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Larval rearing of the redblotch perchlet, Plectranthias winniensis

April 01, 2015

Family: Serranidae > Subfamily: Anthiinae > Genus: Plectranthias > Species: P. winniensis

 
Anthias (Anthiine serranids) are small to medium-sizedbrightly colored reef fishes, comprising 25 genera with over 200 species. They are planktivores and often form large schools (sometimes in the thousands) above the reef while feeding. Their peaceful nature, vivid color patterns and feeding habits (they do not feed on sessile invertebrates) make them ideal for reef aquariums. Most anthias species will spawn readily in captivity but are not aquacultured because the larval phase is long and complicated.

Plectranthias sp. or perchlets are bottom-oriented, secretive, mostly small fishes (less than 6 cm/2.3”) with a form and behavior more similar to hawkfishes than other anthias.  The genus comprises over 40 species, many of which are widespread throughout the Indo-Pacific. They feed on small crustaceans and usually inhabit deepwater rubble areas. Plectranthias species can make charismatic and visually stunning aquarium fishes but are difficult to collect and often command prices in excess of $1000 in the aquarium trade.

Redblotch perchlet (Plectranthias winniensis) juveniles were raised in May 2014 from pelagic eggs collected in coastal waters off Oahu’s east shore. This is a small (5 cm/2 inches) and secretive species that is rarely seen by divers. It occurs in the Indo-Pacific from the Red Sea and East Africa to the Hawaiian, Tuamoto and Pitcairn islands and south to the Great Barrier Reef and the Austral Islands. Adult specimens have been collected in 23-59 m/75-190 feet for scientific purposes.  This species is not available through the aquarium trade.

P. winniensis eggs are spherical, clear and small (0.7 mm diameter), with a single oil droplet. The larvae measure about 1.5 mm TL at hatching. They begin to feed three days after hatching (dph) (2.7 mm TL), undergo flexion near 16 dph (4.8 mm TL), and complete juvenile transition by about 80 dph (14 mm TL).  Interestingly, P. winniensis larvae look very similar to scorpionfish larvae, developing very large pectoral and pelvic fins (the former lacks parietal spines) during the preflexion stage. The larvae also develop intricate head spination, a specialization for pelagic life that is shared among all anthias.

P. winniensis larvae delay metamorphosis and have a long larval phase, which makes them more difficult to raise than other serranids. The larvae were raised together with Pseudoanthias bicolor larvae using cultured copepods and artemia as live foods. This is the first documented rearing of a Plectranthias species.