Deutsch and Hasler (1943) and Neilands 

 (1947) determined the thiaminase activity of 

 a great number of freshwater and aquatic an- 

 imals. A number of important fishes and shell- 

 fish, however, were not examined by these 

 researchers but were investigated by several 

 other researchers. The purpose of this report, 

 therefore, is to combine the listings of thiami- 

 nase activity in aquatic animals that have ap- 

 peared in the literature and also some recent 

 unpublished work at this laboratory into a 

 comprehensive list of aquatic animals that have 

 been assayed for thiaminase activity. 



Explanation of the Tables 



The list is presented in two tables: Table 1 

 presents the information for freshwater ani- 

 mals, and Table 2 presents the information for 

 marine animals. The animals are listed alpha- 

 betically by common name. The scientific name 

 is also shown for each animal; the names were 

 taken from the publication (s) cited. The sci- 

 entific names relating to the unpublished data 

 of this laboratory are from the list published 

 by the American Fisheries Society (1960). 



The part of the animal that was analyzed 

 for thiaminase is also shown in the tables. 

 Whether the whole animal or, for example, just 

 the viscera was analyzed is important; this 

 point will be further discussed later. Where 

 the source of the animal was given in the ori- 

 ginal reference, this information is also given 

 in the tables. 



DISCUSSION 



In most cases, the whole animal was analyzed 

 for the data presented in Tables 1 and 2. How- 

 ever, for some of the animals, only the viscera 

 or flesh was analyzed. Thiaminase apparently 

 concentrates in the viscera more than in any 

 other part of the animal (Lee, 1948). Some 

 researchers have found thiaminase to be pi-esent 

 in the viscera of some aquatic animals but not 

 in the flesh of that same animal. For example, 

 Neilands (1947) found that viscera of lobster 

 contained thiaminase, but the muscle did not. 

 In over 30 marine and freshwater animals 

 studied by Neilands, however, the lobster 

 proved the only example of such a relationship. 

 In other experiments by Neilands (1947) and 



by Stout, Oldfield, and Adair (1963), the ob- 

 servation was made that fish (yellow perch, 

 white perch, and hake in these experiments) 

 generally considered to be thiaminase-free 

 could be found to contain thiaminase activity 

 if the fish was captured at a time when the 

 animal it fed on was not completely digested 

 and this animal itself contained thiaminase. 



These findings are significant for several 

 reasons: (1) It is possible that some of the 

 animals listed in Tables 1 and 2 were found to 

 contain thiaminase because they were caught 

 at a time when their stomachs contained un- 

 digested, thiaminase-containing feed. Also, the 

 opposite could be true; that is, those species 

 listed as not containing thiaminase could at 

 times be found to contain thiaminase activity 

 if captured with the undigested thiaminase- 

 containing food in their stomachs. (2) The 

 findings could help to explain apparent dis- 

 crepancies that sometimes occur in regard to 

 the reported thiaminase activity of a certain 

 species. For example, burbot is listed in Table 

 1 as containing thiaminase when the animal 

 came from the Great Lakes; whereas, burbot 

 did not contain thiaminase when captured from 

 Rainy Lake, Minn. It is possible that the bur- 

 bot feeds on thiaminase-containing animals in 

 the Great Lakes; whereas, the animals avail- 

 able for food in Rainy Lake are thiaminase- 

 free. Another possibility is that the burbot 

 from the Great Lakes was captured with un- 

 digested (thiaminase-containing) food in its 

 viscera, and the burbot from Rainy Lake was 

 captured with completely digested food in its 

 viscera. 



Additional precautions that have to be con- 

 sidered in using the data presented in the tables 

 are: The data do not indicate which animals 

 have the greatest concentration of thiaminase 

 and which have lesser concentrations of the 

 enzyme. In many respects this factor may not 

 be too important, at least with present lack 

 of knowledge about threshold concentrations 

 in regard to the ability of thiaminase to impair 

 physiological activity of thiamine. In other 

 words, even a small amount of thiaminase in 

 the animal could cause concern depending on 

 the intended use of the animal. Thus, a mink 

 rancher is not likely to feed raw, thiaminase- 

 containing fish to mink even though it was 



