Monkfish: a lean fish studied mostly as part of a group

We found no trial of monkfish on its own, so the best evidence is about lean fish as a group. A meta-analysis of 18 to 21 randomized trials with about 1,400 people found that eating lean fish lowered blood triglycerides compared with eating no fish. The size of that drop is not in the abstract, and the full text is paywalled. Total cholesterol and lipoproteins showed no significant difference. Some pooled arms used fish-derived protein instead of whole fish, and none is named as monkfish. The fish itself is very lean. The UK table gives raw flesh 15.7 g of protein and 0.4 g of fat per 3.5 oz (100 g) at 66 calories, and the USDA record puts protein at 14.5 g. USDA also lists 36.5 micrograms of selenium per 3.5 oz (100 g) raw, 66 percent of the Daily Value, from two records with no measured spread between fish. In a randomized stable-isotope trial of 35 men, selenium from fish (trout in that study) was absorbed as well as selenate and retained better, and cooking changed neither.

The numbers, per 3.5 oz (100 g)

How much is actually in it

• USDA puts raw monkfish at 36.5 micrograms of selenium per 3.5 oz (100 g), 66% of the Daily Value, with 0.9 micrograms of vitamin B12 and 14.5 g of protein. — USDA SR Legacy record for Fish, monkfish, raw (n = 2 records) Evidence E source
  Selenium 36.5 micrograms per 3.5 oz (100 g) raw (66% DV), 46.8 cooked dry heat; vitamin B12 0.9 to 1.04 micrograms; protein 14.48 to 18.56 g
• The UK table gives raw monkfish flesh 15.7 g of protein and 0.4 g of fat per 3.5 oz (100 g), 66 calories, so it is a very lean white fish and the protein figure sits 8% above the USDA one. — CoFID 2021 record 16-092, Monkfish, flesh only, raw (n = 1 record) Evidence E source
  Protein 15.7 g, fat 0.4 g, energy 66 calories, sodium 18 mg, phosphorus 330 mg, potassium 300 mg per 3.5 oz (100 g); USDA protein 14.48 g

What your body absorbs

• In a randomized stable-isotope trial in 35 men, selenium from fish was absorbed as well as selenate, was retained better, and cooking did not change either. — 35 healthy male volunteers aged 18 to 50 in Norwich and Zeist, eating labeled trout processed two ways, labeled yeast or labeled selenate in four meals over two days (n = 35) Evidence B source
  Apparent absorption from fish similar to selenate; retention of fish selenium significantly higher than selenate (P<0.001); no difference between the two processing methods
• In a crossover trial in 20 Norwegian adults, four weeks of lean seafood as 60% of dietary protein raised median urinary iodine from 70 to 135 micrograms per liter and raised plasma selenium and arsenic. — 20 adults (7 men, 13 women), mean age 50.6, two 4-week balanced diets with lean seafood or non-seafood as 60% of protein, 5-week washout (n = 20) Evidence B source
  Urinary iodine median 70 to 135 micrograms per liter on lean seafood versus 58 on non-seafood (P<0.001); plasma selenium up versus down (P=0.001); urinary and plasma arsenic up (P<0.001)

What cooking and storage change

• For lean finfish under 5% fat, the USDA retention table keeps 90% of vitamin B12 after baking, broiling or frying and 85% after simmering with the liquid discarded. — USDA retention factors for the Finfish and Shellfish Products group, lean finfish below 5% fat Evidence E source
  Vitamin B12 retained 90% baked without drippings (2301), 90% broiled (2305), 90% fried without coating (2309), 85% simmered without drippings (2401)

What it does to your health

• A meta-analysis of 18 to 21 randomized trials with about 1,400 people found that eating lean fish lowered blood triglycerides against no fish but did not change cholesterol. — 1392 to 1456 participants in 18 to 21 crossover and parallel randomized trials of lean fish or fish-derived protein versus no fish (n = 1392-1456) Evidence A source
  Triacylglycerol lower with lean fish than with no fish; no significant difference in total cholesterol or lipoproteins; size of the reduction not given in the abstract
• Pooled cohort data link the highest lean fish intake with a 19% lower stroke risk than the lowest, based on five comparisons. — five prospective cohort studies with 5 comparisons for lean fish and 7 for fatty fish Evidence C source
  Relative risk 0.81 (95% CI 0.67 to 0.99) for lean fish, 0.88 (0.74 to 1.04) for fatty fish, highest versus lowest intake

Safety, limits and interactions

• In a New York market survey of 177 fish and lobster samples, monkfish had the highest average total arsenic of any species, 13,400 ng per gram. — 177 fish and lobster samples bought in stores and markets in New York State (n = 177) Evidence C source
  Highest average arsenic 13,400 ng/g in monkfish; all arsenic levels below FDA action levels for crustaceans and shellfish

What people believe that the data does not support

• In 2007 two people in Chicago were poisoned with tetrodotoxin by puffer fish that had been imported and sold as monkfish, which led to a recall in three states. — two people who ate home-cooked fish bought in Chicago, plus fish retrieved from the supplier lot (n = 2) Evidence D source
  Tetrodotoxin at high levels in meal remnants and in the supplier lot; genetic analysis identified Tetraodontidae; voluntary recall in three states and FDA import alert
• Monkfish is rich in selenium, but the EU refused the claim that selenium is necessary for normal cardiovascular function. — European Union food labeling, claim on selenium Evidence E source
  Claim status non-authorized

Who this works differently for

• FDA testing of 11 monkfish samples found mean mercury of 0.161 ppm, median 0.139 and maximum 0.289, which is in the moderate range for commercial fish. — 11 monkfish samples in FDA monitoring, 1994 to 2007 (n = 11) Evidence E source
  Mercury mean 0.161 ppm, median 0.139, standard deviation 0.095, minimum not detected, maximum 0.289
• The only human study naming anglerfish is a Korean survey of 278 older adults, where those who knew more about taurine ate anglerfish more often, with no difference in cognition. — 278 Korean adults aged 65 and over without dementia, 76 men and 202 women, questionnaire and interview (n = 278) Evidence C source
  Higher taurine knowledge linked to more frequent anglerfish and other seafood intake (p<0.01); no significant difference in cognitive function scores

What is still unknown

• Arsenobetaine, the fish arsenic usually treated as harmless, was linked with hypertension in a Japanese survey of 2,676 residents and raised blood pressure in mice. — 2,676 Japanese residents with fasting urinary arsenic speciation, plus a 4-week mouse exposure study (n = 2676) Evidence C source
  Urinary arsenobetaine consistently associated with hypertension prevalence independent of sodium; human-equivalent dose raised blood pressure in mice

The bottom line

For cooking, the USDA table for lean fish under 5 percent fat keeps 90 percent of vitamin B12 after baking, broiling or frying and 85 percent after simmering with the liquid thrown away. Those factors are set for the group. In a crossover trial of 20 Norwegian adults, four weeks of lean seafood as 60 percent of protein raised median urinary iodine from 70 to 135 micrograms per liter, and plasma selenium and arsenic rose too. That was cod-type fish. Observational data pooled from cohort studies link the highest lean fish intake with a 19 percent lower stroke risk than the lowest (relative risk 0.81, 95% CI 0.67 to 0.99), an association whose upper bound sits close to no effect. The EU refused the label claim that selenium is necessary for normal cardiovascular function, which means the evidence did not carry when it was assessed. Who should be careful. In a New York survey of 177 fish and lobster samples bought before 2010, monkfish had the highest average total arsenic of any species, 13,400 ng per gram. All levels were below the FDA action levels set for crustaceans and shellfish, and the survey did not split the arsenic into its forms. Arsenobetaine, the fish arsenic usually treated as harmless, was linked with hypertension in a Japanese cross-sectional survey of 2,676 residents, a single first report that raises a question and settles nothing. FDA testing of 11 monkfish samples from 1994 to 2007 found mean mercury of 0.161 ppm and a maximum of 0.289, a moderate level for commercial fish that matters most in pregnancy and for young children. One documented poisoning came from fish that was not monkfish at all. In 2007 two people in Chicago were poisoned with tetrodotoxin by imported puffer fish sold as monkfish, which led to a recall in three states.

Sources

1. mkf-r4-01 · USDA FoodData Central SR Legacy, dataset
   Fish, monkfish, raw (FDC 173676, SR Legacy, Finfish and Shellfish Products): selenium 36.5 ug per 100 g = 66% DV; vitamin B12 0.9 ug = 38% DV; protein 14.48 g = 29% DV; range over 2 records: selenium 36.5-46.8, B12 0.9-1.04, protein 14.48-18.56; Foundation samples 0
   USDA FoodData Central, SR Legacy, FDC 173676 · checked 2026-09-29
2. mkf-r4-02 · CoFID 2021 dataset
   Monkfish, flesh only, raw (CoFID 2021, code 16-092): Protein 15.7 g; Fat 0.4 g; Energy 66 kcal; Sodium 18 mg; Phosphorus 330 mg; Potassium 300 mg per 100 g
   CoFID 2021, Public Health England / OGL v3.0, code 16-092 · checked 2026-09-29
3. mkf-r4-04 · randomized controlled trial in humans
   Fish selenium is a highly bioavailable source of dietary selenium. Cooking did not affect selenium apparent absorption or retention from fish. Selenium from yeast is less bioavailable.
   Eur J Clin Nutr, 2004 · checked 2026-09-29
4. mkf-r4-05 · randomized controlled trial in humans
   UIC increased after 4 weeks of the lean-seafood intervention to 135 (110, 278) µg/L, but not after the non-seafood intervention [58 (33, 91) µg/L] (P diet-effect < 0.001). Fasting plasma Se increased in the lean-seafood intervention and decreased in the non-seafood intervention (P diet-effect = 0.001).
   Eur J Nutr, 2021 · checked 2026-09-29
5. mkf-r4-03 · USDA Table of Nutrient Retention Factors, Release 6, dataset
   USDA-RETN-R6:2301 FINFISH,<5%FAT,BAKED,WO/DRIPPINGS vitamin B12 90%; USDA-RETN-R6:2305 FINFISH,<5%FAT,BROILED,WO/DRIPPINGS 90%; USDA-RETN-R6:2309 FINFISH,<5%FAT,FRIED,WO/COATING 90%; USDA-RETN-R6:2401 FINFISH,<5%FAT,SIMMERED,WO/DRIPPING 85%
   USDA Table of Nutrient Retention Factors, Release 6, 2007, codes 2301, 2305, 2309, 2401 · checked 2026-09-29
6. mkf-r4-06 · meta-analysis of RCTs
   Meta-analysis of data from 18 to 21 eligible crossover and parallel-design RCTs with a total of 1392 to 1456 participants found triacylglycerol-lowering effects for lean fish compared with no fish consumption. Lean fish intake showed no significant differences related to total cholesterol or lipoprotein levels.
   Nutr Rev, 2021 · checked 2026-09-29
7. mkf-r4-07 · meta-analysis of cohort studies
   Compared with the highest category of intake with lowest category, the summary relative risk was 0.88 [95% confidence interval (CI), 0.74-1.04] for fatty fish intake and 0.81 (95% CI, 0.67-0.99) for lean fish intake.
   Lipids Health Dis, 2018 · checked 2026-09-29
8. mkf-r4-08 · cross-sectional contaminant survey of food samples
   The highest average arsenic level (13,400 ng/g) was found in monkfish.
   J Food Prot, 2010 · checked 2026-09-29
9. mkf-r4-10 · case report with public health investigation
   Both the Chicago retailer and the California supplier denied having sold or imported puffer fish but claimed the product was monkfish. However, genetic analysis and visual inspection determined that the ingested fish and others from the implicated lot retrieved from the supplier belonged to the family Tetraodontidae.
   J Food Prot, 2009 · checked 2026-09-29
10. mkf-r4-12 · regulatory register entry
    POL-HC-7918 Selenium Selenium is necessary for normal cardiovascular function. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7918, snapshot 2026-09-21 · checked 2026-09-29
11. mkf-r4-09 · agency monitoring data
    MONKFISH | 0.161 | 0.139 | 0.095 | ND | 0.289 | 11 | FDA 1994-2007
    US FDA, Mercury Levels in Commercial Fish and Shellfish (1990-2012) · checked 2026-09-29
12. mkf-r4-13 · cross-sectional study in humans
    Compared to the LAG, the HAG members more frequently consumed foods such as webfoot octopus, whelk, dried anchovy, dried shrimp, mackerel, anglerfish, skate, short-necked clam, shrimp, and dried squid (p < 0.01). There was no significant difference in CF scores between the LAG and HAG.
    Adv Exp Med Biol, 2019 · checked 2026-09-29
13. mkf-r4-11 · cross-sectional study in humans
    Unlike dimethylarsinate, monomethylarsinate, and inorganic arsenic, arsenobetaine, an organic arsenic species considered non-toxic, was consistently associated with the prevalence of hypertension independent of sodium exposure in both univariate and multivariate models.
    Environ Int, 2026 · checked 2026-09-29