Snappers are a diverse group of medium to large (up to 3 feet), carnivorous fishes, comprising 21 genera and 125 species. They inhabit a variety of temperate to tropical habitats down to 1500 feet where they feed on crustaceans and fish. Snappers have excellent flesh quality and are fished heavily worldwide. Several snapper species are aquacultured but the larvae are difficult to rear.
Bluestripe Snapper – Lutjanus kasmira (October 2012)
The Bluestripe Snapper (Lutjanus kasmira) is one of the most widespread snapper species and occurs in a large part of the Indo-Pacific. It often forms large schools as juveniles before becoming solitary as adults. It primarily occurs on coral reefs. This species was introduced to Hawaii in the 1950’s. It has since flourished here though it failed to become a food fish due to its low market value.
L. kasmira was reared on several occasions throughout 2012 and 2013 from small batches of collected eggs. The eggs are pelagic, spherical, clear and measure 0.8 mm in diameter and have a single oil globule. Features of the larvae are an initially elongated body that quickly deepens; an early-forming, elongate second dorsal spine and pelvic spines; early-forming, visible teeth (pre-flexion) and black pigment on the dorsal fin (post-flexion stage).
L. kasmira larvae are moderately difficult to rear through flexion and require stable tank conditions and nutritious foods (copepods). Postflexion L. kasmira larvae are more robust and settle without special provisions. However, they are skittish and very capable jumpers and will commit suicide if given the chance. They also develop lordosis when provided with too much light. The L. kasmira larval period of this species is about 60 days.
Blacktail Snapper – Lutjanus fulvus (December 2012)
The blacktail Snapper (Lutjanus fulvus) was raised from wild collected eggs in 2012, 2013 and 2014. This species is widespread throughout the Indo-Pacific where it inhabits estuaries and inshore coral reefs singly or in small groups. It grows up to 40 cm. Adults feed at night on fishes, shrimps, crabs, holothurians and cephalopods. Juveniles are sometimes found in shallow mangrove swamps and the lower parts of freshwater streams. Like many snappers, this species forms spawning aggregations. Spawning is estimated from April to October in the sup-tropics and throughout the year in the tropics. L. fulvus was introduced to Hawaii with the bluestripe snapper (L. kasmira) in the 1950s. It has not displaced native species there like L. kasmira has, perhaps because Hawaii’s coastal waters have fewer suitable habitats for juveniles.
L. fulvus produces pelagic eggs that are spherical, clear, 0.75 mm in diameter and contain a single oil globule. L. fulvus larvae measure about 1.8 mm TL at hatching. They begin to feed on copepod nauplii near 3 dph (3.1 mm TL); pass through flexion between 12 and 18 dph (approx. 5 mm TL) and begin to settle near 40 dph (15 mm TL). TheL. fulvus larval phase is between 55-60 days.
Features of the larvae are an initially elongated body that quickly deepens; an early-forming, elongate second dorsal spine and pelvic spines; and early-forming and visible teeth during the pre-flexion stage. L. fulvus is the second most numerous snapper larvae reared for the project, the first being L. kasmira. The rearing and development of L. fulvus and L. kasmira is very similar.