Thiaminase Article

[nmonks]

Hello all,

I've talked about thiaminase a little here at TFF, but this month I had the good fortune to edit an article for the online magazine 'Conscientious Aquarist'. Among other things the article lists the foods that contain thiaminase and the foods that don't. It also outlines some of the problems caused by thiaminase.

It does seem likely that at least some of the "mystery deaths" of freshwater morays could be down to thiaminase, since the lack of thiamine apparently causes problems with marine morays. Anyway, for anyone keeping fish that feed primarily on fish or meaty foods, this article will be extremely useful.

Cheers, Neale

PS. Moderators, I hope this isn't considered "plugging" another web site; in this instance, the information presented is unique and new to the hobby, and I think that makes it a broadly useful article.

 

[andywg]

An excellent article that. Most informative, especially the list of fish which do and do not contain thiaminase.

 

[kewskills]

Neale, excellent article, many thanks for posting.

Cheers, Karl

 

[CFC]

Interesting and worrying as i use cheap frozen prawns as the main bulk of my fishes diet and feed mussels as an occasional alternative. I have recently started usig more cheap white fish (haddock and pollack) and trout as prawns have risen in price and this seems like a better diet nutrtion wise, but it makes the water stink and although there doesn't seem to be water quality issues from ammonia and nitrite stinky water cannot be good.

 

[nmonks]

When I kept a 200-gallon brackish tank, I'd feed the gar and the monos on oily fish like bits of mackerel. While incredibly messy, it never seemed to cause any water quality problems as such. What might be an issue is that the oil seals the water off from atmospheric oxygen, so unless you have lots of water turnover to break up the oil into droplets, you could have problems. In my brackish tank I had a skimmer as well as a trickle filter, so this wasn't really a problem.

My point is that oily fish, used sparingly, would be a useful addition to the diet of most predatory fish. Fish oil is very rich in vitamins, and (Atlantic) mackerel is one of the species that doesn't have thiaminase. It's cheap and widely available. I'd recommend using it just before a big water change though, so you can skim off any oil during the water change.

CFC, just like you I've been laying off prawns since reading that piece. It's a shame that mussels are on the list too, as prawns and mussels tend to be cheapest seafood for things like catfish and puffers. Coastal squid and cockles would seem to be the safer alternatives. Pollack (what we call coley in England) is widely sold and inexpensive. Though they aren't mentioned, I'd assume tilapia would be safe, being closely related to the centrarchids, which are known to be safe.

Cheers, Neale

 

[CFC]

Im lucky with the 900g that it drains from the top so the surface is always kept free of oil and floating scum and all my other tanks run on big air powered sponges which break up any oil on the top.

Squid i have tried before without much success, they don't seem to like the texture. I've recently started feeding pellets which are designed for the Halibutt farming industry as they can be bought in large sized pellets rather than the pea sized things in the aquatics trade, but they are quite oily so I've been using them very sparingly.

 

[nmonks]

CFC - One thing with squid is that it comes in different flavours. I find that the slightly slimy, soft squid rings (at least at Waitrose) isn't very popular. But the whole baby squid goes down much better. In colour the squid rings are more cream-coloured, while the baby squid is pure white.

As for fish farm pellets, I've used them a lot. Admittedly the ones for trout and salmon rather than halibut. They can be good when fresh, but I think because of their oiliness, they turn rancid if they get too warm. So after a while my fish lost interest. Anyway, it's worth mentioning they're formulated to make fish grow fast, rather than grow healthily. As you correctly say, used sparingly they're probably a very addition to the diet of pet fish, but we should warn less experienced hobbyists that they probably wouldn't make a good staple.

Cheers, Neale

Squid i have tried before without much success, they don't seem to like the texture. I've recently started feeding pellets which are designed for the Halibutt farming industry as they can be bought in large sized pellets rather than the pea sized things in the aquatics trade, but they are quite oily so I've been using them very sparingly.

 

[iSnail]

Thanks for posting this Neale. I got worried last time you mentioned thiaminase in another thread in the oddballs section. I am still worried since a couple of my dwarf puffers seem to have lost interest in bloodworms and glassworms (live and frozen). They don't look emaciated, presumably they've been munching on baby cherry shrimps and snails. It makes me wonder if they have Thiamine Deficiency Syndrome

 

[simonas]

teresting article and worrying for me as I feed my fish a varied diet yet my fire eel only takes cheap supermarket prawn!! I need to try him on something else other than that but any attempts bar earthworms have been futile

 

[beblondie]

Great article and information thanks for the link-Anne

 

[iSnail]

teresting article and worrying for me as I feed my fish a varied diet yet my fire eel only takes cheap supermarket prawn!! I need to try him on something else other than that but any attempts bar earthworms have been futile

There is not much problem with cooked prawns since Thiaminase is destroyed by the cooking.

 

[Jelly]

Great artical. Worrying as I have a number of fish that eat Mussel exclusively.

I do have a few of questions I hope you can answer?

The mussels we buy at our fish shops have been cooked to an extent to remove them from the shells so is that still an issue as thiaminase is removed by heating?

Would farmed Salmon be a problem as the artical remarks that the fish farm industry is aware of the issue and some of the statements also refer to the diet of the fish conributing to the issue?

I do also use raw king prawns, how long would I need to blanch them for to remove the Thiaminase?

Do Earthworms contain Thiaminase?

Thanks.

 

[nmonks]

Great artical. Worrying as I have a number of fish that eat Mussel exclusively.

Indeed.

The mussels we buy at our fish shops have been cooked to an extent to remove them from the shells so is that still an issue as thiaminase is removed by heating?

Both thiaminase and Vitamin B1 are broken down by heat, so it's a no-win situation. Cooking will denature enzymes, like thiaminase, as you doubtless remember from school. But it also breaks down vitamins, which is why we're always told by doctors to eat more fruit and raw vegetables.

Would farmed Salmon be a problem as the artical remarks that the fish farm industry is aware of the issue and some of the statements also refer to the diet of the fish conributing to the issue?

Farmed salmon is just as bad as wild salmon.

I do also use raw king prawns, how long would I need to blanch them for to remove the Thiaminase?

It doesn't depending on cooking, but the species of prawn. The farmed tropical prawns you get in supermarkets (tiger prawns, king prawns, etc.) are going to be Penaeus spp., and they do seem to have thiaminase. I have no information on the coldwater prawns (Atlantic prawns, brown shrimps, etc.) one way or another. But unless you can find a report to the contrary, assume they *do* contain thiaminase.

Do Earthworms contain Thiaminase?

Don't know, but would assume not, and can find nothing on Google to suggest annelids/oligochaetes contain thiaminase.

Cheers, Neale

 

[Jelly]

Thanks Neale.

I am considering the mussels have been cooked a little more from the supermarket and are actually cheaper than the pet fish shops. Along with the use of Vitamin supplients like Vitazin or inserting manufactured pellets within the mussel will probably be the better way of feeding these fish. I will be trying to use farmed trout as the fish part of there diet. Variety will be the key with as many non Thiaminase containing foods as possible to redusing the overall long term buildup and impact of the issue.

Cheers
Steve.

 

[nmonks]

Steve, you are probably quite right to use vitamin supplements. These are absolutely standard practise in reptile keeping, and very widely done with marine fish. For advanced aquarists keeping freshwater species that don't eat pellet or flake food, the use of vitamins is probably the way forward.

As with anything to do with nutrition, variety is the key. You could also try gut-loading frozen foods. For example, if you're feeding lancefish, you could ram some cichlid pellets or herbivore flake food into the mouth of the fish. With luck your predator will eat the whole thing.

While I can't prove it, my gut feeling is that at least some of the mystery deaths associated with morays, puffers and the like have more to do with malnutrition than issues with, say, egg-binding, or nitrate toxicity. (Not that I'm ruling out those latter issues, mind!)

Cheers, Neale