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TRIGGERFISHES (Balistidae)
A moderately large family, common to our area and often encountered around the Similan Islands. Large-headed fishes,
first dorsal fin with 3 spines, of which the first is stout and
lockable in upright position by second spine. Pectoral fin usually
small and paddle-like. Their jaws are very strong, each with 8 long
close-set teeth.
Most species are distinctly colored and readily
identified. In most species there is virtually no difference between
sexes. Males of some species are known to make nests and guard eggs
vigorously, often attacking divers which venture into their territory.
To escape danger, trigger fishes use narrow holes or ledges in which
they wedge themselves head inwards, with the trigger dorsal spine
locked in upright position, making it very difficult to be pulled
out. Diet comprises of hard-shelled molluscs and echinoderms.
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 Length:
to 80 cm
The largest triggerfish and one which can be very aggressive
when guarding nests but may attack divers for no obvious reason.
Best to swim around large individuals at distance, rather
than crossing its area. Usually seen singly on costal slopes
near to deep water. |
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FILEFISHES (Monacanthidae)
A large family of small to medium sized fishes. Most species change
in shape with age, juveniles may be almost circular and very compressed,
whilst adults are very elongate.
The body is covered by tiny prickly
scales, forming a tough leathery or velvet-like skin. A prominent
and separate first dorsal fin spine is an obvious feature in most
species. In nearly all species the spine is lockable in an upright
position.
Most of the reef species are distinctly colored or shaped
and identification usually is easy. Most are greenish and a great
number of species associate with weeds or sea grasses in which they
camouflage.
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 Length:
to 1 m
Largest family member with a distinct script pattern. A shy
and solitary species, only rarely seen in groups.
Like some
of the trigger fishes, this filefish species sometimes feed
on medusas.
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PUFFERFISHES (Tetraodontidae)
Their common name applies to their ability to inflate themselves
to almost balloon proportions to deter predators. In addition many
species are prickly when inflated and become even more hazardous
to consume. All species are poisonous in either internal organs
or skin toxins, giving a clear message: leave me alone. With some
species diet includes almost everything whilst others have preferences
for certain invertebrates or algae, but all seem to consume a great
variety.
Closely related to the puffer fishes are the PORCUPINEFISHES
(Diodontidae). They are similar in their ability to inflate themselves
to considerable size, but have in addition large spines which point
outwards when inflated. Their teeth are totally fused into beaklike
jaws.
Also closely related to puffer fishes are the BOXFISHES (Ostraciidae).
The body is largely covered with well defined hexagonal bony plates,
fused into a ridged case with holes for the moving parts, the fins,
mouth, eyes and gills. The surface of box fishes is smooth but some
have prominent spines above eyes or back. The body is covered with
toxic mucus, which deter predators but also the toxin is released
when under stress, killing other fishes or themselves if kept confined.
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 Length:
to 30 cm
This species mainly lives on coral reefs, often sleeping in
barrel sponges.
Highly variable, gray to brown or bright yellow, black
spotted to various degrees. Occurs singly or in pairs.
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 Length:
to 1,2 m
Largest of all puffer fishes, encountered to 60 m. Prefers
reefs with caves and large sponges, usually seen singly.
Feeds
on invertebrates, mainly echinoderms. |
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 Length:
to 70 cm
This species inhabits coral or rocky reefs, usually seen singly,
often swimming high above the substrate during the day.
Feeds
on invertebrates, mainly shells and molluscs.
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 Length:
to 16 cm
Pairs are often seen swimming together at the Similan UNational Park, at a distance of up
to 20 m. Males impress by their colorful coat.
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ANGLERFISHES (Antennariidae)
This family is unique in having a peculiar luring apparatus above
the mouth, usually a modified first dorsal spine, which is specialized
in each species by mimicking the food-source of its prey. So the
potential victim sees its favorite food, which in reality is a copy
in looks and motion. What appears as an easy meal, lures the victim
closer where it becomes a meal itself.
Anglerfishes don’t just
position themselves anywhere, but choose a spot where prey is likely
to come along. The tropical species primarily feed on other fishes
and with their expandable stomach can accommodate any large prey
which passes through the mouth.
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 Length:
to 24 cm
A very common but one of the most variable species, virtually
appearing in all colors but blue and green, matching most
sponge colors.
Inhabits coastal reefs, lagoons and slopes
with corals, sponges or at night just out in the open on sand. We see them often in the Similan Islands and around Phi Phi Island.
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LIZARDFISHES (Synodontidae)
A primarily tropical family, comprising about 40 species worldwide.
Most are reef predators, featuring a torpedo shaped body, a large
mouth with long needle-like teeth along entire jaws to seize prey.
On tropical reefs they rest on top of reefs, strategically chosen,
to view the area for possible prey. Camouflaged and waiting motionless
in ambush, with lightning speed a careless fish is taken. Usual
prey is juveniles of larger reef dwellers. Most species are found
near reefs on sand, reef crests or rubble slopes, sometimes burying
in the substrate.
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 Length:
to 25 cm
By far the most common reef dwelling lizardfish.
Mostly resting
on hard substrate, including live coral and sponges, singly
or in pairs.
Variable color, banding from dull grey to bright
red.
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