StrikeAhead

Goldblotch grouper: the slender grouper with the golden blotch that's moving north

Among the Mediterranean groupers, it's the slender one, the pointy-snouted one, the one with the golden blotch: *Epinephelus costae* — in English the goldblotch grouper, in German Spitzkopf-Zackenbarsch (GBIF/WoRMS), at FishBase also Gestreifter Zackenbarsch or Alexanderbarsch, in Italian cernia dorata, in French mérou badèche, in Spanish falso abadejo, in Portuguese garoupa-do-Mediterrâneo, in Dutch gestreepte zaagbaars, in Finnish kultakylkimeriahven, in Russian александрийский мероу, in Turkish altın benekli lahoz, in Greek στήρα and in Croatian kirnja zlatica (GBIF, FishBase, Wikipedia). For Danish, Swedish, Norwegian, Slovenian, Albanian and Japanese we found no confirmed species name in GBIF, FishBase or Wikidata; for Arabic only regional names, such as the Libyan ثود (FishBase). Here's how to recognise it, where it lives, what it eats, why every big male was once a female — and why the sources disagree so widely on size and depth.

A grouper with two faces

It was described by the Austrian zoologist Franz Steindachner in 1878 (FishBase, Catalan Wikipedia). In the literature it also appears as *Epinephelus alexandrinus* and *Mycteroperca costae* (Italian Wikipedia) — *alexandrinus* is where the German name Alexanderbarsch and the Russian александрийский мероу come from. According to English Wikipedia, the striped juveniles look so unlike the adults that they were considered a separate species until 1882. According to FishBase it is harmless to humans.

How to recognise it

  • The shape: slimmer and more elongated than the other Mediterranean groupers, with a clearly protruding lower jaw (Italian, Greek and Catalan Wikipedia). Catalan Wikipedia calls it the narrowest of all groupers.
  • The stripes: juveniles carry 4–6 narrow dark lengthwise bands on the flanks and two oblique lines on the gill cover (Italian Wikipedia). In adults the stripes fade, but according to Greek Wikipedia they stay visible.
  • The golden blotch: adults have a golden-yellow blotch behind and above the gill cover, below the spiny part of the dorsal fin (FishBase, Italian and Greek Wikipedia). In large males, according to Italian Wikipedia, it is large and distinct, often with a dark band below it and a violet sheen on the sides of the head. Juveniles lack it.
  • The colour can change: according to English Wikipedia, an adult can make the blotch disappear and show lengthwise stripes again instead. Italian Wikipedia links the breeding livery to territorial and reproductive behaviour.
  • The eyes: according to Italian Wikipedia, a green iris at every age.
  • The fins: one continuous dorsal fin with 11 spines; the tail fin is rounded in juveniles and slightly concave in adults (FishBase, Italian and Catalan Wikipedia).

Where it lives — and why it's moving north

Its range is the eastern Atlantic and the Mediterranean; FishBase gives the bounds as 47° North to 13° South. According to Italian Wikipedia it is a more southerly species than the dusky grouper: in the Atlantic not north of Portugal, in the south as far as Angola. In the Mediterranean it was long common mainly in the south — but since the mid-2000s, according to Italian Wikipedia, it has been spreading markedly into the north as well, all the way into the Adriatic; Wikipedia calls this the meridionalisation of the Mediterranean. Croatian Wikipedia still describes it as very rare in the northern Adriatic and somewhat more common in the south.

It lives on the bottom, over sand, mud or rock (FishBase), above all on mixed sand-and-rock ground and even in lagoons (Italian Wikipedia), along the coast also in Posidonia meadows and on rocks surrounded by sand (Catalan Wikipedia). According to Greek Wikipedia, large fish live alone in a cave or crevice of their own; according to Croatian Wikipedia, usually near a boulder that gives them cover. Juveniles form small groups in shallow water (FishBase) and stay closer to shore than the adults (Italian Wikipedia); Catalan Wikipedia calls it the most sociable of all groupers. And unlike what you'd expect from a grouper, according to Italian Wikipedia it is often seen swimming freely above the bottom.

What it eats

According to English Wikipedia, its diet consists overwhelmingly of fish, plus crustaceans and cephalopods; FishBase lists crustaceans, molluscs and fish. Greek Wikipedia gets specific: cuttlefish, squid, arrow squid and small fish such as bogue (Boops boops); smaller individuals eat sand smelts, gobies and blennies, plus shrimp and, rarely, worms. Catalan Wikipedia calls it very voracious.

Female first, then male

Like many groupers, it is a protogynous hermaphrodite (Catalan Wikipedia): according to Croatian Wikipedia, all are born female, reach sexual maturity at about 30 cm and change into males at around 60 cm. Italian Wikipedia gives the same figures — females mature at 30 cm, males at 60 cm —, FishBase a mean length at maturity of 32.5 cm (30–35 cm). According to Italian Wikipedia, spawning takes place in July and August.

For you on the water, that means: the big fish are the males — and by nature there are fewer of them. If you release a large goldblotch grouper carefully, you leave the stock exactly the fish it takes longest to replace. That's not a regulation, it's our recommendation.

On the hook and on the plate

According to Italian Wikipedia it is caught with bottom trawls and longlines, according to Catalan Wikipedia also with trammel nets; it is a target of recreational fishing (Italian Wikipedia) and of spearfishing (Catalan and Croatian Wikipedia). Greek Wikipedia describes fishing from a boat with longline, handline and live bait, less often with inchiku and bottom trolling, and from the shore with heavy casting and shore jigging. It isn't easy: according to Italian Wikipedia the adults are considered very wary, and Croatian Wikipedia calls it hard to catch. According to Italian Wikipedia its flesh is excellent, if somewhat less prized than that of other groupers; FishBase places it in the highest price category and mentions a small commercial fishery.

Status — and what you can do

On the IUCN Red List it is classed as “Data Deficient”, assessed on 17 November 2016 (FishBase). According to Italian Wikipedia, neither the size of the stocks nor the fishing pressure is known; in the Mediterranean fishing is not intensive, but on the West African coast it is probably overexploited, like other groupers there. FishBase rates its vulnerability to fishing as high to very high (66 out of 100) and its resilience as medium — according to FishBase, a population needs 1.4 to 4.4 years to double.

Whether a minimum size, a closed season or a catch ban applies to it is set by national and regional regulations — there's no universally valid number, and we deliberately don't give one. Croatian Wikipedia, for example, writes that in Croatia, as for all groupers, a closed season applies in summer. Check locally what currently applies — especially in marine protected areas.

Six contradictions in the sources

  • How big does it get? FishBase and English, Greek, Croatian, Russian and Catalan Wikipedia: up to 140 cm. Italian Wikipedia only gives at least 80 cm and around 8 kg, “probably more as well”. On weight: Croatian Wikipedia just over 15 kg, Greek Wikipedia 40 kg — though it writes itself that in Greece fish of 0.2–7 kg are usually caught.
  • How deep does it live? FishBase: 1–300 m, usually 4–160 m. English Wikipedia: usually below 80 m, down to 200 m. Italian Wikipedia: 10–80 m, with reports down to 300 m of doubtful reliability. Catalan: down to about 300 m, usually 20–80 m. Greek: usually 3–70 m, but down to 1,000 m. Croatian: usually 20–80 m, down to 800 m. They all agree on the usual range — the depth records are five times apart.
  • Does it have canine teeth? Italian Wikipedia describes canine-like teeth, larger and pointed at the front. Greek Wikipedia says the opposite: unlike the dusky grouper, it has no canine teeth.
  • How far north? FishBase draws the line at 47° North — roughly the latitude of Brittany. Italian Wikipedia says that in the Atlantic it does not occur north of Portugal.
  • Does the golden blotch survive death? English Wikipedia: the yellow blotch usually disappears after death. Italian Wikipedia: the breeding livery is retained at least partly even after death.
  • Which family? FishBase and English Wikipedia place it in the Epinephelidae, Italian, Greek, Croatian, Russian and Catalan Wikipedia in the sea basses (Serranidae). That's not one side's mistake but an open question of taxonomy — the scientific species name stays the same.

Four name traps

  • Three German names, no consensus. GBIF and WoRMS list Spitzkopf-Zackenbarsch, FishBase Gestreifter Zackenbarsch and Alexanderbarsch. If you want to be sure, use *Epinephelus costae*.
  • “Abadejo” on its own is a different fish. In Spanish it's called falso abadejo — “false abadejo”. Without the “falso”, abadejo in Spain means the pollack (*Pollachius pollachius*), a cod-like fish.
  • Madeira is a mistake. Reports of *Epinephelus alexandrinus* from Madeira are, according to FishBase, apparently based on confusion with the island grouper *Mycteroperca fusca*.
  • Databases have typos. The Arabic FAO name at FishBase reads لُؤز بُقعة طهب — the last word looks like a typo for ذهب (“gold”), matching the English goldblotch. That's why we don't use it; always check names from databases against a second source.

That leaves the question every article in this series starts with: when. For a fish that hangs warily over sand-and-rock edges and only rarely takes the hook, the right day matters more than any rig. Habitat, prey and spawning season are covered above, and they're fixed. What changes every day are the conditions on your water — StrikeAhead calculates that and tells you when the trip is worth it. And because you don't know the edges and rules of an unfamiliar spot from day one, StrikeAhead Pathfinder tells you who to go out with: curated guides and skippers, personally vetted before listing — licence and insurance —, with verified catches instead of promo photos, no paid ranking and no booking fee for you as an angler. The app says when, Pathfinder with whom.