John's Snapper

Fascinating facts about the John's Snapper

• When Marcus Elieser Bloch named the fish in 1792, he honored a missionary-collector, Christoph Samuel John, whose specimens came from the Tapti River estuary where the Gulf of Khambhat meets the Arabian Sea.
• At its biggest, this snapper can reach 97 cm (38 in) long and weigh up to 10.5 kg (23 lb), but most individuals you’ll see are around 50 cm (20 in) – about the length of a standard school ruler turned sideways.
• It lives from the surface down to 80 m (262 ft 5.6 in), thriving on coral reefs as adults and hiding among mangrove roots as juveniles.
• In Australian waters the species dominates near-shore reefs, forming large schools that swirl in turbid, silty waters around hard substrates.

At a glance

About the John's Snapper

John's Snapper, Lutjanus johnii, cuts a striking figure in the Indo-Pacific seas. Its body, moderately deep and yellow-bronzed with a silvery sheen, bears a rust-colored spot at the centre of each scale, creating the illusion of horizontal lines along its flanks. A bold black blotch sits just below the front of the soft-rayed dorsal fin, though adults may lose this mark. Growing to a typical 50 cm but capable of reaching 97 cm and 10.5 kg, the fish’s dorsal fin carries 10 spines and 13-14 soft rays, while the anal fin mirrors this with 3 spines and 8 soft rays, giving it a rounded, efficient silhouette for navigating both reef crests and silty coastal waters. Its life unfolds across a vast range, from the southern Red Sea and South Africa’s coast, through the Indian Ocean, to Fiji, the Ryukyu Islands, and northern Australia, occupying depths from a whisper of 0.1 m to 80 m. Juveniles find refuge among mangrove roots, while adults patrol coral reefs and, surprisingly, form schools in turbid, hard-substrate habitats far from the reef’s bright glare. A voracious predator, it hunts smaller fish, crustaceans and cephalopods, timing its spawning in September in the Andaman Sea, a cue that hints at the subtle seasonal rhythms governing this otherwise adaptable snapper.

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