Why Do Fish Have Scales and The Importance of Fish Scales

If you have ever been to a fish market or caught your own fish, you will already know that most fish have scales, you know, those plastic flakes that cover their body that tend to make a mess and are so difficult to remove. Why Do Fish Have Scales?

Fish scales act like armor protecting fish from scrapes on rocks & branches protecting the fish from injury, & shielding fish from predators. Scales provide defense against parasites. They make fish more aerodynamic & help them move through the water faster up, down, or sideways without changing speed.

The scales of a fish contain a variety of pigments that can give the fish different types of colors. The scales form rows along the lateral line of the fish and help in detecting vibrations in the water as it acts as a sensory receptor.

Why Do Fish Have Scales


Why Do Fish Have Scales; Contrary to popular belief, not all types of fish possess scales. Species devoid of scales encompass catfish, sharks, rays, chimeras, skates, moray eels, sturgeons, paddlefishes, sailfin blennies, combtooth blennies, hagfishes, and lampreys. These species have evolved alternative defenses to scales over the years. The Role of Scales in Fish Anatomy and Why Fish Have Scales is a mystery to so many fishermen. Scales are critical elements of fish anatomy, serving a multitude of purposes beyond being merely a skin layer.

Their role fluctuates depending on the aquatic environment. Over generations, fish scales have evolved to operate as a protective armor, safeguarding the species from predators and physical harm caused by abrasions with rocks and branches. The Protective Features of Fish Scales Fish scales serve as a robust barrier against potential injuries, predators, and parasites. This natural shield offers a strategic advantage by enhancing the fish’s defense, making it a swift swimmer.

Scales fine-tune the fish’s aerodynamics and facilitate speedy movement through water, whether it’s upward, downward, or sideways, without changes in velocity. The Role of Scales in Sharks’ Mobility. Interestingly, sharks commonly utilize their scales to swiftly change directions and reduce drag. Furthermore, by examining the arrangement of scales on a fish’s body, one can make an educated guess about the creature’s age.

The Importance of Slime Coat under Fish Scales all fish secrete a slime coat from beneath their scales, which offers an additional layer of protection against infections and parasites. Some species even have a toxic slime layer that acts as an extra defense line against predators.

Fish Scales Regeneration Fish are capable of regrowing lost scales. Fish that have suffered minor injuries usually regenerate their scales fairly rapidly. However, during the healing phase, the unprotected areas become more susceptible to diseases, fungi, and parasites, emphasizing the critical role of scales in safeguarding the fish’s well-being.


Different Types of Fish Scales


When we ponder the question, “Why Do Fish Have Scales?” it’s important to understand the various scales adorning different fish species. Our exploration leads us to the discovery of “Different Types of Fish Scales.” There are four major types of scales found on fish, and each type has many variations.

Firstly, placoid scales, often spotted on sharks and rays, maintain a distinctive flattened rectangular shape. These interesting scales do not alter in size as their host grows, instead, new scales spring up to fill any vacant space as the fish gets bigger.

The second type is the cosmoid scales, evident on the bodies of fossil fishes and lungfish. Sharing almost the same size and shape as placoid scales, cosmoid scales are sturdy, boasting two layers of bone, coupled with a layer of dentine and vitrodentine.

Let’s just say, these aren’t the sort of scales you’d want to nibble on!
Ganoid scales are next on the list, forming a rhomboidal shape with articulating peg and socket joints sandwiched between them. This fascinating style of scale can be found on an array of fish, including sturgeons, bowfin, and paddlefish, among others.

Finally, we have the lustrous cycloid and ctenoid scales- the regular choice for most bony fishes. These scales stand out due to their special attribute of flexibility. This is facilitated by the overlap of the anterior and posterior parts of the scale, creating a fluid, moveable surface. Ctenoid scales have a comb-like edge with small bony projections along the posterior edge known as ctenii. The fish is further protected by these edges that protrude because they give the scales a rough feel and cause them to interlock. Fish of many kinds, such as perch and bass, have ctenoid scales.

The terms cycloid and ctenoid derive from Greek words that describe their shape and look. Did you know that the word cycloid means circle? Ctenoid is short for comb-like, which defines how the fish’s scales appear. Cycloid and ctenoid scales can be found in a wide range of fish, from little minnows to large game fish. Both types of scales are found in a wide variety of boney fish families, including perch (Percidae), sunfish (Centrarchidae), and salmon (Salmonidae).

Now, some species of flatfish such as flounders and soles exhibit a mix of both types. On the eyed side of the flatfish’s body, you will spot ctenoid scales, whilst the blind side is adorned with cycloid scales. Such diversity showcases the splendid adaptability of our aquatic friends. In summary, whether you’re an angler, a marine biologist, or a humble fish enthusiast, understanding these different types of fish scales plays a crucial part in getting to know the underwater world at MyWaterEarth&Sky.

The Benefits of Scales on Fish


Fish have scales that accommodate two crucial skin layers. The outer layer, known as the epidermis, produces a mucus-like substance. This substance guards the fish’s skin against any harmful bacteria and fungi, ensuring a healthy habitat. The inner layer, referred to as the dermis, consists of tough bony material, acting as the sturdy support system for the fish.

In understanding The Benefits of Scales on Fish, it’s insightful to view each scale as a life ring. These rings chronicle the fish’s age, adding more depth to our understanding of this marine creature. However, fish scales do much more than just tell time. They act as formidable protective barriers that shield the fish from health-endangering agents like parasites and bacteria.

The role of fish scales inefficient movement through water can’t be understated. It’s fascinating to observe how the hardness of the scales directly impacts the fish’s speed. Harder scales result in a faster fish due to less water resistance, increasing the fish’s survivability against possible threats. Conversely, fish with lighter and softer scales enjoy the advantage of flexibility and quicker pace due to reduced weight.

The importance of fish scales extends to their adaptive capacities for camouflage. By blending seamlessly with the environment, they help the fish elude any lurking predators.
All fish secrete a slime coat beneath their scales. This slime layer not only keeps the fish moist but also provides additional protection against infections and parasites. In some cases, the slime coat is toxic, serving as another effective line of defense against predators. Altogether, these features show why fish scales are critical to the survival and adaptation of fish in their natural habitats.

Why Don’t Deep-Sea Fish Scales Grow


Among the vast array of creatures residing within our oceans, many embody a common trait – fish scales. These scales can exhibit a diverse range of appearances; from opaque or transparent to vibrantly colored. They serve as a testament to the kaleidoscopic nature that defines marine life. Nonetheless, there exists a number of ocean fish that go against the grain, completely devoid of scales. Like a fingerprint, the unique nature of fish scales, or lack thereof, is largely influenced by the specific habitats and conditions in which these species thrive.

The question arises, why don’t deep-sea fish scales grow? The world under the sea is as varied as it is mysterious, with inhabitants that have adapted in unique ways to survive. There are several fish species that have, over time, foregone the common scale covering. In the place of scales, these fish have evolved different defensive mechanisms against predators, parasites, and illness.

Scaleless fish often display a thick layer of slippery slime or are armored with bony plates to enhance their defense. Such variations in scale appearances and functions are influenced by the variety of habitats within the ocean. This ranges from serene lakes and muddy flats to the intense conditions of the open ocean. Some fish with no scales include sharks, stingrays, catfish, and sturgeon.

The sheer diversity of fish species and their respective adaptations are what make marine life as captivating as it is. Some fish bear legendary scales while others ascend to challenges with alternative features. The evolution of fish over the course of millions of years, adapting to their environments, is what has brought about this tremendous variety. One could say that in the ocean, where life began, the true essence of biodiversity, survival, and evolution is on full display.



Do Fish Scales Grow Back (Scale Regeneration)


Unlike reptiles that shed their skin to accommodate growth, most fish species don’t shed their scales. In fact, fish scales are rather akin to human skin and they share features such as a blood supply, enabling them to grow alongside the fish. Remarkably, an intriguing exception to this is the swordfish, which flaunts scales during its juvenile phase only to lose them all upon reaching maturity.

Indeed, fish scales do grow back, functioning remarkably similar to our fingernails. In circumstances wherein the fish has undergone minor trauma or suffered bacterial infections, you’ll find that their scales regenerate fairly quickly. Naturally, there’s a brief period during which the damaged area remains inadequately protected.

This can make the fish more susceptible to diseases, fungus, and parasitic infections. As new scales form, they usually appear smaller and lightly pigmented, marking another testament to the fascinating adaptability of fish scales. So, the next time you look at fish in your net or at the reef, take a moment to appreciate the science behind their scales you’ve learned here on MyWaterEarth&Sky.


Removing Scales From Fish


Fish scales serve several vital functions that enhance their survival in water. They not only help in providing a protective barrier against predators and diseases but also assist in regulating body temperature. Understanding the importance of scales and their role directly contributes to their proper handling and preparation for consumption.

For those who relish the taste of fish skin, descaling the fish becomes a critical step before cooking. The technique is simple and requires careful handling. Boil your catch in water for a bit, subsequently draining the water and giving the fish a cold rinse.

Alternatively, a tool as commonplace as a vegetable peeler does the job as well. It’s crucial that you don’t exert too much force as this might damage the delicate scales, leading to an unwanted mess.
A unique approach involves cooking the fish with the scales and skin intact. On completion of the cooking process, the skin, loosened by the heat, can be removed with relative ease, along with the detached scales.
Appreciating why fish have scales aids in handling them, from catch to plate. Remembering their importance ensures their beneficial qualities aren’t lost in the kitchen.


Can You Eat Fish Scales


Did you know that fish scales are indeed edible? Though not necessarily appetizing for all, some find their distinct flavor quite palatable. Originating from the mesoderm, the growth of scales considerably aligns with that of bones or teeth rather than reptile scales. Consuming fish skin is generally permissible provided it has been thoroughly cleaned and exterior scales have been detached.

Kosher regulations restrict the intake of fish without consuming both fins and scales. Salmon, for instance, is often eaten skin-on which is nutrient-dense, packed with valuable Omega 3. Fish scales are also celebrated for their high collagen content, a prized component in health food, pharmaceuticals, and various processing industries.
Unleash the inherent health benefits of fish with scales with MyWaterEarth&Sky’s easy-to-follow guides and enjoy this seafood delicacy with a rich heritage and savory flavor.



Understanding why fish have scales and their importance shows just how intricate and fascinating nature truly is. From protection to locomotion and even temperature regulation, scales play crucial roles in the survival of fish species in the habitat they live in. Appreciating these small details can increase our respect for the sea’s creatures and our role in maintaining their habitats’ integrity. At MyWaterEarth&Sky we believe in nurturing this respect and understanding for all forms of marine life which is central to our commitment towards sustainable fishing and an enriched fishing experience.



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JimGalloway Author/Editor


References: Science ABC- What Are The Different Types Of Fish Scales?




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