How do you castrate a fish!?

[LordyGeordie]

I read recently that in rivers where fish are stocked for anglers they sterilise the fish so they don't interfere with the native fish stocks.

I think its to stop the stocked fish (rainbow trout) breeding with the natives (brown trout) and thereby depleting the brown trout population.

Anyhow, how the the hell do you sterilise a fish, they're not all that easy to operate on, they don't make good patients.

[Chillum]

I know they can do it with shelfish, 'cause I've often had prawn balls from my local chinese.

[Rabelais]

This is normally done in one of three ways.

Producing a triploid animal, meaning the cells contain three sets of chromosomes rather than the normal two which renders the animal sterile. The production of triploids in some species is desirable as there is no loss of condition caused by the maturation processes. The process of turning fish into triploid involves either heat, cold, pressure or chemical shocks during the period just after fertilisation. The process only works on female fish; the male fish are only partially affected. The treated male fish are unable to produce sperm, but still produce testes and all the secondary sexual characteristics which accompany this. Male parent fish for eggs to be subjected to triploidy treatment are not true males, but a result of feminisation techniques which ensures that there are no male chromosomes in the parents.

The second is the feeding of high doses of 17a-methyl testosterone to young fish as they are undergoing sexual differentiation with the aim of making them sterile. This has been achieved successfully with several species. Sterile salmon still migrate to sea as normal but do not migrate back again, some rainbow trout will begin to develop gonad tissues after 2 or more years. The use of hormones in fish which are to be consumed by humans, receives a lot of consumer resistance which is why in many countries, it is not practiced.

And thirdly is good old radiation, The exposure of young fish to controlled gamma irradiation doses from a cobalt-60 source. Still very much in the experimental stages, but results indicate that there may be potential in the future for this method. The advantage of this method of sterilisation over triploidy is that it can be used on both sexes rather than just females.

[keen2learn]

Crikey, Rabelais, I'm in awe!

[eupraxia]

The second one is sort of like putting them on the pill.

[landie]

I know how you circumcise a Whale, you send foreskin divers to do it.

[Dark Angel]

with a pair of scissors like Lorena Bobbitt.