Is Butter Fish Good for You? Separating Fact from Mislabeling Risks

December 15, 2025 •

4 min read

According to NOAA Fisheries, U.S. wild-caught butterfish is a sustainably managed and nutrient-rich choice, but the label 'butter fish' can sometimes lead to dangerous confusion with other species. This guide separates the facts from the risks to determine if butter fish is a healthy option for your diet.

Quick Summary

Authentic butterfish offers high-quality protein, B vitamins, and selenium, while a mislabeled imitation, escolar, contains indigestible wax esters that can cause digestive problems.

Key Points

Nutritional Value: Genuine butterfish is a great source of protein, B vitamins, and selenium, and some species offer significant Omega-3s.
The Escolar Problem: The term 'butterfish' is often mistakenly applied to Escolar, a fish containing indigestible wax esters that cause digestive distress.
Keriorrhea Risk: Consuming mislabeled escolar can lead to oily diarrhea (keriorrhea), nausea, and cramps due to the indigestible fats.
Know Your Species: To avoid risks, always confirm the specific species and look for reliable labels like 'U.S. Wild-Caught Atlantic Butterfish' or 'Sablefish'.
Purchase from Reputable Sources: Buying from a trusted fishmonger is crucial for ensuring accurate species identification and avoiding mislabeled products.
True Butterfish Is Safe: When properly identified, genuine butterfish is a safe and healthy choice with a delicate flavor and flaky texture.

The Nutritional Benefits of True Butterfish

When you purchase a genuine butterfish, such as the U.S. Atlantic species (Peprilus triacanthus) or the Alaskan Black Cod (sablefish), you are acquiring a fish with impressive nutritional credentials. These varieties are not only prized for their tender, delicate texture but are also packed with essential nutrients that support overall health.

Key Nutrients in Genuine Butterfish

High-Quality Protein: Essential for building and repairing tissues, true butterfish is a superb source of protein, helping to keep you full and supporting muscle mass.
Rich in B Vitamins: It provides a significant amount of niacin and vitamin B12. Vitamin B12 is crucial for nerve function and red blood cell production, with some types providing over 65% of the daily value in a single serving.
Source of Phosphorus and Selenium: These minerals are vital for bone health, energy metabolism, and immune function. Selenium also acts as a powerful antioxidant.
Healthy Fats and Omega-3s: While some species of true butterfish are leaner, others, like Black Cod, are renowned for their high levels of beneficial Omega-3 fatty acids, which are important for heart health and reducing inflammation.

The Healthiest Butterfish Choices

To reap the health benefits without the risk, focus on reliably sourced species. Your best options include:

U.S. Wild-Caught Atlantic Butterfish: A federally managed, sustainable option known for its excellent nutrient profile.
Sablefish (Black Cod): Often referred to as butterfish for its rich, buttery texture and high omega-3 content.
Avoid ambiguity: When the label is unclear, ask your fishmonger for the specific species name to ensure you are not buying a dangerous impostor.

The Critical Risk of Mislabeling: Escolar and Keriorrhea

One of the biggest concerns with 'butter fish' is the frequent mislabeling of escolar (Lepidocybium flavobrunneum). Escolar, a deep-water fish, is also known as 'oilfish,' 'walu,' or 'super white tuna' and is notorious for causing unpleasant digestive issues. Its flesh contains a high concentration of indigestible wax esters (gempylotoxin) that the human body cannot properly process.

What Happens When You Eat Escolar?

Eating escolar can lead to a condition called keriorrhea, characterized by oily, orange or yellow fecal discharge, which is not absorbed by the body. Other symptoms may include:

Nausea
Vomiting
Abdominal cramps
Diarrhea
Headache

These symptoms can appear a few hours after consumption and typically last for 24 to 48 hours. The risk of these side effects has led to the banning or restriction of escolar sales in several countries, including Japan and Italy.

Comparison: Real Butterfish vs. Impostor Escolar


Feature	Genuine Butterfish (e.g., U.S. Atlantic)	Escolar (Mislabeled as Butterfish)
Taste & Texture	Delicate, flaky, mildly sweet flavor	Rich, intensely buttery flavor, velvety texture
Primary Fat	Healthier, digestible oils and fats	Indigestible wax esters (gempylotoxin)
Nutritional Profile	Excellent source of B vitamins, protein, and selenium	Good source of protein and fats, but the fats are indigestible
Safety for Consumption	Generally safe for most people	High risk of gastrointestinal distress (keriorrhea)
Regulation	Sustainably managed in U.S. waters	Banned or restricted in many countries due to health risks
Consumer Advice	Look for certified labels like 'U.S. Wild-Caught'	Avoid, especially in large quantities or if you have sensitive digestion

A Guide to Safe Butterfish Consumption

To avoid the unpleasant side effects of mislabeled fish and enjoy the true benefits of butterfish, follow these tips:

Ask for the Scientific Name: When in doubt, ask your fishmonger for the species' scientific name to confirm it's not Escolar.
Purchase from Reputable Sources: Buy from a trusted fishmonger or market that can provide accurate information about the fish's origin and species.
Check the Label: Look for specific species names like 'U.S. Wild-Caught Atlantic Butterfish' or 'Black Cod' rather than just 'butterfish.'
Practice Portion Control: If you are trying a potentially unknown butterfish for the first time, eat a small portion to gauge your body's reaction.
Opt for Low-Risk Cooking Methods: Grilling or baking can help reduce some of the oil content in wax-ester-containing fish, although it will not eliminate the risk entirely.

Conclusion: Is Butter Fish Good for You?

Ultimately, true butter fish is good for you, offering a range of vitamins, minerals, and healthy fats that can be a valuable addition to a balanced diet. The real danger lies in the widespread and deceptive practice of mislabeling. By being an informed consumer and purchasing from reliable sources, you can confidently enjoy this delicious and nutritious seafood without the associated health risks. Always prioritize knowing the specific species you are purchasing to ensure a safe and healthy meal.

For more information on sustainable seafood practices, you can visit the official NOAA Fisheries website: https://www.fisheries.noaa.gov/.

Frequently Asked Questions

Genuine butterfish (like U.S. Atlantic species or Sablefish) is a tasty and healthy fish containing digestible fats and nutrients, while escolar contains indigestible wax esters that can cause severe gastrointestinal issues.

Real butterfish is a good source of high-quality protein, niacin, Vitamin B12, phosphorus, and selenium. Certain types, like Black Cod (sablefish), are also rich in healthy Omega-3 fatty acids.

The side effects, known as keriorrhea, include oily, orange or yellow anal leakage, abdominal cramps, diarrhea, and nausea. These symptoms are caused by the indigestible wax esters in escolar.

While authentic butterfish is not banned, some countries, including Japan and Italy, have banned or restricted the sale of escolar due to its potential to cause digestive distress.

The best way is to purchase from a reputable vendor and look for specific labels such as 'U.S. Wild-Caught Atlantic Butterfish' or 'Black Cod' (sablefish). If the label is vague or only says 'butterfish,' ask for clarification.

No, while grilling or baking can reduce some of the oil content, it does not completely eliminate the indigestible wax esters that cause keriorrhea and other symptoms. It is best to avoid escolar entirely.

Individuals with sensitive digestive systems, inflammatory bowel conditions, or those who are pregnant should be particularly cautious and avoid mislabeled butterfish (escolar). It's safest to consume authentic butterfish from a known source.