How limits are set
The standard for each analyte is the strictest maximum level set by any credible government regulator — among them the European Union, Codex Alimentarius, the US FDA, Australia/New Zealand, the Gulf states (GSO), and the national authorities of every jurisdiction that regulates the product — converted into Freshwater fish (tilapia, catfish, trout, carp)’s own as-consumed basis. It is a lookup of sovereign law, carrying at most one disclosed basis conversion where the law is written in another basis, and an explicit read-across where no government regulates the exact product. A certified product sits at or below every applicable sovereign limit at once.
Where no government regulates the exact product for an analyte, the standard does not go blank or invent a number: the limit is read across from the nearest government value for an analogous product, so a certified product still sits at or below a real sovereign limit. The ratchet tightens these after publication as surveillance warrants.
Master Limit Table
All values in ppb (µg/kg), as-consumed basis. 10 of 11 analytes carry a firm ceiling; the remaining 1 are toxic species bounded by their parent totals (species ≤ total, measured on every lot), so every analyte carries an enforceable ceiling. A brand meeting every value on a like-for-like basis qualifies for the mark.
| Analyte | HMTc limit | Binding basis |
|---|---|---|
| Lead (Pb) | 200 | strictest government ML (Fiji) |
| Inorganic arsenic (iAs) | 100 | strictest government ML (EU) |
| Total arsenic (tAs) | 1000 | strictest government ML (Singapore) |
| Mercury, total (tHg) | 300 | strictest government ML (EU) |
| Methylmercury (MeHg) | bounded | ≤ total tHg, measured every lot (see note) |
| Cadmium (Cd) | 50 | strictest government ML (GSO) |
| Nickel (Ni) | 2000 | government read-across (EU) |
| Total chromium (Cr) | 1000 | strictest government ML (Hong Kong) |
| Hexavalent chromium (Cr-VI) | 10 | government read-across (US-CA) |
| Tin (Sn) | 200000 | government read-across (EU) |
| Aluminium (Al) | 100000 | government read-across (China) |
Every claim analyte is equal at the gate. A product is certified only when every analyte is at or below 100% of its published government floor or disclosed read-across; above the limit, on any metal, it is not certified and carries no mark. Mercury is limited in both forms: total mercury (tHg) and methylmercury (MeHg) are separate ceilings that must both be met, set to the species-specific tier each government assigns (predatory fish carry the higher methylmercury ceiling, lower-trophic species the lower; where the total-mercury ceiling is stricter, methylmercury is bounded by it). Total arsenic (tAs) operates as a reflex screen to inorganic-arsenic (iAs) speciation, since most arsenic in seafood is non-toxic organic arsenobetaine. Every panel analyte carries a limit of record; where no government regulates the exact product (nickel, hexavalent chromium, aluminium, and non-canned tin), the ceiling is a disclosed read-across to the nearest applicable sovereign instrument named in the derivation, never an occurrence-derived number. Tin migrates from the can, so for non-canned seafood the read-across is a packaging-migration baseline that clean product clears.
Derivation
The full derivation for Freshwater fish (tilapia, catfish, trout, carp). Each row lists every government maximum level in force worldwide, converted to the as-consumed basis; the HMTc limit is the strictest of them, and the last column names which sovereign law binds. A blank cell means that government sets no limit for this analyte in this product.
| Analyte | EU | AU/NZ | GSO | India | Mercosur | Costa Rica | Fiji | Guyana | Israel | Morocco | Mexico | Panama | Philippines | Paraguay | Singapore | Thailand | Trinidad & Tobago | Uruguay | Vietnam | Hong Kong | HMTc | Binds |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lead (Pb) | 300 | 500 | 300 | 300 | 300 | 300 | 200 | 300 | 300 | 300 | 500 | 300 | 300 | 300 | 2000 | 300 | 2000 | — | 300 | 300 | 200 | Fiji |
| Inorganic arsenic (iAs) | 100 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 100 | 100 | EU |
| Total arsenic (tAs) | — | 2000 | — | 76000 | 1000 | — | — | — | 1000 | — | — | — | — | 1000 | 1000 | — | — | — | — | — | 1000 | Singapore |
| Mercury, total (tHg) | 300 | 500 | 1000 | 500 | 500 | 500 | 500 | 500 | 500 | 500 | — | 500 | — | 500 | 500 | — | — | 500 | 500 | 500 | 300 | EU |
| Methylmercury (MeHg) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | bounded&sup5; | species ≤ tHg |
| Cadmium (Cd) | — | — | 50 | 300 | 50 | 50 | 50 | 50 | 50 | 50 | 500 | 50 | — | 50 | — | 1000 | — | — | 50 | 100 | 50 | GSO |
| Nickel (Ni) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 2000² | read-across |
| Total chromium (Cr) | — | — | — | 12000 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 1000 | 1000 | Hong Kong |
| Hexavalent chromium (Cr-VI) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 10² | read-across |
| Tin (Sn) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 200000² | read-across |
| Aluminium (Al) | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | 100000² | read-across |
All values µg/kg (ppb), as-consumed basis. ² no government regulates this analyte for this exact product form: the value is a disclosed read-across from the nearest applicable government maximum, and the derivation names the instrument it comes from. It is never taken from occurrence data. After publication the standards ratchet may tighten it, using certified-lot results only. ³ not material in this matrix: measured but with no standalone number, controlled by packaging control or by the total-metal screen, not an invented value. &sup5; a toxic species governed by and bounded by its parent total (for example inorganic arsenic ≤ total arsenic): the species can never exceed the total, so the total ceiling is the species ceiling. The total metal is measured on every lot and the species is established at baseline; no separate species ceiling is published. On ongoing lots the species is speciated whenever the total exceeds its limit.
Occurrence and derivation rationale
For each analyte on the panel: what the peer-reviewed and survey literature measured in this category, cited one way to the Heavy Metal Index, and the Method v2.0 reasoning behind the certification limit — including, where no government sets a number, why the program sets one anyway. Occurrence figures are literature findings; the derivation is the certifier's.
6 studies in the certified-market pool measured lead in Fish — freshwater across 126 certified-market samples. The pooled distribution centres on a median of 219 ppb and reaches 1.4 mg/kg at the 95th percentile. Lehel 2024, Majlesi 2019, Garofalo 2025, Maikanov 2020, Majlesi 2017, Subhanullah 2024.
HMTc sets 200 ppb (regulatory-alignment): the strictest applicable government maximum level for this product form, adopted under Method v2.0 as the default certification standard. The certified-market pool's P97 is 2 mg/kg, at or above the government ceiling of 200 ppb, so the government maximum binds. Why lead is limited →
2 studies in the certified-market pool measured inorganic arsenic in Fish — freshwater across 50 certified-market samples. The pooled distribution centres on a median of 95 ppb and reaches 347 ppb at the 95th percentile. Lehel 2024, Hoy 2023.
HMTc sets 100 ppb (regulatory-alignment): the strictest applicable government maximum level for this product form, adopted under Method v2.0 as the default certification standard. The certified-market pool's P97 is 359 ppb, at or above the government ceiling of 100 ppb, so the government maximum binds. Why inorganic arsenic is limited →
4 studies in the certified-market pool measured total arsenic in Fish — freshwater across 81 certified-market samples. The pooled distribution centres on a median of 1.2 mg/kg and reaches 1.9 mg/kg at the 95th percentile. Lehel 2024, Hoy 2023, Maikanov 2020, Subhanullah 2024.
HMTc sets 1 mg/kg (regulatory-alignment): the strictest applicable government maximum level for this product form, adopted under Method v2.0 as the default certification standard. The certified-market pool's P97 is 2 mg/kg, at or above the government ceiling of 1 mg/kg, so the government maximum binds. Why total arsenic is limited →
8 studies in the certified-market pool measured total mercury in Fish — freshwater across 1407 certified-market samples. The pooled distribution centres on a median of 50 ppb and reaches 549 ppb at the 95th percentile, with a measured maximum of 650 ppb. Eaglessmith 2016, EPA 1999, Garofalo 2025, Brodziak-Dopierala 2023, Majlesi 2019, Maikanov 2020, Majlesi 2017, Lehel 2024.
HMTc sets 300 ppb (regulatory-alignment): the strictest applicable government maximum level for this product form, adopted under Method v2.0 as the default certification standard. Why total mercury is limited →
No citable primary occurrence measurement is routed to this cell in the corpus.
HMTc sets no standalone methylmercury limit for Fish — freshwater. MeHg is a component of tHg and bounded by it (MeHg <= tHg), so the tHg ceiling is the MeHg ceiling; no separate MeHg number is published. tHg is measured on every lot, and MeHg is speciated only when tHg exceeds its limit. Why methylmercury is limited →
6 studies in the certified-market pool measured cadmium in Fish — freshwater across 117 certified-market samples. The pooled distribution centres on a median of 37 ppb and reaches 163 ppb at the 95th percentile. Lehel 2024, Majlesi 2019, Garofalo 2025, Maikanov 2020, Majlesi 2017, Subhanullah 2024.
HMTc sets 50 ppb (regulatory-alignment): the strictest applicable government maximum level for this product form, adopted under Method v2.0 as the default certification standard. The certified-market pool's P97 is 547 ppb, at or above the government ceiling of 50 ppb, so the government maximum binds. Why cadmium is limited →
3 studies in the corpus measured tin in Freshwater fish (finfish) — tilapia, catfish, trout, carp (621 samples reported across those studies): Wickramaarachchige 2022, Chung 2020, Lee 2016.
HMTc sets 200 mg/kg by read-across: Tin is a can-migration analyte; no government sets a tin ML for non-canned seafood (every seafood tin ML is canned/tinplate-only). Read-across to the EU 2023/915 general canned-food inorganic-tin ML (200000) as a packaging-migration baseline; fresh/frozen fish has no tin source and passes. Canned product is certified under the canned-seafood subcategory. Why tin is limited →
Risk Flag
On the published occurrence literature to date, Freshwater fish (tilapia, catfish, trout, carp) shows no systematic gap between typical market levels and the limit — the limit being the strictest government maximum for the product (Method v2.0). Certification is decided on a product’s own tested result, not on a distribution; an individual lot or supplier can still exceed a limit.
See the cross-category summary of the ingredients that most often struggle.
Cite this standard
Pendergrass, K. (2026). Freshwater fish (tilapia, catfish, trout, carp): HMTc standard (Standard No. 10.83138/hmtc.std.6.fish-freshwater). Institute of Contaminant Standards. https://doi.org/10.83138/hmtc.std.6.fish-freshwater
© 2026 Institute of Contaminant Standards / Heavy Metal Certified. All rights reserved.
The literature baseline for every analyte is maintained independently at the Heavy Metal Index. This certification standard applies those findings; the two are kept editorially separate by design.