Thiaminases are enzymes that split/break down thiamine molecules  and make them inactive. Thiamine is Vitamin B1. Enzymes are proteins produced by cells of living organisms,  which can affect the regulation of the speed of certain organic reactions.
The substance thiaminase was discovered in 1932. When silver foxes (fur production) were fed daily with more than 10% raw fish the animals became paralysed. After Vitamin B1 was added to the food, the problems were over.
In general you can say that there are two types of thiaminase:

Type 1 – This is the most common form. Type 1 is a.o. found in fish, shellfish, ferns and some bacteria (including in certain intestinal bacteria of humans). This form is of interest to us.
Type 2 – Occurs in particular bacteria. I am not a dietitian or chemist or biologist, so I cannot tell you anything about this. But they seem not to be the trouble for us garter snake keepers.

Thiaminase the most active at temperatures between 30 and 40 ° C. (86 and 104 ° F.)

Vitamin B1 (thiamine), moleculair model

For the garter snake keeper it is important what you should do in order to prevent snakes to get sick by the thiaminase. Below you see the list of fish species/families do or do not contain thiaminase.

Actually it is quite simple. Heat all fish (frozen or fresh, this does not matter) about five minutes in water of about 80 ° C. and the thiaminase is inoperative. You can also add extra Vitamin B1 to the food. This is available at a pharmacy.
I used to heat the fish, but because the fish gets soft and soggy, I stopped this.
The biggest part of the fish that I feed is smelt (Osmerus eperlanus) and this contains thiaminase. Every 3th or 4th feeding I add a multivitamin on the smelt and since a few years I also add some vitamin b1 . I do not heat the smelt. Next to smelt, I also feed the snakes with pinkies (only a few times to pregnant females and to juveniles), chicken heart, chicken stomach, chicken liver, etc. If you only give thiaminase containing fish to your snakes, you run undoubtedly more risk. It may also depend on the species to which extent they are sensitive for thiaminase.

In this film you see a garter snake that presumably suffers from thiaminase in an early stadium.

If your snakes are suffering from thiaminase you see that by the following.
By the shortage of Vitamin B1 the muscles of the lower body get paralysed. At the same time the back muscles contract normal. This leads to the strange snake-movements. Sometimes a little corkscrew-like and jerky, but usually they are doing their head up high and do this too far which makes them fall over.
When you see these symptoms you need to act immediately. Injections with thiamine (Vitamin B1) usually solve the problem. Don’t experiment but go to you vet!img031
If the snake that is suffering from thiaminase still wants to eat, you can also put pure Vitamin B1 on the food. This is only useful if the symptoms are not so severe yet. Over dosage does not happen easily because the surplus Vitamin B1 is largely excreted.
You can also solve Vitamin B1 in some water and syringes it through a injection syringe with of a tube into the oesophagus of the snake.
Ask for help if you are not sure how to do these things
Then look at what you are doing wrong in terms of the food that you give.

It is absolutely vital that you are immediately going to treat it as you see signs of thiaminase in your snakes. But do not get too scared for it. It does not happens often that garter snakes get thiaminase.

The fish species listed below were examined on whether or not they contain thiaminase.
This research is not done for garter snake lovers, but for the commercial breeding of minks.
But we can also take advantage of it…

The fish species listed below do not contain Thiaminase
Scientific name Water English name
Ambloplites r. rupestris fresh Rock bass
Anguilla rostrata fresh Eel
Brosme brosme Salt Cusk or Tusk
Centropristis striatas Salt Sea bass
Christivomer n. namaycush fresh Great Lake trout
Coregonus hoyi fresh Chub
Cynoscion avenarius Salt Drum fish family
Cynoscion nothus Salt Drum fish family
Esox lucius fresh Garfish
Gadus morrhua Salt Cod
Galeichthys felis Salt Marine catfish
Hippoglossoides platesoides Salt Dab
Hippoglossus hippoglossus Salt Halibut
Huro (Micropteris) salmoides fresh Large-mouthed black bass
Hypomesus olidus fresh Pond smelt
Leiostomus xanthurus Salt Spot croaker
Lepisosteus osseus oxyurus fresh Long-nosed gar
Lepomis gibbosus fresh Pumpkin-seed sunfish
Lepomis m. macrochirus fresh Bluegill
Leucichthys artedi areturus fresh Herring
Limanda ferruginea Salt Yellow-tail flounder
Loligo brevis Salt Short-bodied Squid
Melanogrammus aeglefinus Salt Haddock
Menticirrhus americanus Salt Southern kingfish
Merluccius bilinearis Salt Silver hake
Micropogon undulatus Salt Atlantic Croaker
Micropterus d. dolomieu fresh Smallmouth bass
Mugil spec. Salt Mugilid mullets
Oncorhynchus kisutch fresh Coho salmon
Perca flavescens fresh Yellow purch
Plecoglossus altivelis fresh Ayu or sweetfish
Pollachius virens Salt Coal fish
Pomoxis nigromaculatus fresh Black crappie
Prionotus spec. Salt Searobins
Pseudopleuronectes americanus Salt Winter flounder
Pseudopleuronectes dignabilis Salt Georges bank flounder
Salmo gairdnerii irideus fresh Rainbow trout
Salmo salar fresh Salmon
Salmo trutta fario fresh Brown trout
Scomber scombrus Salt Atlantic mackerel
Sebastes marinus Salt Rose fish
Squalus acanthias Salt Spiny dogfish
Stenotomus aculeatus Salt Porgy
Stenotomus chrysops Salt Porgy
Stizostedion v. vitreum fresh Walleye
Synodus foetens Salt Inshore Lizardfish
Tautoga onitis Salt Tautog or blackfish
Tautogolabrus adspersus Salt Bergall or cunner or conner
Trichiurus lepturus Salt Largehead hairtail or beltfish
Urophycis spec. Salt Phycid hakes




The fish species listed below do contain Thiaminase
Scientific name Water English name
Abramis brama Fresh Bream
Alosa pseudoharengus Fresh Alewife
Ameiurus melas melas Fresh Black Bullhead
Amia calva Fresh Bowfin
Anchoa hepsetus Salt Broad-striped anchovy
Artica islandica Salt Artica islandica
Brevoortia patronus Salt Gulf menhaden
Brevoortia tyrannus Salt Atlantic menhaden
Campostoma anomalum pullum Fresh Central stoneroller
Carassius auratus Fresh Goldfish
Catostomus c. commersonii Fresh White Sucker
Clams Fresh freshwater mollusks
Clupea harengus Salt Herring
Coregonus clupeaformis Fresh Lake whitefish
Cyprinus carpio Fresh Common carp
Dorosoma cepedianum Fresh American gizzard shad
Engraulis mordax Salt Northern anchovy
Belone belone Salt Garfish or sea needle
Gymnothorax ocellatus Salt Caribbean ocellated moray
Harengula pensacolae Salt Scaled sardine
Ictalurus lacustris punctatus Fresh Channel catfish
Ictiobus cyprinellus Fresh Bigmouth buffalo
Lepibema chrysops Fresh White bass
Lepimbema (Morone) chrysops Fresh White bass
Lota lota Fresh Burbot
Myoxocephalus quadricornis thompsonii Fresh Giant sculpin
Notropis hudsonius Fresh Spottail shiner
Notropus atherionoides Salt Buck eye shiner
Osmerus eperlanus Salt European smelt
Osmerus mordax Salt Rainbow smelt
Petromyzon marinus (adult) Fresh Sea lamprey
Pimephales promelas Fresh Fathead minnow
Placopecten grandis Salt Giant scallop
Pluerobema cordatum Fresh Mussell or bigtoe
Poronotus triacanthus Salt Butterfish
Primephales p. promelas Fresh Fathead Minnow
Prosopium cylindraceum quadrialaterale Fresh Round Whitefish
Scomber japonicus Salt Chub mackerel
Stizostedion canadense Fresh Sauger

A usefull webpage about Thiaminase …

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