PlanetCatfish.com

Been asked a question elsewhere on how these things are produced (specifically in relation to Pangasius in this case), can anyone elaborate?

Pete

I think it is an affect of inbreeding for generations

After a few generations defects pop up. This can be albinism, extra long - or short - fins, deformed gill covers or, as stated, missing vertebrae resulting in short bodied fish.

I'm not sure, the results are too consistent, too uniform and seen in too many species for it to be selective breeding in my opinion, plus I think the producers of these fish want faster results than waiting for things like Paroon Sharks etc. to reach maturity to produce a next generation (from which they would then have to select those fish with the desirable traits, grow them on etc. etc.)

There are several methods used by laboratories and farms to force mutation. There are a handful of mutagenic chemicals used to force these in labs studying genetics, and most of the strains I'm aware of from publications, Brachydanio rerio, appear to breed true provided they are given proper care for the strain. One strain of B. rerio, commonly referred to as vampire, cannot withstand light at any stage of its life cycle.

Likewise, hyperbaric chambers are often used to force other mutations. This is most common for polyploid carp and catfish. However, there are other mutations that do show up from time to time.

I don't know if either of these are being used to produce these fish, but genetic variations have seemed to increase several fold over the past twenty years. Likewise, short-body/balloon and longfin traits showing up in so many fish in such a short time (when compared to the time a species has been kept) seems a bit odd. To think the information for using either method is readily available, and not being used by some farm somewhere, seems a bit naive to me.

Larry

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Why not ask them...

Jools

I suspect there is some way to produce some types of disabilities in fish, notably the "short body"/"balloon" shape, which does not rely on finding random mutations or inbreeding. I would guess the early stages of development is interfered with through chemicals or e.g. temperature shock. A quick google scholar search shows that treating developing zebrafish embryos with retinoic acid or methyl mercury results in animals with fused vertebrae, i.e. "balloon" shaped fish. There are, however, also mutant zebrafish in which fused vertebrae is a hereditary trait. I've never owned a "balloon" fish and never intend to, so I do not know whether the offspring of "balloon" fish are normal or have the same disability as their parents.