08 February 2011

Crayfish chow

One of the big advantages of working with Marmorkrebs is that they are genetically identical. And yet, they vary (see also Vogt et al., 2008).

To make experimental results from different labs around the world more comparable, you would think that the right thing to do would be to try to standardize rearing conditions as much as possible. So I was very interested in Vogt’s comment in a recent paper that he has reared eight generations of Marmorkrebs solely on TetraWafer Mix. There are not too many animals that you can raise and breed on one single staple diet.

The eagle-eyed will notice no English on the label. As far as I can tell, this particular fish food isn’t available for sale in North America. At least, I can’t find it in Tetra’s U.S. product catalog. But it can be found in several online shops based in Europe, which will ship to North America. Shipping isn’t necessarily cheap, however.

I managed to get some of this, and have found it to be a nice addition to the lab. Given that we have many animals housed individually in an Aquatic Habitats system, the wafers are much easier to give to the animals through the top holes than other flake foods. And the crayfish seem to like it.


Vogt G. 2010. Suitability of the clonal marbled crayfish for biogerontological research: A review and perspective, with remarks on some further crustaceans. Biogerontology 11(6): 643-669. http://dx.doi.org/10.1007/s10522-010-9291-6

Vogt G, Huber M, Thiemann M, van den Boogaart G, Schmitz OJ, Schubart CD. 2008. Production of different phenotypes from the same genotype in the same environment by developmental variation. The Journal of Experimental Biology 211(4): 510-523. http://dx.doi.org/10.1242/jeb.008755

P.S.—Tetra, you’ve been in business like forever. Why is your US website so hard to navigate? Couldn’t you give us a simple search box?


Wolf said...

Would it not be interesting to develop a standard food as a recipe serving the real physiological needs on scientific basis instead of relying on commercial industrial stuff?

Zen said...

It would indeed be interesting. My impression is that optimizing diet is a fairly subtle task. And given that crayfish are one of the most omnivorous groups of animals that you're likely to find, it may be hard to get a noticeable payoff for the effort you'd have to put in.

Plus, Tetra and other commercial manufacturers do this kind of stuff all the time. They probably have more research and expertise on these matters than many general scientists do.

Wolf said...

Isn´t science mostly a "fairly subtle task"? ;-)

I think your opinion about what commercial producers do or not do about researching on their product quality here is quite naive.

Tetra is a leading manufacturer and "appears" very professional to consumers, but we will never know what does or probably does not happen behind closed doors...

And we will never know about a concrete recipe, just applying the same branding should not be enough for a formally pure scientific purpose.

Perhaps someday someone will manage this task...hopefully.


Zen said...

Point taken. But there’s a proverb that if the tree falls, the axe was sharp enough. That this has been used to rear multiple generations of crayfish in the lab suggests its a sharp enough axe.

Wolf said...

I got your point, too.

What I mean is that the only thing we can be sure about a particular branded food is just the branding.

The product itself cannot be compared with itsself worldwide and at all different times.

The product quality can even differ in the same country. Tetra originally comes from Germany belonging to the European Community and the legal regulations about ornamental fishfood is not so very strict.
It is different with foodfish issues.
I don´t know what it is like in the US or even Asia...

A producer could just slightly or even profoundly from my point of view change the recipe without the need of a different declaration, the legally requested declaration is just qualitatively but not exactly quantitatively .

So we cannot have a really repeatable basis.

Actually a producer still can do many things that differ between appearance and reality.

So if all scientist would have a single and reproduceable recipe for their food, as much as it can really be compared, this would be the best way for a scientific definition.

Of course if you received the same productional charge of food G√ľnther Vogt used then your crayfish keeping can be compared to his in particularly this issue for now. But what shall other scientists do?

And by the way, if we just take the product description, where is the evidence for fish and crayfish having the same needs? Or the scientific proof that this product really satisfies the needs, 8 generations only proof that they survived within relatively short reproduction cycles (but I have not read yet the article you are corresponding to)

I don´t want to annoy you, I am just questioning.

It is just a matter not to take anything for granted in science.

And especially not to believe in any commerciality.


Wolf said...

Post Scriptum:

I now just scanned the article and it says:

"Development and growth, life-span, reproduction, coloration, and
morphological characters were investigated in several batches and
monitored for a maximum of 910 days.
The only food source for all life stages
was TetraWafer Mix, which was fed once a day ad libitum."

How long is the natural maximum lifespan of a Marmorkrebs?

Wolf said...


Sorry I currently do not have the time for a better investigation, I just flew over:

Vogt G. 2010. Suitability of the clonal marbled crayfish for biogerontological research: A review and perspective, with remarks on some further crustaceans. Biogerontology 11(6): 643–669. http://dx.doi.org/10.1007/s10522-010-9291-6


from its literaturelist over:

Vogt G (2008c) Investigation of hatching and early postembryonic
life of freshwater crayfish by in vitro culture,
behavioral analysis, and light and electron microscopy. J
Morphol 269:790–811. doi:10.1002/jmor.10622

the interesting parts seem to be (apart from that Vogt apparently swears on the Wafers):

span varied between 312 and 1610 days. Earliest spawning
occurred at day 157 and latest spawning at day 1530. Note
rather constant mortality between 450 and 950 days."

"They are omnivorous
and can be fed with a single pellet food (TetraWafer
Mix) from their first feeding stage to death, which is
very exceptional in both vertebrates and invertebrates
(Vogt et al. 2004; Vogt 2008c). The pellets are
obviously a wholly adequate diet because I have kept
marbled crayfish on this food for eight generations
without loss of vitality. Clutch sizes in captivity are
comparable to those of wild population (Jones et al.
2009). The maximal age cannot be compared
between our laboratory colony and wild populations
because analyses of the age structure of wild
populations are not available as yet."

So he gives a strong indication but not a real scientific evidence, I still think it would be very interesting to research on this special issue, the nutrition itsself.