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False scad (Caranx rhonchus): the jack that looks like a scad — and feeds at midday

At the fish market it often lies among the horse mackerel, and plenty of people take it for one. But *Caranx rhonchus* belongs to a different genus: the jacks, relatives of the big trevallies. In English it is called false scad, as well as spotfin scad and yellow horse mackerel; in Italian carango ronco, in Spanish jurel real, in Portuguese charro-amarelo, in French carangue jaune or comète coussut, in Dutch valse horsmakreel, in Turkish kral balığı (GBIF, English and Italian Wikipedia). In German, GBIF lists it as Gestreifter Stöcker (“striped scad”). Here is how to recognise it, where it lives, what it eats — and why it is a particularly good fit for the question of when.

Name and origin: the “snorter” from Alexandria

It was described by the French naturalist Étienne Geoffroy Saint-Hilaire in 1817, from a specimen from Alexandria in Egypt. The species name *rhonchus* is Latin and means roughly snorting or croaking — after the sound the fish often makes when it is pulled out of the water (English Wikipedia). Its home is the eastern Atlantic: from Morocco to Angola, occasionally as far as Namibia, plus the Mediterranean (FishBase). It matters most commercially between Morocco and Senegal (English Wikipedia).

How to recognise it

  • Slim like a scad, not deep-bodied like a trevally. The body is elongated and only slightly compressed; body depth goes 3.8 to 4.4 times into fork length (FishBase). This shape alone sets it apart from the other *Caranx* species — whereas telling it from the true horse mackerels (*Trachurus*) and mackerel scads (*Decapterus*) takes a closer look (English Wikipedia).
  • A small extra finlet at the back. The last ray of the second dorsal fin and of the anal fin is modified into a partly detached finlet, joined to the preceding ray only by a low membrane (FishBase, English Wikipedia). This is the best field mark for telling it from the true horse mackerel.
  • Black spot at the top of the second dorsal fin, at the tip of the front lobe, often with a pale margin above it — hence the English name *spotfin scad*. Another black spot sits on the gill cover, sometimes only faintly visible (English and Italian Wikipedia).
  • Yellow tail, yellow stripe. Bluish-green to olive-brown above, silvery white below, often with a narrow yellow to golden stripe along the flanks from head to tail base. The tail fin is yellow, the other fins translucent to dusky (English Wikipedia).
  • Lateral line with bony shields. Slightly curved at the front, straight at the rear; the straight part carries enlarged scales, the scutes (English and Italian Wikipedia). A well-developed adipose eyelid covers the rear of the eye (FishBase).
  • Size: up to 60 cm and 1 kg, typically around 35 cm (FishBase, English and Italian Wikipedia).

Where it lives in the Mediterranean

Unlike the barracudas from the Red Sea, *C. rhonchus* is not an immigrant through the Suez Canal — it is native to the Mediterranean; its type specimen comes from Alexandria and was described in 1817, decades before the canal opened in 1869. How widely it is distributed in the Mediterranean, however, is something the sources describe very differently (see below). It swims in schools, often mixed with other semi-pelagic fish, mostly close to the bottom over sand or mud, but at times also at the surface; FishBase gives 30–200 m, mostly 30–50 m. Juveniles stay in shallow coastal water, including lagoons and estuaries (FishBase, English Wikipedia). Like other jacks, it readily gathers around drifting fish aggregating devices (buoys, FADs) (English Wikipedia).

What it eats — and when

  • A predator that switches as it grows. A study off Cap Blanc found that fish of 23–30 cm ate mainly lancelets (*Branchiostoma lanceolatum*), those of 30–35 cm krill and mysid shrimps, and those of 35–55 cm mainly small fish (English Wikipedia). The bigger it gets, the more fish it eats.
  • The season shifts the prey. In autumn and winter crustaceans dominate, in summer it eats small fish more often; in winter it eats the least overall (English Wikipedia).
  • A day hunter, not a night hunter. According to the study cited in English Wikipedia, it feeds mainly around midday — and not at all at night. For a predator from the jack family, that is a remarkably clear statement; it does, however, come from research off West Africa, not from the Mediterranean.
  • Spawning in summer, in shallow water. Sexually mature in its second year at about 20 cm; it spawns in batches in shallow coastal water, and the eggs drift in open water (FishBase, English Wikipedia). A female of 29–35 cm releases 480,000 to 990,000 eggs (English Wikipedia).
  • Conservation status: not threatened on the IUCN Red List (Least Concern, assessed 2013). FishBase rates its resilience to fishing as medium (doubling time 1.4–4.4 years) and its vulnerability as medium (36 out of 100).

Where the sources disagree

  • How far into the Mediterranean does it reach? FishBase: only along the African coast. English Wikipedia: most of the Mediterranean, east to Turkey, Egypt and Israel, north to Italy, Greece and Albania. Italian Wikipedia: mainly in the south and east; only since 2019 also in the central Mediterranean and in Italian waters, where it was previously “very rare”.
  • How deep? FishBase: 30–200 m, mostly 30–50 m. English Wikipedia: 15–200 m. Italian Wikipedia: mostly 30–50 m, sometimes down to 200 m or at the surface.
  • When does it spawn? English Wikipedia: in the Mediterranean June to August, off Senegal April to November — yet the introduction of the same article says April to July. Italian Wikipedia: May to September, peaking in July.
  • Short or long pectoral fins? FishBase: short (1.0 to 1.2 times in head length). Italian Wikipedia: sickle-shaped, reaching the start of the second dorsal fin.
  • How many rays and scutes? Second dorsal fin: 28–32 soft rays (FishBase, English Wikipedia) or 26–31 (Italian Wikipedia); anal fin 25–28 or 23–27; scutes in the straight part of the lateral line 24–32 (English Wikipedia) or 22–28 (Italian Wikipedia). FishBase also counts 9 dorsal spines, the others 8 + 1 — that is the same count, just written differently.
  • How much is caught? English Wikipedia, introduction: 500 to 19,000 tonnes a year. The same article further down: 1,500 to 3,700 tonnes (FAO, 2002–2007), 4,000 to 19,000 tonnes in the years 1979–1992. So the range mixes old and new figures.
  • Is it even a *Caranx*? Going by its anatomy, yes — that is how FishBase and most authorities list it. But it was at times placed in *Decapterus*, and a genetic study found it closer to *Decapterus* and *Trachurus* than to *Caranx*; another study recommended a genus of its own, which has not been erected so far (English Wikipedia).

Three name traps

  • “Scad” is just a name here. The true scad, or horse mackerel, is *Trachurus*. According to English Wikipedia, traders even deliberately sell *C. rhonchus* as “horse mackerel” — and catch statistics often don’t separate it from *Trachurus*, which is why the official figures are probably too low. GBIF, too, lists the French names “chinchard” and “saurel” for it — both names of the true horse mackerel.
  • Spanish names under “German”. Among the German names, GBIF also lists “Jurel Real” and “Mascarela Real” — these are Spanish trade names, not German ones. And under English it lists “Pollock”, a name that actually belongs to the cod family.
  • Caranx angolensis is not a separate fish: in 1919 Henry Weed Fowler described it again under this name; it was later recognised as the same species (English Wikipedia).

Which brings us to the when, where every article in this series ends. For hardly any other fish is the evidence on this so explicit: it feeds by day, most heavily around midday, and least in winter — at least where it has been studied. Habitat, prey and features are covered above, and they don’t change. What changes every day are the conditions on your water — StrikeAhead calculates them and tells you when the trip is worth it. And because nobody knows the edges and rules of unfamiliar water 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 shots, no paid ranking and, for you as an angler, no booking fee. The app tells you when, Pathfinder who with.