Atherinomorus lacunosus (Forster, 1801)

English Name: Hardyhead silverside
Family: ATHERINIDAE
Local Name: Hithiboa
Order: Atheriniformes
Size: Max. 15 cm
Specimen: MRS/0486/97

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Distinctive Characters: Distal end of upper jaw extending backward to vertical through anterior border of pupil. Dentary bone sloping upward and backward, but never elevated posteriorly. Anterior edge of preopercle with a distinct notch above angle. Midlateral scale count 39-44.

Colour: Greenish-grey on back, the scale edges dusky. A silvery stripe on side, its upper edge with an iridescent blue line. Live fish translucent.

Habitat and Biology: Occurs in large stationery schools near the shore during the day. Feeds mostly at night on planktonic eggs, crustaceans and small fish.

Distribution: Indo-Pacific.

Remarks: Atherino,norus lacunosus is one of the two silverside species that are sometimes used as live bait by Maldivian tuna fishermen. Although it gives a good initial chumming response, the tunas soon stop feeding. The reason for this appears to be the silversides tough scales and bony body, which the tunas find indigestible. As a result, many tuna fishermen oppose the used of silversides as bait.

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Trachinotus blochii (Lacepède, 1801)

English Name: Snuhnose pompano
Family: CARANGIDAE
Local Name: Rindha vaali
Order: Perciformes
Size: Max. 80 cm
Specimen: MRS/P01 11/87

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Distinctive Characters: First dorsal fin with 6 spines, second dorsal with 1 spine and 18-20 rays. Anal fin with 2 detached spines followed by I spine and 16-18 rays. Body oval shape and compressed. Tongue toothless. Predorsal bone oval-shaped. Profile of snout broadly rounded. No scutes.

Colour: Silver, but often washed with golden-orange, especially in larger individuals. Anal fin dusky orange, and lobe with a brownish anterior margin.

Habitat and Biology: Inhabits coral and rocky reef areas and shallow coastal waters at depths of 2-20 m. Feeds mainly on molluscs and hermit crabs which it crushes with its strong pharyngeal plates.

Distribution: Widely distributed in Indo-West Pacific.

Remarks: Trachinotus blochii is not very common, but it is occasionally caught by hand line, and is sometimes seen by divers, in small groups along the outer reefs. The Dhivehi word rindha ‘means mussel, and refers to the oval shaped bone to be found just under the skin at the nape of ‘neck’.

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Sufflamen fraenatus (Bloch and Schneider, 1801)

English Name: Brown triggerfish
Family: BALISTIDAE
Local Name: Mushi rondu
Order: Tetraodontiformes
Size: Max. 38 cm
Specimen: MRS/041 1/92

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Distinctive Characters: Dorsal fin with 3 spines and 27-31 rays. Anal fin with 24-28 rays. Pectoral fin with 14-15 rays. Cheeks scaled. Deep groove in front of eye. Longitudinal scale ridges on posterior part of the body extending forward to the middle of the body. Caudal fin rounded in young, truncate to slightly emarginate in adults.

Colour: Brown to pale brown with a pale yellowish ring around mouth and a narrow pale yellowish band across chin. Juveniles with longitudinal dark brown lines.

Habitat and Biology: Usually seen in depths greater than 25 m. Feeds mainly on sea urchins, heart urchins, brittle stars, fishes, bivalve molluscs, tunicates and crustaceans.

Distribution: Indo-Pacific.

Remarks: Sufflarnen fraenarus is a somewhat deep dwelling species, being apparently most common in atoll basins. S. capistrarus Shaw, is a synonym

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Sufflamen bursa (Bloch and Schneider, 1801)

English Name: Boomerang triggerfish
Family: BALISTIDAE
Local Name: Dhon falhu rondu
Order: Tetraodontiformes
Size: Max. 20 cm
Specimen: MRS/0345/89

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Distinctive Characters: Dorsal fin with 3 spines and 27-29 rays. Anal fin with 25-27 rays. Pectoral fin with 13-14 rays. Dorsal and ventral profiles of head nearly straight. Cheeks scaled. Prominent groove in front of the eye. Longitudinal scale ridges on posterior part of the body extending forward to the middle of the body. Caudal fin truncate to slightly rounded.

Colour: Greyish brown, pale below. A white line from corner of mouth to anal fin origin. Two dark curved bars posteriorly on head which may be either yellow or black.

Habitat and Biology: Usually in reef flats and reef slopes. Omnivorous, feeding on algae and a wide variety of small benthic invertebrates.

Distribution: Indo-Pacific.

Remarks: Sufflamen hursa is a common inhabitant in the Maldivian reefs. It is readily distinguished from the similar sized and shaped S. chrysopterus (next page) by colour. S. chrvsopterus is dark brown.

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Rhinecanthus rectangulus (Bloch and Schneider, 1801)

English Name: Reef triggerfish
Family: BALISTIDAE
Local Name: Gabulhi fattaa rondu
Order: Tetraodontiformes
Size: Max. 25 cm
Specimen: MRS/0346/89

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Distinctive Characters: Dorsal fin with 3 spines and 23-24 rays. Anal fin with 20-21 rays. Pectoral fin with 13-15 rays. No grooves infront of eyes. 4-5 rows of small forward curving spines posteriorly on body. Caudal fin rounded, the corners acute.

Colour: Ground colour olive brown above, pale below. Black band across body, and black triangular patch on caudal peduncle. Black areas partially outlined with green-yellow. Orange at base of pectoral.

Habitat and Biology: Common in the shallow outer reef environments exposed to surge. Diet even morevaried than R. aculeatus, feeding on a wide range of invertebrates, fishes and also algae.

Distribution: Indo-Pacific.

Remarks: Rhinecanthus rectangulus is readily distinguished from R. acu/eatus (previous page), on the basis of colour pattern. Both are found on shallow areas, but R. rectangu/us prefers more exposed locations. R. rectangu/us is a very wary fish, hence difficult to approach under water.

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Balistoides conspicillum (Bloch and Schneider, 1801)

English Name: Clown triggerfish
Family: BALISTIDAE
Local Name: Bis rondu
Order: Tetraodontiformes
Size: Max. 45 cm
Specimen: MRS/0344/89

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Distinctive Characters: Dorsal fin with 3 spines and 24-26 rays. Anal fin with 2 1-23 rays. Pectoral fin with 14 rays. A deepgroove anterior to eye. Region around lips fully scaled. 3-4 rows of spines posteriorly on side of body. Caudal fin rounded, the corners acute.

Colour: Black with very large white spots on lower half of body. Yellow markings around mouth, on face and fins. A yellow reticulum anteriorly on back.

Habitat and Biology: Usually found on outer reef terraces with surge channels. Feeds on small
benthic animals.

Distribution: Indo-Pacific.

Remarks: Balistoides conspicillum is one of the most strikingly coloured of all reef fishes. In consequence it fetches a high price in the aquarium trade.

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