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Thiaminase and Fish and Seafood – Everything You Need To Know

If you are a raw feeder you’ve probably run into the topic of Thiaminase and been told: 

  1. Avoid feeding it
  2. Don’t store it next to meat
  3. If you are going to feed fish or seafood with thiaminase then you should properly cook it.  

This topic is of deep interest to me since I feed fish and seafood with every meal. And I wanted to make sure I knew what fish was safe to feed and whether or not to cook it.  

So read on to learn:

  1. If you should feed food with thiaminase?
  2. If you need to cook food with thiaminase. 
  3. How to store food with thiaminase.

It Starts Off With Thiamine

Thiamine is a vitamin (vitamin B1) is a water-soluble vitamin, and an essential dietary nutrient in dogs and cats.

Thiamine helps your dog’s body break down food and turn it into energy. It also keeps the nervous system healthy.

How often do dogs need it?  Daily

Most common source? Food sources include pork, beef, liver, beef liver, fish and seafood. In kibble, thiamenase is added as a synthetic form because it is impacted by heat.  

Thiaminase Is An Enzyme

Most enzymes (with the exception of pepsin, rennin, and trypsin) end in “ase”.  

Thiaminase is an enzyme that breaks down thiamine into two different parts and makes it biologically inactive.  

This leads to a thiamine deficiency?

Why Did Thiamine Deficiency Make The News?

Thiamine is a delicate vitamin. It is destroyed in heat. When the meat used for kibble is rendered at over 230 degrees, it degrades thiamine.  

Kibble is cooked several times so if you can imagine by the time kibble is cooked there’s hardly any thiamine left. 

And that is why kibble companies must add the thiamine back, but in a synthetic form.  

 AAFCO (2008) states “because processing may destroy up to 90% of the thiamin in the diet, allowance should be made to ensure the minimum nutrient level is met after processing”

Dr. Conor Brady notes the following recalls related to thiamin and vitamin deficiencies as follows: 

  • 2017 J.M. Smucker Company (twice). Possible low levels of thiamine (Vitamin B1)2016 Addiction Pet foods, elevated levels of Vitamin A
  • 2016 Fromm Family Foods, elevated levels of vitamin D2016 Nestlé Purina, “may not contain the recommended level of vitamins and minerals”
  • 2015 Ainsworth Pet Nutrition voluntarily recalled their cat food for “potentially elevated vitamin D levels”
  • 2014 Natura Pet recalled cat food due to vitamin insufficiency
  • 2013 Premium Edge, Diamond Naturals and 4health dry cat food formulas voluntarily recalled due to possibility of low levels of thiamine (Vitamin B1)
  • 2012 Nestlé Purina voluntarily recalls their therapeutic canned cat food due to a low level of thiamine (Vitamin B1)
  • 2011 Wellpet LLC voluntarily recalls canned cat food less than adequate levels of thiamine (vitamin B1). WellPet decided to recall “out of an abundance of caution”
  • 2010 Blue Buffalo Company recalls their dry dog food because of possible excess of vitamin D. Blue Buffalo learned of this potential condition in its products when it received reports of 36 dogs diagnosed with high Vitamin D levels after feeding on these products
  • 2010 P&G recalls canned cat foods due to low levels of thiamine (Vitamin B1)
  • 2009 Diamond Pet foods announces recall of Premium Edge Adult Cat and Premium Edge Hairball Cat Food for the potential to produce thiamine deficiency. 21 cases confirmed in cats eating this product

There’s Also A Study On Sled Dogs That Suffered When Only Fed Fish

Thiamine deficiency also made the news when we learned that sled dogs died because of it.

But one thing to note is that these sled dogs were fed an all fish diet.  So one can conclude that the problem that variety in feeding was missed.  

And if you’re a raw feeder you also know why one of the rules is to feed a wide variety of ingredients to ensure your dog gets all the nutrients they need.  

Thiamine Deficiency Happens Commonly 

Unfortunately, there aren’t any tests to quickly diagnose thiamine deficiencies.  

It’s poorly reflected in bloodwork and not regularly tested for.  

And the reason it happens more commonly than we think is that kibble has been known to not have enough thiamin (see recalls above).

Should You Feed Fish or Seafood With Thiaminase?

Sometimes I have a very long way in answering your core question.

And if you are wondering if you should feed fish with Thiaminase the answer is:

Yes. Fish is a rich source of Omega-3 and it would be a shame to not feed fish because of being scared of thiaminase destroying thiamine.  

The great news, just like heat destroys thiamine, heat destroys thiaminase.  

So you can cook thiaminase-containing fish to make it safe to feed.  

But there is some decisions you can make with seafood that are safe to feed raw.

For example, oysters can be found canned, frozen or raw. Sourcing can be difficult for a lot of people. Also some dogs cannot eat canned food due to the histamine level.

In my case, one of my dogs can only eat low histamine food. She reacts to canned oysters and raw oysters are cost prohibitive.

I can, however, find frozen oysters shipped from Korea to San Diego and although I could feed it raw, I choose to cook it or dry it because it’s come from very far away.

Fish and Seafood with Thiaminase

Freshwater fish
Family Cyprinidae (Minnows or carps):
Common bream (Abramis brama)
Central stoneroller (Campostoma anomalum)
Goldfish (Carassius auratus)
Common carp (Cyprinus carpio)
Emerald shiner (Notropis atherinoides)
Spottail shiner (Notropis hudsonius)
Rosy red, Fathead minnow (Pimephales promelas)
Olive barb (Puntius sarana)

Family Salmonidae (Salmonids):
Lake whitefish (Coregonus clupeaformis)
Round whitefish (Prosopium cylindraceum)

Family Catostomidae (Suckers):
White sucker (Catostomus commersonii)
Bigmouth buffalo (Ictiobus cyprinellus

Family Ictaluridae (North American freshwater catfishes):
Brown bullhead catfish (Ameiurus nebulosus)
Channel catfish (Ictalurus punctatus)

Other families:
Bowfin (Amia calva) – family Amiidae (Bowfins)
Burbot (Lota lota) – family Lotidae (Hakes and burbots)
White bass (Morone chrysops) – family Moronidae (Temperate basses)
Rainbow smelt (Osmerus mordax) – family Osmeridae (Smelts)
Loach, Weatherfish (Misgurnus sp.) – family Cobitidae (Loaches)

Brackish (freshwater to marine) fish

Family Clupeidae (Herrings):
Alewife (Alosa pseudoharengus)
Gizzard Shad (Dorosoma cepedianum)

Other families:
Sea lamprey (Petromyzon marinus) – family Petromyzontidae (Lampreys)
Fourhorn Sculpin (Triglopsis quadricornis) – family Cottidae (Sculpins)
Salmon (sp. indet., processed and salted, probably Oncorhynchus sp.) – family Salmonidae (Salmonids)

Marine fish

Family Engraulidae (Anchovies):
Broad-striped anchovy (Anchoa hepsetus
Californian anchovy (Engraulis mordax)
Goldspotted grenadier anchovy (Coilia dussumieri)

Family Clupeidae (Herrings):
Atlantic herring (Clupea harrengus)
Atlantik menhaden (Brevoortia tyrannus)
Gulf menhaden (Brevoortia patronus)
Razor belly sardine (Harengula jaguana)
Sauger (Harengula jaguana)

Family Scombridae (Mackerels, tunas, bonitos):
Chub mackerel (Scomber japonicus)
Skipjack tuna (Katsuwonus pelamis)
Yellowfin tuna (Neothunnus macropterus)

Family Lutjanidae (Snappers):
Green jobfish (Aprion virescens)
Ruby snapper (Etelis carbunculus)
Crimson jobfish (Pristipomoides filamentosus)

Family Carangidae (Jacks):
Giant trevally (Caranx ignobilis)
Doublespotted queenfish (Scomberoides lysan)
Bigeye scad  (Selar crumenophthalmus)

Family Mullidae (Goatfishes):
Red Sea goatfish (Mulloidichthys auriflamma)
Yellowstripe goatfish (Mulloidichthys samoensis)
Manybar goatfish (Parupeneus multifasciatus)

Other families:
American butterfish (Peprilus triacanthus) – family Stromateidae (Butterfishes)
Southern ocellated moray (Gymnothorax ocellatus) – family Muraenidae (Moray eels)
Bonefish (Albula vulpes) – family Albulidae (Bonefishes)
Milkfish (Chanos chanos) – family Chanidae (Milkfish)
Common dolphinfish (Coryphaena hippurus) – family Coryphaenidae (Dolphinfishes)
Hawaiian flagtail (Kuhlia sandvicensis) – family Kuhliidae (Aholeholes)
Black cod (sp. indet.) – family Moridae (Morid cods)
Flathead mullet (Mugil cephalus) – family Mugilidae (Mullets)
Sixfinger threadfin (Polydactylus sexfilis) – family Polynemidae (Threadfins)
Regal parrot (Scarus dubius) – family Scaridae (Parrotfishes)
Swordfish (Xiphias gladius) – family Xiphiidae (Swordfish)


Ocean quahog (Artica islandica)
Clam (Tellina spp.)
Cherrystone, Chowder, Steamer clams (family Veneridae)
Pigtoe mussel (Pleurobema cordatum)
Scallop (Pecten grandis)
Hawaiian clam (sp. indet.; extremely high in thiaminase)
Blue mussel (Mytilus galloprovincialis)

Limpet (Helcioniscus sp.)

Hawaiian flying squid (Nototodarus hawaiiensis)

Prawn, Tiger shrimp (Penaeus spp.)

Fish and Seafood Without Thiaminase

Family Centrarchidae (North American Sunfishes):
Largemouth bass (Micropterus salmoides)
Northern rock bass (Ambloplites rupestris)
Northern smallmouth bass (Micropterus dolomieu)
Blue gill (Lepomis macrochirus)
Black crappie (Pomoxis nigromaculatus)
Pumpkinseed (Lepomis gibbosus)

Family Percidae (Perches):
Yellow perch (Perca flavescens)
Walleye (Sander vitreus)

Family Salmonidae (Salmonids):
Bloater (Coregonus hoyi)
Lake trout (Salvelinus namaycush)
Rainbow trout (Oncorhynchus mykiss)

Other families:
Ayu (Plecoglossus altivelis) – family Plecoglossidae (Ayu fish)
Longnose gar (Lepisosteus osseus) – family Lepisosteidae (Gars)
Northern Pike (Esox lucius) – family Esocidae (Pikes)

Brackish (freshwater to marine) fish
Family Salmonidae (Salmonids):
Cisco, Lake herring (Coregonus artedi)
Atlantic Salmon (Salmo salar)
Coho salmon (Oncorhynchus kisutch)
Sea trout (Salmo trutta)

Other families:
Common eel (Anguilla anguilla) – family Anguillidae (True eels)
Pond smelt (Hypomesus olidus) – family Osmeridae (Smelts)

Marine fish
Family Pleuronectidae (Righteye flounders):
Winter flounder (Pseudopleuronectes americanus)
Winter flounder, Lemon sole (Pseudopleuronectes americanus)
American plaice (Hippoglossoides platessoides)
Yellowtail flounder (Limanda ferruginea)
Atlantic halibut (Hippoglossus hippoglossus)
European plaice (Pleuronectes platessa)

Family Gadidae (Cods and haddocks)
Atlantic cod (Gadus morhua)
Haddock (Melanogrammus aeglefinus)
Saithe, Pollock (Pollachius spp.)

Family Sciaenidae (Drums or croakers):
Atlantic croaker (Micropogonias undulates)
Southern kingfish (Menticirrhus americanus)
Spot croaker (Leiostomus xanthurus)
Silver seatrout (Cynoscion nothus)
Sand weakfish (Cynoscion arenarius)

Family Carangidae (Jacks):
Greater amberjack (Seriola dumerilii)
Yellowtail scad (Atule mate)
Mackerel scad (Decapterus pinnulatus)

Family Labridae (Wrasses):
Cunner (Tautogolabrus adspersus)
Tautog (Tautoga onitis)

Family Scombridae (Mackerels, tunas, bonitos):
Atlantic mackerel (Scomber scombrus)
Kawakawa (Euthynnus affinis)

Other families:
Tusk (Brosme brosme) – family Lotidae (Hakes and burbots)
Largehead hairtail (Trichiurus lepturus) – family Trichiuridae (Cutlassfishes)
Piked dogfish (Squalus acanthias) – family Squalidae (Dogfish sharks)
Hake (Urophycis spp.) – family Phycidae (Phycid hakes)
Inshore lizardfish (Synodus foetens) – family Synodontidae (Lizardfishes)
Mullet (Mugil spp.) – family Mugilidae (Mullets)
Scup, Southern porgy (Stenotomus chrysops) – family Sparidae (Porgies)
Ocean perch, redfish (Sebastes marinus) – family Sebastidae (Rockfishes)
Black seabass (Centropristis striata) – family Serranidae (Sea basses and Groupers)
Hardhead sea catfish (Ariopsis felis) – family Ariidae (Sea catfishes)
Searobin (Prionotus spp.) – family Triglidae (Searobins)
Silver hake (Merluccius bilinearis) – family Merlucciidae (Merluccid hakes)
Eyestripe surgeonfish (Acanthurus dussumieri) – family Acanthuridae (Surgeonfishes)
Atlantic blue marlin (Makaira nigricans) – family Istiophoridae (Billfishes)
Blotcheye soldierfish (Myripristis berndti) – family Holocentridae (Squirrelfishes, soldierfishes)
Glasseye (Heteropriacanthus cruentatus) – family Priacanthidae (Bigeyes or catalufas)
Great barracuda (Sphyraena barracuda) – family Sphyraenidae (Barracudas)


Cockle (Cardium spp.)

Marine shrimps (sp. indet.; Hawaii)
Portuguese crabs (sp. indet.)

Brief squid, calmar (Lolliguncula brevis)

Fish That You Can Buy But Don’t Show Up On Lists

I can very easily find Wild Canadian Capelin at my local Asian market. It’s not clear that it’s from freshwater or the ocean. Capelin is part of the smelt family.

When in doubt, simply cook the fish to be sure low and slow in a tablespoon or two of water.

What About Storing Thiaminase Containing Fish Next To Meat?

For those that store ingredients in different containers:

There’s no need to worry about storing meat and fish next to each other in the freezer. The enzyme thiaminase cannot jump from your storage container in a frozen state, to destroy the vitamin thiamine in your meat.  

For those that prep the whole meal, in one meal prep container:

Cook the thiaminase-containing fish before you put it in the container next to the meat.

Three Final Things To Remember When Putting It All Together

There’s a lot of data out there, and it can be very confusing when you read it in parts and pieces.  

So here’s a little summary for you to remember:

  1.  If you are feeding kibble, topping off meals with protein like beef, pork, or organs, like beef liver will provide your dog important nutrients, including thiamine. 
  2. You can still feed thiaminase containing fish – but you should cook it.  
  3. You don’t have to worry about your thiaminase containing fish sitting next to meat in your freezer if they are in separate containers but if it is in the same container – cook it first. 


The Role of Thiamine and Effects of Deficiency In Dogs

Thiamine Deficiency in a Team of Sled Dogs

The Effects In Freezing Rate and Storage of B Vitamins In Beef and Pork Roasts

Mechanics Studies on Thiaminase 1


Polioencephalomalacia of Dogs with Thiamine Deficiency

Thiaminase list

A degenerative encephalomyelopathy in 7 Kuvasz puppies

Thiamine Deficiency in Dogs More Common Than You Realize

Thiaminases – Cornell Article

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