FISH SPECIES - A BRIEF INTRODUCTION
FLATFISH
Flatfish are living at the bottom of the sea and they don't move much, as they eat organisms that also live at the sea bottoms. Their flesh is mild, tasty, and it can be kept well for several days, since they are not high on degrading enzymes (due to their lower energy needs). The family of flatfish includes soles, halibuts, turbots, flounders, or plaices.
The characteristic of flatfish is that both eyes are placed on one side of the head, something that is actually achieved during growth and maturation of the fish (one eye from the bottom side "walks over" to the upper side). Some fishes are able to extend their eyes forward, which is important if one sits on the bottom of the ocean. Also, their dorsal (back) fin is extended onto their head. Taken together, flatfish may look grotesque, especially when one looks at their head, although they taste fenomenally good!
The most appreciated flatfish is probably Dover sole (Solea solea, or as it sometimes is called: Solea vulgaris). Its upper side is brown with yellow-brown spots, and the bottom side is white. The chest fins are small, and the upper chest fin has a black spot. The mouth is placed on the right side, and it has some "beard hairs" sticking out on the bottom side - a common characteristic of soles. It feeds on small animals, like worms, small mussels, small fish. Dover sole starts its life as a plankton and migrates to the bottom when it reaches 8 weeks of age. It is normally over 10 inches/30 cm long, but it can be twice as big when it lives long enough. Its flesh is tasty and succulent, and it is said to be best about two days after the harvest. They can be eaten all year round.
Turbot (pronounced turbit, not turbo!) is another flatfish, and a more prominent hunter. Its size is twice the Dover sole, and its flesh is slightly firmer and sweet. It is a popular aquaculture fish, as it is farmed in Norway, France, and even in China. The color of the skin is grey-brown-black, and the bottom side is white. Its chest fins are quite big, as compared to soles. They are best at autumn and winter, as they mate during april-august. The best part of turbot is said to be the meat nearest the fins.
Halibut (Hippoglossus hippoglossus), a very popular fish, is a great hunter, and it can be very big - about 10 ft/3 m. It eats squids and shrimps, as well as other fish. So, even if it spends most of the time at the bottom of the sea, it moves up the water column for food. Due to its size and predatory nature, it is almost at the top of the food chain (it is eaten by orca whales or salmon sharks). It is mating from december to may, and it takes about 8 years or more for halibut to become ready for this. Interestingly, all halibuts start their lives as males, and become females when they reach a certain body size. Its skin is brownish with grey spots, although it seldom sold as a whole fish (due to its big size). It has a big mouth and is maybe the only flatfish with a concave anal fin. Halibut meat is white, firm and lean. For those who are not aware - California halibut is really a flounder. Authentic halibut is either Atlantic or Pacific, or you can also try a more fatter version, the Greenland halibut.
Flounders are typically around 10 in/25 cm, although they can grow to a size of a few feet. As the other flatfish we described, flounders are hunters, they dig into the sea bottom mud and try to ambush small fish or crustaceans. Flounders are considered to be best in spring or autumn.
Plaice is another flatfish, with characteristic red or orange dots on the upper side. It also has small bones, arched and bulging out behind the eyes. The bottom side is white. The usual weight of a plaice is 0,3-0,6 kg. Notice that there are different kinds of plaice: European, American, and Alaska plaice.
ROUND FISH
Round fish are so many and they taste so differently, it is up to each one of us to try out the big culinary varieties they offer. Here, we will go through some of the most popular roundfish available.
Herring
Within the herring family we can find anchovy, sardine, sprat, and shad. They are colored silver and have just one dorsal fin. Their lower jaw is extended and they lack the otherwise fish-typical lateral line. In size, they vary greatly depending on where they are caught, but they are usually not bigger than 16 in/40 cm and less than 1.5 lb/700 g. In most cases they are much smaller than that. Herrings live on the small seafood, like zooplankton, which is filtered from the water that passes through their gills. For this, they need to be very active, so their flesh contains lots of enzymes that develop the strong flavors shortly after herrings have been caught. This is what anchovy is so famous for! Herrings have a good amount of omega-3 fatty acids, they can be used in a variety of cooking techniques, and they can be fermented or even eaten raw. They can even be smoked: a smoked herring is called kipper, bloater, or buckling, depending on how it is prepared prior to smoking (they can be split, whole, or have their guts removed, respectively). The guts can provide additional flavor if they remain inside the fish. Herrings are generally good all-year-round, with some exceptions (see below).
Anchovy is a small fish, with a strong characteristic flavor, used in Caesar salad dressing (although not in the original Caesar salad!). This flavor however, develops during the curing process, and fresh anchovies are much milder. They spawn between october and march, and are caught extensively in the Mediterranean and along the Atlantic coast of Europe. Anchovies are eaten by many predators, so they can be used as a bait for the bigger fish, e.g. sea bass!
Sardine, as the name implies, is caught mostly outside the coast of Sardinia in the Mediterranean. Actually, there are many sardine species, and it is common that the sardines you find in the supermarket are sprats or other herrings. The best sardines are split, with their guts removed, and their heads cut off. They are often prepared in the popular "herring style" - canned in oil or other natural preservative. It is worth mentioning that anchovies and sardines, if too old, can cause scombroid food poisoning that must be treated by a physician.
Sprat is known for the sharp, saw-looking scales that form a typical pattern along the belly. The best season for sprat is usually during the cold winters, since it is mating during the warmer seasons.
Shads are spawning in the rivers, they have a nice mild flavor, and are quite bony, but still - they are definitely worth trying. In a traditional manner, a shad is prepared with a small splash of vinegar, although their flavor is so sufficient per se that they hardly need any other aromatic ingredient over them.
Tuna, mackerel, swordfish
Tuna is a big predator, and it can weigh as much as 700 kg! Its muscle is filled with oxygen-storing myoglobin, which gives it the dark red color, and assures that it can constantly swim at high speeds. The oxygen in the muscles is used to burn both fat and protein, in other words - it is much like our own muscle. Tuna actually reminds somewhat of beef when it comes to flavor, and this is partly because of a similar physiological chemistry. Of certain value is the tuna belly where more fat is stored. Especially the tunas that live in the deeper waters and therefore store more fat (e.g. bluefin tuna or bigeye tuna) are very appreciated for their smooth belly meat. The bluefin tuna is the one that lives longest and can be very, very big. Bluefin tunas can raise their body temperature with pure muscle activity, which is the reason they can live in deep waters. On the other hand, it is a rare catch - usually, what we get on our tables are the yellowfin or albacore (light-colored) tunas, as well as skipjack tuna. They are not that big and their fat content is lower. These tunas are abundant, they mate frequently and quickly, and they are the leading source of tuna meat for us.
Mackerels are the smaller cousins of tunas, and they are rich in the tasty amino acids and other nice flavors. A typical mackerel is below 1 kg, and it is a predator with red muscles. (Some mackerels, like king mackerel can be quite big, up to 160 cm.) Mackerel is best from spring to autumn. It should be prepared as soon as possible after the harvest, as its meat is sensitive to a prolonged storage. Older meat can cause scombroid food poisoning, due to chemicals that are too stable to be cooked away. In other words, eat your mackerels fresh! If you still happen to get poisoned (bad stomach, nausea, flushes, etc.) then you should get some anti-histamines from your doctor.
Swordfish can be very large and can weigh half a ton. They are predatory fish, with the characteristic projection from the upper part of the mouth, as well as very firm, meaty flesh that keeps well on ice for many days. People usually wonder if the "sword" is really used as a weapon. It is! Although swordfish doesn't have many potential predators, but it has been reported that a swordfish has rammed into a shark, driving its sword into the enemy's belly or gills.
Bass
The nice sea basses, with tremendous flavor and firm meat, are usually divided into three classes: European sea bass, black sea bass, and striped bass. They have become a part of the all-growing aquaculture, just because they are so popular on a dinner table. Black sea bass is...black, although they can adjust their skin color to the surroundings (gray, deep blue). The characteristic vertical bands running along their skin, and the net structure-like pattern on the skin are striking for black sea bass. They live near the bottom of the sea, often close to rocks or piers, and they are predatory fish, so they eat crabs, lobster, and small fish. A common weight for a black sea bass is below 2 lb/1 kg. The European sea bass is another fish worth trying, it can be about 1 m long, and it's a popular fish in Europe (in France, it is called loup de mer).
There are also freshwater basses, although they taste less. There is also a hybrid bass - a cross between striped bass and white bass, commonly called hybrid striped bass. This hybrid is fast-growing and carries more meat, which also stays edible for a couple of weeks. Of course, fresh fish is usually the prefered choice. Best seasons for basses is usually autumn and winter.
Chilean sea bass is a fatty fish (15%), not actually a bass but Patagonian toothfish. It can be quite big, like an adult man. Its flesh has big flakes and is rich in flavor. It also tolerates overcooking.
Salmons
Salmon is very popular and has a nice pink color, due to its diet. They are interesting in that they spawn in freshwater rivers, live there for a few years, then go out into the sea to eat and grow bigger (1-4 years), and then return to their "homes" to mate and give rise to new salmons. If you catch a salmon that is in its migratory phase of life, don't bother to eat it because its flesh is mushy. Salmons are popular aquaculture fish, and the ones grown up in the farms are more fat than the wild salmons (who are more firm). Their characteristic is the little dorsal "fin" near the tail (they also have a normal dorsal fin). It has a silvery skin with black dots, can weigh up to 45 kg, and become 150 cm long. However, most of the salmons we get are much smaller than that, usually 3-5 kg. The best season for wild salmon is summer and autumn.
Trouts
Trouts are similar to salmons, although they live in freshwaters. Since they don't eat the colored ocean crustaceans, their flesh is not very colored. The most popular trout is probably the rainbow trout (often coming from farms). The characteristic sign of a rainbow trout is the red-violet band along its sides, and it also has black dots on its fins. It can grow to about 15 kg, but the wild rainbow trout is usually around 1 kg when caught. It is of good quality all year round.
Cod, haddock, and others
The most eaten fish species are the ones of the cod family: cod, haddock, hake, pollock, whiting - known for their firm, nicely textured flesh with subtle flavor. This characteristic is due to their lifestyle and environment - they don't move very much and they live near the ocean bottom, so they don't express many enzymes that take care of their metabolic needs. Cod family fish has three dorsal fins and two anal fins. Body is long and the head is relatively big, it has a protruding upper jaw, and it can weigh up to 50 kg. It can be colored differently, depending on where it comes from, e.g cod that lives near the sand bottoms are green-gray. Cod is a good all year round fish. Haddock is similar to cod, but it has a characteristic black spot above the pectoral fins. The back is dark-colored, and the belly is white. It is best during september-april.
Carp
Carp lives in freshwater, and is the largest fish family on Earth. It is very popular in aquaculture, mainly due to its high tolerancy to variety of temperatures and oxygen levels. Carp is a bony fish, has a rough texture, and carries some fat. It has a high body, a long dorsal fin, it has small "beard" hairs, and is colored green-gray or lightly golden. It can weigh up to 30 kg, although normal weight for wild-caught carp is around 3 kg. A relative of carp is catfish, although it is not at all that bony. Both fish may taste little muddy, especially during autumn and summer, but they can be eaten all year long.
FOR THE NUTRITIONAL VALUES OF THE FISH OPEN THIS EXCEL FILE - CLICK HERE