RD. wrote:Thank you sir, I was hoping that you might weigh in on this topic. And I stand corrected, what I meant to ask was ........
"Is it possible that certain species of puffers are unaffected by thiaminase activity", or is this just wishful thinking?
One of the reasons I asked that question was due to a study involving catfish, and sunfish, where both were fed carp eggs (high in thiaminase content) and after 30 days only the catfish were showing signs of B1 deficiency. I haven't been able to get my hands on the actual paper (Harrington, 1954) so I don't have a lot of details beyond that.
Yes, some fish need more vitamin B1 than others. I'd expect that many catfish and herbivorous fish due to their natural diet take up comparably much vitamin B1, are used to that and thus might suffer faster from a lack of it.
RD. wrote:
Varying the diet is of course a great suggestion, except hard shelled foods such as cockles
are no where to be found in my part of the world. Getting fresh clams & mussels isn't a problem,
but I would still be freezing them to reduce potential pathogens/parasites, which brings me right back to square one. The moment those clams/mussels die & begin to decompose, the thiaminase enzyme begins to be released. Also, from what I have read in various papers & studies on this subject, freezing actually increases the concentration of thiaminase in tissue.
Sure, but the shorter they are frozen the more vitamin B1 is still contained. If fed within a few weeks quite a lot of the vitamin B1 is still there. Critical ages of frozen foods are around 6 months.
RD. wrote:
I'm curious as to what you personally feel is a high concentration of B1? (in vitamins) Which leads me to my next question, for those that use Selcon, what is the B1 content listed?
Also important is the volume of vitamin solution you add to the food. If lower concentrations are used, you just add more of it. Typical vitamin solutions for fish have about 0,5 g/l thiamin. Depending on the weight of the fish a few drops injected into the food per week should be sufficient to supply most or all of the thiamine the fish needs. Generally you would want to add about 30-60 mg of thiamin to 1 kg thiaminase containing foods in order to neutralize the effect of the thiaminase. This number was found in a study on mammals fed thiaminase containing fish. Numbers for fish nutrition are quite similar.
RD. wrote:And if supplemented when feeding shellfish such as clams, mussels, etc, would the thiaminase activity in the gut not destroy most if not all of any B1 that might be present?
Rather just some of it, than most of it.
RD. wrote:To your knowledge has anyone actually studied this, with regards to feeding fish in captivity using B1 supplements when feeding foodstuffs such as clams, mussels, prawns, etc?
Yes, there's a number of studies and books that cover this topic, most are based on empiric evidence of "no deficiency disease" in contrast to "deficiency disease" rather than measuring vitamin b1 in the tissue.
RD. wrote:For the most part it seems that one is simply advised to avoid these types of foods, which is great, except I personally don't want to be taking a dremel to my fishes teeth twice a year for the rest of its life.
I'd feed the hard shelled food items you can get, but as as part of a varied, balanced diet, and with regular vitamin additions.
Give a man a fish, and he'll eat for a day. Give a fish a man, and he'll eat for weeks.
