What part of fish is collagen? A deep dive into marine sources

October 24, 2025 •

4 min read

An estimated 75% of fish byproducts from processing industries are often discarded, yet these materials are exceptionally rich in protein. This presents a valuable opportunity to extract marine collagen, but many wonder: what part of fish is collagen, and why is it so beneficial?

Quick Summary

Fish collagen is primarily sourced from the skin, scales, and bones of fish. This marine-based protein, predominantly Type I collagen, is known for its high bioavailability and supports skin, joint, and connective tissue health.

Key Points

Primary Sources: The majority of usable fish collagen is extracted from the skin, scales, and bones of fish.
High Bioavailability: Marine collagen is known for its small peptide size, allowing for faster and more efficient absorption by the body compared to other collagen sources.
Predominantly Type I: Collagen from fish skin, scales, and bones is mostly Type I, which is the most abundant type in the human body and vital for skin and connective tissues.
Type II from Cartilage: Fish cartilage, particularly from species like sharks, is a source of Type II collagen, which is beneficial for joint health.
Sustainable Sourcing: Utilizing fish byproducts like skin and scales for collagen production helps reduce waste in the fishing industry.
Extraction Process: Collagen is typically extracted from fish through a hydrolysis process using acids and/or enzymes, which breaks it down into small peptides for supplements.

Understanding Fish Collagen Sources

Fish collagen, also known as marine collagen, is a potent source of this vital structural protein, and it is derived from several parts of the fish that would otherwise be considered waste. Unlike mammalian collagen, which has faced scrutiny due to disease concerns, marine collagen is recognized as a safer, more sustainable, and often more bioavailable alternative. For the supplement and cosmetic industries, the focus is on utilizing the abundant Type I collagen found in specific fish tissues.

Fish Skin

Fish skin is arguably the most recognized and richest source of marine collagen. It is particularly abundant in Type I collagen, the same type that makes up the majority of human skin, bones, and connective tissues. In commercial production, fish skins are a primary byproduct of the fillet industry. Notable species utilized include cod, salmon, and tilapia, each offering a substantial yield of high-purity collagen. For example, studies have shown that the thick skin of species like parrotfish contains significant collagen, leading to higher gelatin yields. The collagen from fish skin is prized for its ability to enhance skin hydration and elasticity.

Scales

Another significant source often overlooked is fish scales. These are a biocomposite material, consisting of Type I collagen fibers interwoven with calcium salts. For extraction, the scales must undergo a demineralization process to isolate the collagen. Research has revealed that collagen from fish scales, particularly from tropical freshwater species like tilapia, can possess a remarkably high denaturation temperature due to its amino acid content and structural bonds, making it suitable for therapeutic applications. Sourcing collagen from scales further leverages materials that are typically discarded as waste, promoting a circular economy within the fishing industry.

Bones

Like mammalian bones, fish bones are an excellent reservoir of collagen, again primarily Type I. Studies confirm that after the skin, fish bones contain the highest protein levels and collagen content. The collagen in bones is part of a hydroxyapatite network that provides strength and structure. Extracting collagen from bones involves more intensive processing, including demineralization to access the protein-rich ossein. This ensures that a greater proportion of the fish is utilized, creating additional revenue streams from byproducts. Species such as cod and salmon are commonly used for bone-derived collagen.

Cartilage and Connective Tissues

While Type I collagen dominates in the skin, scales, and bones, cartilage is a key source for Type II collagen. This type is critical for joint health, as it is a major component of cartilage that cushions joints. Shark cartilage, in particular, is a well-known source of Type II collagen and is often used in supplements aimed at supporting joint mobility and reducing inflammation. Other connective tissues, including fins, ligaments, and swim bladders, also contain valuable collagen and are increasingly explored for extraction.

Marine vs. Bovine Collagen: A Comparison

Choosing a collagen supplement often comes down to source. Here's a comparison of marine and bovine collagen, two of the most popular choices, based on common criteria:


Feature	Marine Collagen	Bovine Collagen
Primary Source	Fish skin, scales, and bones	Cow hides, bones, and cartilage
Collagen Types	Primarily Type I	Types I and III
Bioavailability	Very high due to smaller peptide size, leading to faster absorption	High, but slightly lower than marine
Best For	Skin, hair, and nail health; anti-aging	Joint, gut, skin, and muscle support
Dietary Suitability	Suitable for pescatarians and those avoiding beef for religious/cultural reasons	Not suitable for pescatarians, vegetarians, or those avoiding beef
Allergen Potential	Possible risk for individuals with fish or shellfish allergies	Possible risk for those with beef sensitivities
Sustainability	Often considered more sustainable due to use of fish byproducts	Sustainability depends on sourcing (e.g., grass-fed vs. conventional farming)

The Extraction and Bioavailability Advantage

Marine collagen's superior bioavailability is a key selling point. The peptides derived from fish collagen typically have a smaller molecular weight than other sources, allowing for easier and faster absorption into the bloodstream. The extraction process for marine collagen involves several steps to achieve this. Raw materials like fish skin and scales are first cleaned and pre-treated to remove non-collagenous proteins and minerals. The collagen is then extracted using either an acidic solution (Acid-Soluble Collagen or ASC) or a combination of acid and enzymes, like pepsin (Pepsin-Solubilized Collagen or PSC). This hydrolysis breaks down the long, complex collagen triple-helix structures into smaller, more digestible peptides. These peptides are then precipitated, purified, and dried, often into a powder form ready for consumption. This process is not only efficient but also utilizes a valuable byproduct of the fishing industry, offering both environmental and economic benefits. Learn more about the potential of fish waste valorization in research through publications like this one: Fish skin as a biomaterial for halal collagen and gelatin.

Conclusion

So, what part of fish is collagen? The answer is multifaceted, encompassing the skin, scales, and bones, with cartilage offering a distinct type of collagen. These sources, which are often byproducts of the fishing industry, provide a sustainable and effective route to supplementation. Marine collagen, primarily Type I, is highly valued for its superior bioavailability and benefits for skin, hair, and nails. While bovine collagen offers a broader range of collagen types for overall support, marine collagen is an excellent choice for those with specific goals or dietary considerations. By utilizing these marine resources, we can convert waste into valuable health and beauty products, benefiting both consumers and the environment.

Frequently Asked Questions

The skin of a fish is typically the richest source of collagen, particularly Type I, followed closely by the scales and bones.

Marine collagen is often considered superior for skin health due to its higher bioavailability and smaller peptide size, allowing for faster absorption. Bovine collagen contains both Type I and Type III, making it a better option for broader support including joints and muscles.

Yes, eating fish skin, especially from collagen-rich fish like salmon and cod, can provide a dietary source of collagen. However, the collagen is in its native form and must be digested and broken down by your body, unlike pre-hydrolyzed supplements.

The majority of collagen in fish skin, scales, and bones is Type I collagen. Cartilage from certain fish, like sharks, contains Type II collagen.

No, fish oil and fish collagen are entirely different products. Fish oil is an oil derived from fatty fish tissues, while fish collagen is a protein extracted from the skin and bones.

Yes, fish collagen is often seen as a sustainable choice because it is sourced from byproducts of the fishing industry that would otherwise be discarded, helping to reduce waste.

Fish collagen is extracted through a process of hydrolysis, typically using acids or enzymes. This breaks the large collagen fibers down into smaller, highly bioavailable peptides that are then purified and dried.

For most people, marine collagen is safe. However, individuals with fish or shellfish allergies should avoid it. It is also important to ensure you source supplements from reputable brands to avoid potential heavy metal contamination, though high-quality brands typically test for purity.