All fish have scales

Fish scales: the second skin of the water dwellers

According to the scientific definition, scales are the skin covering of most fish, which are formed in the subcutaneous tissue and consist of bone plates. At least that's what it says in zoological books. But behind the fish scales there is a lot more worth knowing. The scales of the native fish are complex. Essentially, they consist of a transparent top layer and an underlying, bony base layer. It is reinforced with cartilaginous fibers and characterized by so-called growth rings, which are interrupted radially so that the scales remain flexible.

There are different types of flakes. We are interested in the two large groups of round sheds and comb sheds. The plakoid scales of the sharks are not real scales. The so-called enamel scales of the sturgeon consist of bone plates coated with a layer of enamel and are therefore not real fish scales.

Fish scales: characteristic features

In fishery science, round sheds are divided into six other shed types:

  1. Herring scales (small, tender, slightly peeling)
  2. Trout shed (small, round, without radial stripes)
  3. Cyprinid scales (large, hard, silvery to golden shiny, with tench small, inconspicuous)
  4. Pike scales (firm, typically folded)
  5. Eel scales (very small, embedded deep in the skin, barely visible)
  6. Tadpole scales (small, tender)

Perch belong to the ridge scales. Their scales are firmly attached to the skin and are toothed like a comb. That's why they feel so rough. Photo: BLINKER / O. Portrait

The scales of some fish are characteristically shaped, they can even be used to determine their former owners. In the cormorants' spits, for example, there are fish bones and indigestible scales. Their investigation gives sufficiently precise information about the food spectrum of fish-eating birds.

The large, silvery shimmering scales of our white fish are striking. In some species they are very thin and, like bleak, fall off easily when touched. Its scales with their special silver sheen were used to make artificial pearls. The solid, golden, shiny round scales of wild carp or the large scales of its cultivated forms called "mirrors" are characteristic. The network drawing on the chub is even an important distinguishing feature of its kind.

We find comb scales in our perch-like fish such as perch, ruff or pikeperch. The comb scales are small, lie firmly in the skin and show their tiny teeth. The posterior side of the scales protruding from the subcutaneous tissue is toothed. That's why the fish are rough to the touch. Photo: W. Hauer

Round and comb scales form a roof tile-like covering of the body surface. Because of this ideal arrangement, they do not hinder the mobility of the fish while swimming and still offer sufficient protection against injuries. The epidermis lies over the scales. It contains mucous cells that create a smooth, closed layer of mucus. If the scales are very small, as in the case of eels or tench, the mucus layer is reinforced. Scaleless fish like the catfish are very slimy, their skin is leathery and tough. The color cells are also here above the scaly layer. The fish lose their beautiful color when they are scaled; only the basic tone of the subcutaneous tissue, gray or green, remains.

Growth and regeneration

In summer the fish and with them the scales grow faster than in winter, so that clear annual rings form on the scales, which can be used to determine the age. Growth is also slowed down during spawning, it leaves traces on the scale rings. Specialists can learn a lot about the life history of the fish from the enlarged image of individual scales.

With this pike you can easily see the sideline. It enables us to perceive movements in the environment that we cannot reach with our senses. Photo: BLINKER / W. Tusks

The scales are created when the fish are young. The number of scales remains the same for the life of the fish, the scales grow evenly with them. Dandruff losses through injuries regenerate quickly. The newly formed scales grow very quickly, but often the harmonious, original scale pattern is no longer achieved. In the scar tissue of the dermis, the scales usually grow criss-cross.

Some fish scales are particularly noticeable. This includes the scales along the lateral line organ. The scales there have a clearly visible hole. This enables the sensory cells below to come into contact with the water. In some species such scales are also found outside the sideline. Difficult to distinguish cyprinid species such as the female nerfling and nerfling or the coregons (whitefish), which are very similar to one another, can be determined by the number of scales along the sidelines. Fish scales also have a mystical meaning in some areas. Some people put a scale of the Christmas carp in their wallet every year - so that it never runs out.

Remove fish scales properly

If you have been successful on the water and want to use the caught fish at home, you have to remove the scales before preparation. First of all, a distinction must be made between fish with loose scales (e.g. herring) and fish with fixed scales (e.g. pikeperch). While herring can easily be scaled under water with a wire net, the "dandruff treatment" for pikeperch, pike and Co. requires a little more work. Here are the steps:

1. Place the fish in a sink or plastic bag

2. Grab the fish by the end of its tail with one hand and hold it tightly

3. Grab a filleting knife with the other hand and stroke the blunt side from the tail end towards the head. The scales dissolve in a few minutes.

Tip: To avoid the loosened flakes from spreading in the kitchen, it is advisable to use tried and tested kitchen gadgets. Especially for those places that are hard to get to with a knife - for example the belly side. These are already available in specialist shops for little money.

Fish scales - can you see them?

Which fish is hidden behind the shed clothes? You can find the solution directly under the photo in the link.

  1. What fish is behind these scales?

    Photo: O.Portrat

    +++ Here is the solution +++

  2. Many predator anglers have already seen this great drawing. Which fish is it from?

    Photo: M. Werner

    +++ Here is the solution +++

  3. This shed dress sets color accents. Who do they belong to?

    Photo: O. Portrat

    +++ Here is the solution +++

  4. Which fish do these blue shimmering scales belong to?

    Photo: BLINKER

    +++ Here is the solution +++

  5. Who do these comb scales belong to?

    Photo: O. Portrat

    +++ Here is the solution +++