Goldblotch grouper (Epinephelus costae) — spearfishing in Morocco

01 Telling it apart

A grouper with a grouper’s big head and mouth, but slimmer and more elongated than the dusky, grey-brown to pale brown with faint darker oblique lines along the flank and a paler belly. Juveniles and young adults carry a distinct golden-yellow blotch on the flank behind the pectoral, which fades on old fish. The tail is rounded and dark-edged, the dorsal long.

At distance it is a pale, elongated grouper hanging in midwater a metre or two off the rock, or moving slowly along a wall, rather than sitting in a hole. Where a dusky sits and looks, a goldblotch drifts and turns.

Big old fish are plain grey-brown and are told from a dusky by the slimmer body and the faint oblique lines.

02 Habitat

Rocky coasts from a few metres down, with a preference for deeper walls, boulder slopes and the edges of reefs where they meet sand. It uses holes and overhangs for shelter but spends more of its time in the open than the dusky, patrolling a stretch of rock in midwater.

It hunts fish, cephalopods and crustaceans, often in small groups of two or three, and it follows a diver at a distance out of curiosity.

Juveniles live in shallower rock and move deeper with age.

03 Where to find it in Morocco

Both seaboards, and common on the Atlantic rock from Tangier to the Sahara, where it far outnumbers the dusky. Present on the Mediterranean rock too.

The IUCN could not assess its status for lack of data, and there is no Moroccan study. The maturity and sex-change figures are from Tunisia and the Adriatic.

04 Spawning

Summer, from around June to August, on the rock where it lives. Female first: fish turn male at around 60 to 70 cm, so the large individuals are the males, as with the dusky.

Growth is slow after the first years and a large goldblotch is old.

05 Behaviour

Curious and more mobile than the dusky. It comes out to a diver, holds off at a few metres, and follows him along the rock; it is warier than the dusky but far less than a seabream, and a still diver is often approached.

It does not sit tight in a hole under pressure. It moves off along the wall and comes back later.

Groups of two or three are common, and where one is seen the others are close.

How you approach it

A still wait on a deep wall or boulder slope, at the edge of the rock. It comes out to look, holds off, and closes on a diver who does not move.
Let it make the approach. It follows and circles; the shot is on the second or third pass, not the first sighting.
A 90 to 110 cm gun with a solid shaft. The fish is thick through the head and a light shot does not hold.
Aim at the head or the shoulder. A hit further back lets it reach a hole, and a grouper in a hole does not come out.
Take a mid-sized fish, not the largest of a group. The largest is the male.

What people get wrong

01 That it is a young dusky grouper. The body is slimmer, the flank carries oblique lines and a gold blotch, and it hangs in midwater rather than in a hole.
02 That Data Deficient means safe. It means no one has counted; the same biology that emptied the dusky applies here.
03 That a grouper that follows you is easy. It follows at a distance and closes only on a diver who has stopped.

Do not confuse it with

The species this one is taken for, and what tells them apart.

Dusky grouper, Epinephelus marginatus — heavier, darker, mottled with pale blotches, and it sits at a hole rather than drifting off the rock.
Comb grouper, Mycteroperca rubra — more elongated still, reddish with fine pale spots, a lunate tail, in open water over deep rock.
White grouper, Epinephelus aeneus — greyer with three or four pale oblique lines on the head; more a fish of sand and mud bottoms.