StrikeAhead

Cobia fishing: the fish that looks like a shark — and swims after sharks

Anyone who sees a cobia underwater for the first time often takes it for something else. It carries its large pectoral fins spread out horizontally, and according to the English Wikipedia this may give it the profile of a shark; the Russian and Japanese Wikipedias write that divers can mistake it for a small shark. On top of that, it swims after sharks, sea turtles and mantas. This article is about the cobia, *Rachycentron canadum* — in German Cobia, Kobia, Königsfisch or Offiziersbarsch, in Brazilian Portuguese beijupirá, in Finnish okamakrilli, in Dutch batjauwvis, in Japanese スギ (sugi).

A loner with an escort

The cobia is a fish without close relatives: according to FishBase and almost all the Wikipedias it is the only species of its genus and of its family, the Rachycentridae. Its closest kin, according to the German Wikipedia, are the remoras and the dolphinfishes, to which this series devotes a group of its own. With the remoras it shares a habit, according to the English Wikipedia: it follows larger animals — sharks, turtles, manta rays — and eats whatever falls its way. The Finnish Wikipedia writes that it is often found near devil rays, and that nobody knows why.

According to FishBase it lives over mud, sand and gravel, over coral reefs, off rocky shores and in mangroves; inshore around pilings and buoys, offshore around drifting and stationary objects, occasionally in estuaries. According to the English Wikipedia it gathers at reefs, wrecks, harbours, buoys and other structures, and it hunts as far as estuaries and mangroves. According to the English Wikipedia it tolerates salinities from 5 to 44.5 parts per thousand — from brackish water to water saltier than the open ocean.

On what it eats, the sources largely agree: crabs, squid and fish (FishBase, the English, French and Dutch Wikipedias). The Italian adds bivalves and octopus, the Russian gives a stingray as an example. According to the English Wikipedia it is very curious and shows little fear of boats; the Russian adds that it sometimes follows hooked fish right up to the side of the boat. Its English nicknames crabeater and prodigal son appear in GBIF and in the English Wikipedia.

How to recognise it

An elongated, spindle-shaped fish with a broad, flattened head (FishBase, the English, German and Russian Wikipedias). The eyes are small, the lower jaw projects slightly (English, Russian, Japanese Wikipedias). The surest feature sits on its back: in front of the long dorsal fin stand short, stout, sharp spines, separate and not connected by a membrane — FishBase gives 7 to 9, usually 8. Hence the family name: Greek *rhachis*, spine, and *kentron*, sting. In adults the tail fin is lunate to slightly emarginate, with the upper lobe longer. It has no swim bladder (English, Russian, Japanese Wikipedias).

According to the English Wikipedia it resembles the remoras, but has no sucking disc and a stouter body; the Japanese adds that its tail fin is forked. The colour: back and flanks dark brown, with light and dark lengthwise bands along the side — though how many there are, and what colour, the sources tell differently (see below). According to the English and Russian Wikipedias the stripes stand out clearly in the spawning season. Young cobia, according to the English Wikipedia, are conspicuously banded black and white.

  • Size: FishBase gives 200 cm total length as the maximum, 110 cm as the common length and 68 kg as the heaviest published weight. According to the English Wikipedia the record certified by the IGFA weighed 79.6 kg, caught near Rottnest Island (Australia).
  • Age and maturity: FishBase gives 15 years as the maximum reported age. Males mature at two, females at three years according to the English Wikipedia; according to the French Wikipedia at 60 to 65 cm (males) and 80 cm (females).
  • Spawning: According to the English Wikipedia by day, from April to September, in large aggregations offshore; a female can spawn up to 30 times in one season. The eggs measure 1.2 mm and drift in the plankton.

Where it lives — and what the Mediterranean has to do with it

FishBase: worldwide in tropical and subtropical waters, between 47° North and 37° South — in the western Atlantic from Canada and Massachusetts to Argentina, including the Gulf of Mexico and the entire Caribbean; in the eastern Atlantic from Morocco to South Africa; in the Indo-Pacific from East Africa and Hokkaido to Australia. According to the English Wikipedia it migrates with the seasons: it spends the winter in the Gulf of Mexico, passes Florida heading north in March, and in summer reaches Massachusetts — the Russian and Japanese Wikipedias say: Maryland.

And the Mediterranean? FishBase does not list it in its distribution. The Norwegian Wikipedia writes that it does not occur there naturally, but that there have been two records of fish that probably came through the Suez Canal; as its source it cites a scientific paper from 2013 on the second record in the Mediterranean. The English Wikipedia speaks of reports from various locations in the eastern Mediterranean since 1978, arriving either via the Suez Canal or as escapees from fish farms. The Italian counts only one record, in Israel in 1986, and does not rule out an origin in the Atlantic. The Hebrew writes that a fisherman caught the first one in the Mediterranean in 1978.

For anglers in the Mediterranean this means: there, a cobia is not a target fish but a rarity — by every source a handful of fish in decades, all in the east. Anyone who wants to fish for cobia on purpose has to go to the Atlantic, the Caribbean or the Indo-Pacific. How it is caught there, FishBase describes briefly: mainly with handlines and by trolling over the continental shelf; it is also a gamefish. According to the Spanish Wikipedia it is above all the large specimens that sport anglers prize.

Careful on board — and on the plate

Two sources carry a warning: according to the Russian Wikipedia it keeps its pectoral fins horizontal even after it is caught, which lets it stay upright, and its vigorous resistance makes it dangerous on board; the Japanese Wikipedia advises caution after landing it. On the plate it counts as an excellent food fish (FishBase, German Wikipedia): according to the English Wikipedia its firm flesh commands a relatively high price. But because it lives alone, according to FishBase it is caught only in small quantities — instead, it is a big subject in aquaculture. According to the English Wikipedia, in 2004 80.6 % of world production came from China and Taiwan; in Taiwan around 80 % of marine cages are used for cobia farming.

Eight contradictions, left standing

  • How often has it been in the Mediterranean? The Italian Wikipedia: once, in Israel in 1986. The Norwegian: two records. The English: at various locations in the east since 1978. The Hebrew: the first in 1978. FishBase does not list the Mediterranean in its distribution.
  • Does it live in the eastern Pacific? FishBase and the Spanish, Dutch and Swedish Wikipedias: no, it is absent there; the Norwegian: it is absent from the central and eastern Pacific. The English Wikipedia: juveniles that escaped from an aquaculture farm off Ecuador in 2015 have established it there; it spread to Colombia and Panama.
  • How heavy does it get? FishBase and the Spanish, French, Dutch, Norwegian, Japanese and Russian Wikipedias: 68 kg. The German, Italian and Swedish: 70 kg. The Hebrew and Arabic: 78 kg. The English: 79 kg. And the angling record: the English Wikipedia gives 79.6 kg as the certified record and 60 kg from Shark Bay as the previous best; the Russian gives 46.4 kg as the entry in the official record list.
  • How much cold can it take? FishBase: 17 to 32 °C. The English, Japanese, Russian and Arabic Wikipedias: 1.6 to 32.2 °C. The Hebrew Wikipedia adds that, unlike most fish, it can regulate its body temperature; the English only calls it tolerant of a wide range of temperatures.
  • How many stripes, and what colour? The English, Japanese, Russian and Arabic Wikipedias: two dark lengthwise bands. FishBase and the Spanish: two narrow silvery bands. The German: three dark brown stripes, separated by narrow silvery bands. The Finnish: two or three silver-grey. The Hebrew: three dark and two white. And the belly: yellowish according to FishBase, white according to the English Wikipedia.
  • Loner or group? The English, French and Arabic Wikipedias: a loner, except at spawning time. FishBase and the German, Finnish and Swedish: it forms small groups. The Russian says both: it lives mostly alone, but large groups are often seen at reefs and wrecks.
  • What does the juvenile look like? The English and Arabic Wikipedias and FishBase: young cobia have a rounded tail fin. The Japanese: their tail is already forked like the adults’, and they carry clear white lengthwise stripes.
  • What eats it? The English, Russian, Japanese and Arabic Wikipedias: dolphinfish eat the juveniles; adult cobia are taken by the shortfin mako (according to the Russian and Japanese Wikipedias, from fishermen’s reports). The Italian: the adults are prey of dolphinfish.

Five names that lead to the wrong fish

  • “Ling”. The English Wikipedia and GBIF also list the cobia as ling. But in English that is also the name of the common ling (*Molva molva*), a North Atlantic relative of the cod, to which this series devotes a group of its own.
  • “Bacalao”, “bacalhau”, “cod”. GBIF also lists it in Spanish as bacalao, in Portuguese as bacalhau, in English as cod; the Spanish Wikipedia also gives bacalao. All three words otherwise stand for the Atlantic cod, to which this series also devotes a group of its own.
  • “Bonito negro”. The Spanish Wikipedia also calls it bonito negro, GBIF in Spanish simply bonito, the English Wikipedia black bonito. But a bonito in the usual sense is a small tuna (*Sarda sarda*), to which this series devotes a group of its own.
  • “Kingfish” and “Königsfisch”. The German Wikipedia gives Königsfisch, GBIF and the English Wikipedia kingfish and black kingfish. But depending on the region, the English kingfish also stands for quite different fish, such as amberjacks.
  • “クロカンパチ”. In Japan, according to the Japanese Wikipedia, the Fisheries Agency has ruled that cobia must not be sold as クロカンパチ (kuro-kanpachi) or トロカンパチ (toro-kanpachi) — because カンパチ is the greater amberjack, a premium fish to which it is not related; the names were not to mislead buyers. This series devotes a group of its own to the greater amberjack.

That leaves the question every article in this series starts with: when. Habitat, prey and habits are above, and they are fixed. What changes every day is everything else — and whether a day on the water is worth it is decided right there. That is what StrikeAhead works out: it takes the conditions on your water and tells you when the trip is worth it. And because nobody reads wrecks, buoys and the mantas’ escorts from day one, StrikeAhead Pathfinder tells you who to go out with: curated guides and skippers, personally checked before listing — licence and insurance —, with verified catches instead of promo photos, no paid ranking, and for you as an angler no booking fee.

Fish the right moment →