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I recently came across an article written by a Discus breeder who warns against feeding even frozen Tubafix worms. He says they come from raw sewage and no matter how much rising and or freezing them will eliminate them from passing on all kinds of bacteria to fish. Is this true?

120 GAL. Community Freshwater (2 huge mated angles, 2 German rams, Red tail shark, 2 Pearl Grammies, 3 Bushynose Plecos, Swordtails

110 Gal. (3 Koi Angles, 3 black marble viel tail Angles) 20 Neon tetras, 1 red tail shark, 3 clown loaches, Platys

Ah, this is a MUCH vexed question in fishkeeping, particularly among Discus keepers.

In wild settings, Tubifex do indeed live in conditions that we would consider unsanitary. The worms themselves are actually feeders upon bacteria, and have evolved to live in environments where bacteria are plentiful. Sewage outlets are a common place to find them living, but that doesn't mean to say that they ALL live in such unpleasant places. However, it DOES mean that one has to be particularly careful about the provenance of Tubifex worms.

Discus keepers and breeders tend to shun Tubifex because if the worms are carrying some pathogenic organism with them as a 'hanger on', it's quite likely to jump ship to the Discus. In the wild, discus live in an environment that is characterised by several interesting factors, namely:

• Clean water in quantity

• Low mineral content and acidic pH

• The presence of humic acids and related compounds in some abundance

These factors combine to suppress the development of quite a few pathogens (though of course, not completely). The problem is that as a consequence, Discus have evolved to develop an immune system that is in tune with this happy environment, and consequently Discus can be readily overwhelmed by any sudden appearance of even a small number of unfamiliar pathogens arising from whatever cause. Tubifex can act as a vector for some of these - Hexamita being an organism of particular concern for Discus keepers that is known to be transmissible via Tubifex.

Frozen Tubifex should, in theory, not be a problem, but in practise, they can be. This is because the definition of 'frozen' can vary according to which individuals you approach on the subject. If the Tubifex are simply subject to a temperature drop sufficient to form ice, some of the tougher pathogens can enter an encysted state to survive (which of course is something that they can do in the wild in water bodies subject to periodic freezing). If, however, the Tubifex are frozen quickly to a temperature of less than -18 degrees C, and kept there for a significant time period, the lieklihood of survival of even tough pathogens is reduced. To be absolutely certain of killing them off, however, requires that the Tubifex be frozen to a lower temperature still - something of the order of -40 degrees C. Most of us don't have access to a freezer that powerful (they tend to be specialist commerical and scientific units with the attendant expense) and so most frozen Tubifex in circulation isn't subject to that kind of treatment.

On the other hand, FREEZE DRIED Tubifex should be safe for anything. Thanks to the nature of the operation of the freeze drying process, I cannot foresee any pathogenic organism being able to survive that process, which works courtesy of a curious physical anomaly in the behaviour of water. If the Tubifex are frozen in a block at -18 degrees C, then placed in a high vacuum chamber and subjected to a very rapid pressure drop, something rather interesting happens - the water molecules in the ice undergo a process called 'sublimation', where they change straight from the solid phase to the gas phase without passing through the intermediate liquid phase. This gas is then removed by the vacuum pump. The result is that the material left behind is subject to TOTAL dessication. The mass of Tubifex worms emerging from a freeze drying unit are, in effect, an anhydrous solid. I cannot at the moment conceive of any micro-organism that can survive that process, though the example of the Tardigrade should give pause for thought - Tardigrades are animals whose survival capacity is legendary, and they have even been known to come back to life after being coated in uranium salts, placed in a high vacuum in an electron microscope and subject to an electron beam accelerated by a potential difference of a million volts - seeing those things get up and walk about after THAT treatment really makes your eyes pop out on stalks when you see it!

Some Discus owners will even err on the side of caution to the extent of not allowing their fishes to come into contact with freeze dried Tubifex just in case. However, until someone publishes evidence that there IS a fish pathogen that can survive the freeze drying process in a manner akin to a Tardigrade, I'll put myself out on a limb and state that freeze dried Tubifex SHOULD be safe.


Panda Catfish fan and keeper/breeder since Christmas 2002

Hi,
When I read your post, I did some searching on the web.
The US Government is looking into the worms as the carrier
for the Whirling Disease, where one of the symptoms is what
gives the disease its name... the fish chase their tails
much like kittens and puppies. They have found a link
between the disease and the worms.

However, I could find nothing that encouraged its use
among us. There is some question about the disease
becoming encysted and surviving the freezing cycle inside
the shell of the cyst. In short I could find nothing
that said it was safe, and much that questioned their use.
Frank


-->>> The Confidence of Amateurs, is the Envy of Professionals <<<--

Calilasseia, wow thanks so much for your indepth explaination. Frank thanks also for researching this as well. I bought some frozen ones a while ago because I remember as a kid I used to buy them live at my local (and only pet shop) They used to supply a feeding cone to put them in. Everyone I knew bought these for their fish as a treat and they loved them. We are taking about this happening (ahem) a few years ago..before computers and even any good fish books were available. Well anyway I'm throwing them out, I'm not taking any chances. By the way this whirling disease, I saw some gouramies doing this at a LFS. Will their tanks be contaminated? I buy my fish there.How common is this and can it lay dorment in their tanks even if the sick ones are taken out?

120 GAL. Community Freshwater (2 huge mated angles, 2 German rams, Red tail shark, 2 Pearl Grammies, 3 Bushynose Plecos, Swordtails

110 Gal. (3 Koi Angles, 3 black marble viel tail Angles) 20 Neon tetras, 1 red tail shark, 3 clown loaches, Platys

Cal is as usual completely right. Using live worms of almost any species carries and inherent risk of parasitation and bacterial transmission. In almost any ecosystem worms are a major carrier of problems, and even parasitic worms may carry parasites themselves, the same goes for shrimp, and snails too! Chemical pollutants however are a little harder to spot.

As a general rule though, unless your fish are obligate live feeders, always go for frozen irradiated, or freeze dried, and you can be pretty sure they are unlikely to catch anything nasty. There will always be a few spores and cysts that get through the net so to speak, even in the best quality food stocks, but by and large if you go with the bigger names in food production, youll probably be safe, or at least as safe as you can realistically be without the old paranoia setting in.

One possible solution is to set up your own Tubifex cultures.

Select a few worms, wash them thoroughly, medicate their water for 24 hours to kill off certain nasties, then introduce them to the culture.

Because Tubifex feed upon bacteria, you have to cultivate some bacteria for them to eat. Usual way of doing this is to use a small (and emphasise here small) quantity of skimmed milk powder. Alternatively, some mulm from a gravel vac operation can be used.

The one problem with cultivating Tubifex is that cultures tend to have a limited life. Which means that you have to prepare a new culture and transfer worms to that one before the old culture keels over. Basically because the artificial sludge that you have to create for them to live in becomes noxious due to anaerobic decomposition after a time, and even the Tubifex will curl up and die once a culture goes bad.

Most aquarists don't consider it worth the effort, frankly, though it's something you can embark upon if you're of an experimental frame of mind. I seem to remember my TFH back numbers having something to say on this - give me time to dig up the relevant article and see if there's anything of use there.



Panda Catfish fan and keeper/breeder since Christmas 2002

Thanks, but yuk and double yuk about cultivating them myself. My fish can do without them I'm sure!! But thanks for the info!

120 GAL. Community Freshwater (2 huge mated angles, 2 German rams, Red tail shark, 2 Pearl Grammies, 3 Bushynose Plecos, Swordtails

110 Gal. (3 Koi Angles, 3 black marble viel tail Angles) 20 Neon tetras, 1 red tail shark, 3 clown loaches, Platys

Hmm. This is a common problem that is encountered at the geomicrobiology lab i work in. How to kill the bugs. Of course, the techniques that are being used in order preserve the tubifex are really all edging towards one side of the scale, freezing processes.
Perhaps if you are really unsure about any tubifex you have and want to ensure their sterility to a high degree, perhaps then you should boil them or, preferably, microwave them. I'll be very surprised if a very high population manages to survive both a freeze/freeze-drying process AND a microwave treatment.

And Calilasseia, as far as uranium is concerned - ever heard of geobacter?