda is common in the western Atlantic Ocean from Massachusetts (U.S.) to Brazil. It is also found in the Gulf of Mexico and the Caribbean Sea as well as the eastern Atlantic Ocean, Indo-Pacific, and the Red Sea. It is rare or absent in areas of the eastern Pacific Ocean.

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Facts about Scorpion fish

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A scorpion fish is a group of predatory, marine fish that are found amongst coral reefs and in shallow waters in the more temperate oceans. The scorpion fish is most closely related to the lionfish and is most commonly found in the Indian and South Pacific oceans. You can find them if you dive around the Gili Islands at the dive sites Hans reef, Halik and the Bounty. Oceans 5 dive resort finds almost every dive a scorpion fish.

There are more than 200 recognised species of scorpion fish, hiding amongst the ocean reefs and in artificial aquariums around the world. Scorpion fish are kept in tanks by numerous people because of their interesting appearance and behaviour.

The body of the scorpion fish is often cover in feathery fins that help the scorpion fish to camouflage itself into the surrounding coral. The colours and markings of the scorpion fish are also used to help the scorpion fish to hide.

Scorpion fish are nocturnal predators, and spend the daylight hours resting in a hidden crevice in the coral. Scorpion fish are also able to ambush their prey from this position and often catch small fish by surprise.

Scorpion fish are omnivorous fish and hunt small fish, crustaceans and snails on the coral reefs. Scorpion fish are able to stun their prey with their venom before eating it. Scorpion fish also use their venomous sting to fend off unwanted predators.

The scorpion fish is a very dominant predator in it’s environment, and therefore the scorpion fish has very few natural predators. The human catching the scorpion fish to keep in tanks is the biggest threat to the scorpion fish along with habitat loss from the destruction of coral reefs. Large fish and sea lions are also known to hunt scorpion fish.

The female scorpion fish releases between 2,000 and 15,000 eggs into the water which are fertilised by the male scorpion fish. The scorpion fish pair then quickly hide so that their eggs can float into the ocean before being spotted by predators that eat the eggs. The scorpion fish eggs hatch in just 2 days and the tiny scorpion fish fry remain near the surface of the water until they are bigger. When the scorpion fish fry reach nearly an inch in length, they swim down into the ocean to join the reef community.

Facts about Damsel fish

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The Damselfish are quite lively and colorful and they are common in the tropical seas. They are found in the shallow water of tropical and semitropical seas, like diving around the Gili Islands and at the divesites Halik (North Gili Trawangan), Hans reef (North Gili Air) and Bounty Wreck (South West Gili Meno). They are small and aggressive. They love the coral reefs, mangroves and sea grass. They feed on zooplankton and algae. When they are in courtship, they make purring and clicking noises. The juveniles are different in color than the mature adults. Some juveniles may be red with blue spots. The mature ones are orange-yellow. They can display a ferocious behavior when they feel threatened. Some like to live in open water and swim in schools. These fish are beautiful as the display their bright colors.

Many of the Damselfish grow to a length of 7 cm. They become mature in two to five years. Some species may take much longer to mature. Their spawning season begins in spring and ends in the summer. There are a few different species and some species swim in large schools.

There are about 235 species of Damselfish, and that includes about 26 species of Clownfish. Habitat destruction and the destruction of the coral reefs may soon show declining populations.

The young Blue Damselfish can live together in peace, but they become very aggressive as they mature. They like to stay very close to the coral reef.

The Black and White Damselfish are also called Humbug fish. The Yellowtail Damselfish often lose their beautiful bright colors when they are captured. Some species of Damselfish can only be found in the Caribbean. Some species only live on the bottom of the sea and they defend their territory of about 16 feet. This territory covers feedinmg, spawning and shelter sites. The Damselfish ignores bass and groupers because they are much less competitive. It is the male that prepares for spawning by clearing a surafce of coral or rocky ledge. The female can lay up to about 20,000 oval eggs that are really tiny. The males guards these eggs with his fins. It takes the eggs about three to seven days to hatch.

If you like more information about diving around the Gili Islands visit our website: http//:www.oceans5dive.com

Sharkpoint Gili Trawangan, Gili Islands

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In a lot of dive destinations there are dive sites with names that only gives you as diver false expectations. There are Manta Points, Sharkpoints, Frogfish Points etc which doesnt offer what the name tells you. Sharkpoint on the Gili islands is not a dive site like that! Sharkpoint has his sharks!

Sharkpoint is the most famous dive spot around the Gili Islands. Its located on the West side of Gili Trawangan. A flat sandy bottom turns into a series of progressively deeper canyons that run parallel to the shore.

In the shallow part of Sharkpoint you will find for sure turtles in all kind of sizes. This will the Hawksbill and Green Sea Turtle. In the deeper part there is a good change to see the White Tip Reef Sharks, the school of Jack Fish and Baracudas.

Around full moon the Bumphead Parrotfish shows up from the deeper part of the ocean. This is one of the most beautiful moments that you as diver can have surrounded with 30 Bumpheads.

Sharkpoint is a dive site that is never boring, there is always a lot of marine life around. The dive site is suitable for all kind of divers.

Enjoy your dive!