Monocentridae

Pinecone fishes
Pinecone fish, Monocentris japonica
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Beryciformes
Family:	Monocentridae
Genera
Cleidopus Monocentris See text for species.

Monocentris japonica

Pinecone fishes are small and unusual beryciform marine fish of the family Monocentridae. The family contains just four species in two genera, one of which is monotypic. Their distribution is limited to tropical and subtropical waters of the Indo-Pacific. Pinecone fishes are popular subjects of public aquaria, but are both expensive and considered a challenge for the hobbyist to maintain.

Physical description

These fish are aptly named; their rounded, compressed bodies are completely covered (with the exception of the caudal peduncle) with very large, strong platelike scales called scutes which are fortified with prominent ridges.^[1] The first dorsal fin is composed of 4-7 strong, disunited spines which vary in length; the second dorsal fin and anal fin are small, spineless and rounded, situated far back of the convex head. The pelvic fin possesses one large erectile spine which can lock into place. The pectoral fins are somewhat elongate and the caudal fin is truncate.

Coloration is typically a yellow to orange, the scales dramatically outlined in black. The eyes are relatively large, and the mouth oblique and subterminal. On either side of the lower jaw there is a bioluminescent organ called a photophore: a pale light is produced by symbiotic bacteria within the organ,^[1] and the colour of the light varies with ambient light levels—orange by day and blue-green at night.

The pineapplefish, Cleidopus gloriamaris, is the largest species, reaching up to 30 centimetres (12 in) in length.^[1] There is no apparent sexual dimorphism.

Life history

Pinecone fishes stick to the sublittoral zone, and are associated with ledges and caves, rocky and (occasionally) coral reefs over a hard bottom. Found at 10–200 metres depth (with juveniles frequenting the shallower end of this range), Pinecone fishes are nocturnal and form schools.

The photophores are thought to play a role in attracting the zooplankton upon which the fish feed; intraspecific communication may also be a use for the light.^[1] Little is known of their reproductive biology, but they are assumed not to guard their brood.

Species

• Genus Cleidopus
  • Pineapplefish, Cleidopus gloriamaris De Vis, 1882.
• Genus Monocentris
  • Monocentris japonica (Houttuyn, 1782).
  • Monocentris neozelanicus (Powell, 1938).
  • Monocentris reedi Schultz, 1956.

References

1. ^ ^{a b c d} Paxton, John R. (1998). Paxton, J.R. & Eschmeyer, W.N.. ed. Encyclopedia of Fishes. San Diego: Academic Press. pp. 161–162. ISBN 0-12-547665-5. 

• Froese, Rainer, and Daniel Pauly, eds. (2005). "Monocentridae" in FishBase. November 2005 version.