About Ratfish Liver Oil

By Dan Corrigan   ∙   July 09, 2020   ∙   0 Comments

Who should consider adding ratfish liver oil to their supplement routine?

Here’s a snapshot of some of our customers and why they take Rosita® Ratfish Liver Oil:
  • Real foodies searching for a rare and special nutrient profile.
  • Those looking for a completely natural supplement that’s high in alkylglycerols.*
  • Families with children on the spectrum (especially those with taste sensitivity to fish).*
  • Anyone striving to improve and support their overall health, including the brain, and immune and circulatory systems.*

How is Rosita® Ratfish Liver Oil purified?

Each batch of Rosita® Ratfish Liver Oil is gently filtered for contaminants without the use of high heat or solvents. This way ensures our fish liver oils remain raw and still yield extremely low levels of contaminants that are well below the strict European standards. Every batch of our Ratfish Liver Oil is tested for PCBs and dioxins to ensure the oils meet these standards. The results are posted here

No other ratfish liver oil company goes through the effort and expense to provide this information. 

Please note, as with all raw sea foods, there will be some contaminants. To offer a fish liver oil with zero contaminants would call for molecularly distillation (high heat) or deodorization of the oil. Both of these processes use very high temperatures which destroy the natural vitamin A, D  and E in the oil. Rosita® will never compromise the nutrient quality of the oil and the very low levels of contaminants provide the best option for those seeking natural, full-spectrum vitamins and omega fatty acids. Rosita® fish oils will always be processed to be wild-caught, fresh and raw.

Is Rosita® Ratfish Liver Oil the same as skate liver oil?

Some misinformed people claim that the skate fish is related to the same fish species as the ratfish (Chimaera monstrosa Linnaeus, 1758). The only similarity between the two is that they are both cartilaginous fish. Some are even claiming that the skate fish is the same fish under a different name. 

Please know that Rosita® Ratfish Liver Oil is completely different than skate oil. If you do the research, you will find there is just no comparison. Ratfish are distinct from skates, rays and sharks, with a different nutrient profile. In fact, there is no other fish like the ratfish on the planet. It is the only species in the family of Chimaera. It is one of the oldest fish species alive today.

How is the liver oil extracted from the ratfish?

The ratfish are exclusively harvested by local artisanal fishermen from the deep, crystal clear and unpolluted waters of the spectacular Norwegian Helgeland fjords. The fjords are framed by the rugged peaks of stunning mountain ranges, including the “Seven Sisters,” which are bathed in the light of the midnight sun, or set against the flickering Northern Lights which dance across the sky. The special natural environmental conditions of this gorgeous and unspoiled area come together in harmony, and contribute to the production of our high quality, truly unique oil.

First, the ratfish are wild-caught from small fishing boats with shelter decks, rather than commercial fishing boats. 

Maintaining the natural quality of fresh-caught ratfish depends on careful post-harvest handling. As such, our fishermen are given strict guidelines, which include protecting them from exposure to temperatures greater than that of refrigeration, by icing the fish immediately upon harvest. These practices, rare in commercial fisheries, ensure that we receive the fish as fresh as the moment they were pulled from the waters.

Once harvesting is complete, the fish are quickly ferried to shore. They are then carefully inspected, and only fish of a certain age and size are used. The livers from larger size fish (fish beyond a certain weight) are never used to produce our oil.

To produce the freshest oil, the livers from healthy fish should be removed as soon as possible. We carefully remove and inspect the ratfish livers by hand, and only the best quality livers are selected for extracting the oil. The liver of the ratfish, when healthy and fat, is cream-colored, and so soft that a finger may be pushed through it. Leaner livers deepen in color to a reddish or nearly black hue – these are never used to produce our oil.

We make sure the livers are very carefully handled and never exposed to high temperatures or chemicals. Rough handling of the liver can cause it to bruise, promoting degradation of the liver and lowering the quality of the oil produced (only the undamaged, fresh livers are suitable).

Strict control of the temperature before and during the ratfish liver oil extraction process is also central to the quality of the final product.

The livers finally selected are carefully cleansed by washing in pure cold water. The wild harvested ratfish livers then undergo our proprietary, unique and completely natural extraction process. This natural process occurs as soon as possible after harvesting (to avoid any chemical changes from taking place), in a clean and odor-free environment. 

Here’s how it works:

We create a gentle shift in temperature, from the icy cold water that the fresh livers are submerged in upon harvest, to below-room temperature. This shift naturally triggers the release of the oil. 

This shift is also done in the total absence of heat, which protects the oil’s nutritional value. Just as important, we never subject the livers to chemical treatment, solvents, mechanical devices, rendering, Peter Möller’s method (steam), distillation, winterization, putrefaction, decomposition, alkali refining, bleaching, deodorization or freezing. We take every precaution to preserve the therapeutic properties of cod liver oil and its natural abundance of nutrients.

This process is so are because the only way to carry out this subtle, gentle temperature shift is by controlling the entire process from fish to bottle. Great care for the livers is taken throughout each step, so they maintain the optimal temperature that allows the fresh oil to naturally release. Please note that the process to release the ratfish liver oil is the same we use for our cod liver oil

Immediately after the oil is released, it is very lightly filtered, with the help of a special method that uses gravity only, at low temperatures. This method simply removes particles of liver tissue, without refining the oil. In contrast, conventional procedures remove most of the healthy, fat-soluble vitamins, and therefore, commercial producers will add synthetic vitamins to make up for the loss.

What is a ratfish?

Ratfish liver oil is derived from the liver of a little- known group of shark relatives known as the Chimaeras (Chimaera monstrosa Linnaeus; common name: ratfish, rabbitfish or ghost shark). Chimaera takes its name from the Greek chimaera, a mythical monster with the head of a lion, body of a goat and the tail of a dragon. It is the offspring of Echinda and Typhon.

The Chimaeras are a primitive group of fish, with skeletons composed of cartilage instead of bone, dating back more than 300 million years. They are true survivors from before the dinosaurs, and have changed very little since. They may actually be the oldest and most enigmatic groups of fish alive today. 

The ratfish is found in all the world's oceans, close to the bottom, at depths of 300 to 500 meters, with a reported maximum depth of 1,663 meters. These fish are almost half shark and half ray, with smooth skin, big sparkling green eyes designed to see in the dark depths, a rabbit-like face, and a small mouth surrounded by large lips. The nose of the ratfish is studded with electric sensors that can detect the faint electrical signals given off whenever bottom-dwelling prey – including crabs, snails, starfish, marine worms, urchins, clams, shrimp, and small fish – use their muscles, and is sensitive enough to detect their heartbeats. Ratfish bodies taper to an exceptionally long threadlike tail, and together with their rodent-like teeth designed for crushing the shells of their prey, has earned them the common name "ratfish."

There is limited fishing for this species of fish, which are not a popular food source, although they are edible and their white meat is tasty. However, following the removal of the liver, head and innards, there’ s actually less than 10% left for use as a food source. A major reason for this is the size of the liver, which makes up a large proportion of the total mass of the fish.

The liver of the ratfish constitutes approximately 60% of its total body weight, and contains an exceedingly high proportion of oil. The oil content is around 60%, but can in some instances be as high as 80% of the wet liver weight. The large oily liver plays an important role in the maintenance of neutral buoyancy.