Today we have to talk about a somewhat exotic fish. Its about san pedro fish. It is also known by the common name of San Martín fish and its scientific name is Zeus faber. It belongs to the group of teleosts and is considered a delicacy in gastronomy, although, as not much is known about the species, it is not as widely consumed in the world.
In addition, this fish accumulates a rich tradition of local names: Sanmartiño, San Martín, Gallopedro, Gall of Sant Pere, gall marí, Muxu Martin, Oiarra o Martina, among others. According to legend, The dark stain on its flanks would be the fingerprints of the apostle after extracting a coin from its mouth to pay a tribute, a popular story that has fueled its reputation as a “legendary fish.”
Let's go learn more about the John Dory!
Key features
This fish has the body quite compressed laterally and oval. The color is olive-yellow as if it were soaked in oil. You can notice a irregular line pattern in golden-yellow tones from head to tail with a large dark rounded spot on its sides, often edged with white or yellow. The lateral line It is visible and shaped like a light S, being the only place where they appear small scales on an otherwise very thin skin.
The head is larger than normal and has bony ridgesAlthough the head is large and its eyes are also large, its protractile mouth It can project forward to suck in prey and is equipped with small teeth. The dorsal fin is very elongated, with between 9 and 11 spiny rays, and the anal fin presents 4 spiny rays; the caudal fin is small, formed by soft rays, and the pelvic fins are somewhat elongated.
They are fish that when they reach sexual maturity develop longer filaments on the rear of the dorsal fin. This is often used as an indicator for researchers trying to study the species and determine its stage. It has small scales, although in some species they are not noticeable; in the case of the Saint Peter's, they are located mainly on the lateral line.
The eyes are bright yellow with the nostrils very close and close together. It is normal for Their life expectancy is around 12 years and that it reaches in this time usual lengths of 30-40 cm, although it can reach large sizes close to 65-70 cm and around 5 kg weight in exceptional specimens. It has a rather solitary behavior, although it can sometimes be seen forming small groups up to 6 or 7 specimens, something more common during the mating season or when they are associated with schools of sardines or herring.
The main characteristic that makes this fish stand out is its rather unattractive appearance. Not because it's ugly, but because of this appearance, could go unnoticed for a long time Since fishermen and consumers didn't bother trying to catch it, it was more common to catch other fish such as hake, snapper, and sardines. However, over time, many diners have tried its exquisite flesh and have praised the John Dory as one of the most delicious delicacies. Its meat is tender, fine and white and when eaten it softens the palate a lot, with a texture similar to turbot or sole.
Range and habitat
These fish can be found from coastal areas to mid-depths. Ecologically, they are considered coastal benthopelagic fish, that is, they move near the bottom but also in the water column. They are most commonly found between 10 and 50 m, although they are frequent until 200 m and have been registered appearances from 5 to 360-400 m deep. It usually hunts its prey unseen, as it buries itself in the sand at the bottom of the sea and then rises to the surface or advances very slowly with undulations of its fins to surprise its prey.
Its distribution area covers the eastern Atlantic (from cold latitudes of northern Europe to temperate waters of southern Africa), the Mediterranean and the Black Sea, and regions of the Indian and Pacific Oceans. It is also found in waters of Australia, Japan and New Zealand, where it is more common in areas with temperate waters.
We can easily find this fish in Spain from one end of the peninsula to the other. If we want to eat this fish, we may be confused because it receives different names depending on the areaFor example, in the Basque Country it is known as Muxu MartinIn this area it is well known and consumed for being a tasty fish, and also responds to names such as Sanmartiño, Gallopedro o cock according to local tradition.
As for habitat, the Young fish often occupy rocky bottoms and seagrass meadows such as posidonia, where they find shelter and food, while adults They prefer sandy or mixed bottoms where its camouflage is more effective for hunting.
San Pedro fish diet
Although this fish may not look too scary, It is located at the top of the food chain, along with other predators. Most commonly, their diet is based on other fish of different species and in the youth stage. Among his favorite menu items are sardines, anchovies and herring (family Clupeidae), as well as small gadoids such as pouts. If these fish cannot find their preferred food, they may resort to other foods such as cephalopods (cuttlefish and squid), crustaceans like shrimp and sometimes marine worms.
In order to hunt its prey it uses two main techniques. First, the ambush: it buries itself in the seabed to go unnoticed and surprise its prey. When it buries itself, it leaves only its crest or dorsal spines as a visual “hook” for another fish to bite; that's when projects its mouth like a tube and sucks in the prey with a powerful snap.
Another technique is slow stalking: approaches very slowly and, when it is at the optimal distance, pounces and swallows its target with its protractile mouth. Thanks to its extremely thin body seen from the front, it is not a fast fish, but it is very precise in maneuvers, allowing him to approach without raising suspicion.
The structure of your mouth and the premaxillary bone They promote effective suction and then the water is expelled through the gills. large eyes in a high position provide good depth perception for calculating attack distance. The side stain can also play a role in visual deception against prey and potential competitors.
Reproduction
These fish take a long time to reach adulthood and be able to reproduce. It is normal for them to take 3 and 4 years between in being able to have their own offspring. Another indicator of their maturity is their length. They should be between 29 and 35 cm to know that they are ready for reproduction, with estimates that in some populations place the size around 35-40 cm, reflecting regional variations.
They reproduce oviparously. The female release the eggs into the water, which are subsequently fertilized by the male when he releases sperm. The area where they usually reproduce and spawn is in relatively shallow waters, around 100 meters. According to observations in different areas, Eggs and larvae may remain associated with the bottom during their early development, moving into more open waters as they gain swimming ability.
The reproduction process usually occurs in the warm months, when food is abundant. Depending on the water temperature, the fertilization process may be faster; in warmer waters, Reproductive activity can be observed from spring. The young specimens travel long distances until they find the ideal place to lay their eggs; on the other hand, the older ones They remain loyal to certain areas to perform the laying.
Once they have laid their eggs, significantly increase their feeding activity, which also explains the seasonality of spawning. In nature, their main predators They include bottom-dwelling sharks such as the sand shark and large bony fish, so maintaining camouflage strategies and hunting efficiency is key to their success.
Nutritional value and gastronomic qualities
The John Dory is a fish semi-fatty white meat, highly appreciated for its firm and delicate texture and Smooth flavor. In nutritional terms, it offers proteins of high biological value and a fat content moderate-low, with energy values that can be placed around 75-95 kcal per 100 g depending on the piece and the cut.
Contribute Group B vitamins (especially B3, B6, B9 and B12) and minerals such as phosphorus, magnesium, potassium, sodium and iodine. For its content of sodium and cholesterol (approx. 150 mg/100 g of meat in some tables), It is advisable to moderate its consumption in specific diets for hypertension or dyslipidemia, always following professional guidelines. In general, it is a fish suitable for balanced diets and highly valued by athletes and families.
From the organoleptic point of view, its white and smooth meat reminiscent of turbot or sole. edible portion is around 50% of the weight after removing the head, fins and bones, so about 200 g of clean meat per diner is a useful reference; consequently, a piece of about 1 kg is usually adequate for two peopleThe spines are concentrated in the abdominal area and, although it lacks visible scales, It does have scales on the lateral line, which makes it easier to prepare.
How to choose and cook it
To buy a San Pedro at its best, look at its shiny greenish-grey or olive-coloured skin, intact ridges, bright eyes and gills or with a soft smell of the seaAsk at the fishmonger for cuts to your liking (loins, slices or gutted) and remember that freshness is key to perceiving that sweet nuance that characterizes it.
In the kitchen, it works perfectly with simple preparations that respect their flavor: grilled with olive oil and lemon, baked with baker's potatoes, Galician style, steamed or in paper to retain juices and nutrients. Breading fillets is a kid-friendly option, and its scrap and thorns are excellent for broths or fumets. Keep in mind the doneness: being a firm and fine meat, It is preferable not to overcook to prevent it from drying out.
Fishing gear and sustainability
The San Pedro is caught with different fishing gear. The traditional arts such as trammel’s most emblematic landmarks, the longline and line fishing are associated with higher quality specimens due to the selectivity and handling of the fish. It can also appear in catches of trawl netsIf you are interested in sustainability, ask about the the origin, Size and arts employed, and follow local recommendations minimum sizes and capture seasons.
In fisheries management, its first maturity size It is usually located between 29 and 40 cm according to populations. Checking the current regulations in your area helps promote a responsible consumption. On a global scale, the status of their populations can vary by area, with assessments historically indicating insufficient information in certain areas, so traceability and informed purchasing are important.
The John Dory fish, or Zeus faber, sums up like few others the balance between surprising biology, highly efficient hunting adaptations or with a outstanding gastronomic valueUnderstanding their distinctive features, diet, and habitat, along with good purchasing and cooking practices, allows you to fully enjoy fish of exceptional quality while promoting a more respectful relationship with the marine environment.