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Fish and seafood from Thailand

Plaa-mamปลาหม่ำ

Plaa-mam is freshwater fish flesh and viscera mixed with salt and a little ground roasted rice and left to ferment for about a month in the JIRCAS method. It turns blackish red, semi-solid, salty and sour. The Thai community product standard for pla mam allows cooked rice or sticky rice too and sets a pH limit of 4.6.

Fully documentedFish and seafood3 days – 30 days

Recipe

Amounts from a sourceThe JIRCAS database method (fish to salt 3:1 by weight). The community product standard sets the limits for the finished product.
Fish flesh and viscera, cleaned3 parts by weight[jircas]
Salt1 part[jircas]
Ground roasted riceA small amountThe standard also allows cooked rice or steamed sticky rice, sugar and garlic[jircas][tcps474]

Total time across the recorded steps: 3 days – 30 days

Start
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What changes: Fish flesh and viscera are cleaned

Step 1 of 4
Clean the flesh and viscera
Time
Not documented
Temperature
Not documented
Salt
None given
Acidity
Not documented
Which microbes the steps name, step by step
T. muriaticus
Lactic acid bacteria
Flavour
Not documented
Texture
Not documented
Colour
Not documented

Microbes at work in this step

Not documented for this step.

Method

Measured measured in a studySet fixed by a specification or tested recipeReported one source reports itTypical a general value, not sourced for this fermentUnconfirmed not yet checked against a source

At a glance

Plaa-mam is freshwater fish flesh and viscera mixed with salt and a little ground roasted rice and left to ferment for about a month in the JIRCAS method. It turns blackish red, semi-solid, salty and sour. The Thai community product standard for pla mam allows cooked rice or sticky rice too and sets a pH limit of 4.6. Made in 4 steps over 3 days – 30 days. The longest step, ferment, takes 3–30 days (JIRCAS 2026). Tetragenococcus muriaticus and T. halophilus, found in pla-ra, a related Thai salt-fermented freshwater fish paste with rice, where they were the common lactic acid bacteria in products with 11 % salt or more does most of the fermenting.

Key numbers
Main step3–30 daysReported[jircas]Ferment
AciditypH up to 4.6Set[tcps474]Finished plaa-mam

What makes this one different

Plaa-mam uses fish viscera as well as flesh and much more salt (3:1) than plaa-som, with only a little roasted rice.

Related ferments

Variants

  • Suphan Buri plaa-mamMade from snakehead or giant snakehead fillet only. One maker interviewed by Utsaha et al. (2025) salts the fillet at 1 kg fish to 100 g salt for 2 months in a glazed jar, washes it, drains it overnight, cuts it 1 cm thick, mixes it with roasted rice, packs it in a jar closed tight with bamboo sheath and ferments it 4 months, then mixes in pineapple pulp and ferments it 2 more months. Another maker gave 10 kg fish to 1 kg coarse salt for 4 to 5 months.

Safety

The community product standard (TCPS 474-2547) requires pH 4.6 or lower, no Salmonella in 25 g, fewer than 10 E. coli per g, no Clostridium perfringens in 0.1 g, no parasites and no preservatives or colours, and its label must carry storage and eating advice, such as keeping it cool and cooking it before eating. JIRCAS notes it is eaten raw as well as cooked. Cooking is the safer choice, though the FDA says not to rely on boiling to destroy botulinum toxin. WHO names fermented fish among foods that have carried the toxin, and the FDA says viscera left in fish keep the risk of toxin forming. The washed, rice-packed Suphan Buri variant holds far less salt than the JIRCAS mix, so it depends on reaching a pH below 4.6, where C. botulinum does not grow. Freshwater fish eaten raw can also carry liver fluke, a parasite linked to bile-duct cancer, and a review of Thai cases names fish preserved under 7 days as a likely source.

History and sources

Every number is labelled with how it is known. How this atlas is made

The Thai Industrial Standards Institute issued the community product standard for pla mam in 2004 (TCPS 474-2547). Utsaha et al. (2025) interviewed makers in Suphan Buri, who describe plaa-mam (ปลาหมำ) as local wisdom passed down from their ancestors in the Vietnamese manner, and write that the word "mam" comes from the Thai word for ferment, mak.

Starter
The sources we found do not say how its fermentation begins.
  1. [who-botulism] World Health Organization, Botulism, fact sheetgov
  2. [fda-ch13] US Food and Drug Administration, Fish and Fishery Products Hazards and Controls Guidance, Chapter 13: Clostridium botulinum Toxin Formationgov
  3. [jircas] JIRCAS, Database of Fermented Foods of Thailand, Plaa-mam, read 2026-10gov
  4. [tcps474] Thai Industrial Standards Institute 2004, Thai Community Product Standard มผช.474/2547, Pla mam (TCPS 474-2547)spec
  5. [utsaha2025] Utsaha S., Suteebut N., Peeraphatchara C., Bunyaswat J. 2025, Local wisdom of Plamam (fermented fish) production of Playuan-Plamam Community Enterprise in Suphan Buri Province, IVEC Journal (Thai)paper
  6. [marui2015] Marui J., Boulom S., Panthavee W. et al. 2015, Culture-independent bacterial community analysis of the salty-fermented fish paste products of Thailand and Laos, Biosci. Microbiota Food Health 34(2):45–52, doi:10.12938/bmfh.2014-018paper
  7. [kaewpitoon2008] Kaewpitoon N., Kaewpitoon S.J., Pengsaa P. 2008, Opisthorchiasis in Thailand, review and current status, World J. Gastroenterol. 14(15):2297–2302paper