PlanetCatfish.com

Amiidae got me looking at these...here http://www.predatoryfishkeepers.com/for ... gariepinus

Often we get asked how fish are stripped of there eggs and mass produced etc....for those that have not seen this sort of thing this is how eggs are often fertilized in a mass production scenario.

When it comes to hybrids works the same just with two different species.

Keep in mind, we would never do this in our fish room but this is mostly done for food production for people and these farms are important ...it is also done in the ornamental trade though as well.

Not all fish have to be killed to be stripped, but apparently these african Clarias do...most North American fish (trouts, salmon etc.)can be stripped(that is lightly squeezing eggs & sperm out of males and females) without killing the fish.

Also talking to someone that has experimented with large synos they strip without killing apparently.

This terchnique is also used for carp - which survive the treatment as wel

NJ Division of Fish & Wildlife regularly breeds these species in the 2 big state hatcheries using the hand stripping method:

Esox lucius Northern Pike
Esox lucius x E. masquinongy Tiger Muskellunge/Tiger Muskie
Esox masquinongy Muskellunge
Stizostedion vitreum Walleye/Walleye Pike
Micropterus salmoides Largemouth Bass
Micropterus dolomieu Smallmouth Bass
Lepomis macrochirus Bluegill
Lepomis gibbosus Pumpkinseed Sunfish
Pomoxis nigromaculatus Black Crappie
Morone saxatilis x M. chrysops Hybrid Striped Bass
Ictalurus punctatus Channel Catfish
Ictalurus nebulosus Brown Bullhead
Salvelinus namaycush Lake Trout
Salvelinus fontinalis Brook Trout
Oncorhynchus mykiss Rainbow Trout
Salmo trutta Brown Trout

Here's a link with an overview of their trout production (which is now at the 30 year mark!): http://www.nj.gov/dep/fgw/peqart20.htm

This PDF goes into a little more detail of how they do it:
http://www.state.nj.us/dep/fgw/pdf/cwfmp/75-130.pdf

My understanding is that normally most losses are due to the hormone injection used to make the fish's gonads mature, not the stripping of eggs and milt.

Are the hormones injected directly into the gonads...or any specific body part?
Birger

It probably doesn't matter. Most hormones will usually have a great affect on the entire organism, no matter where they are injected.

The normal way is that the injected hormones are made in the pituariry (I might have misspelled this word) and in fact, quite often a pituariry extract is given. The hormones are released into the blood, and reach in a few seconds or minutes the gonads

For injection the spot will not matter that much - as the hormanes are distributed all over the body anyway.

usually injections are done in the dorsal or caudal part of the body, in the thick muscle tissue

when injecting in the organs there's too much damage caused by the needle, but injecting in the muscles is safe

same with humans; you might have a organ related disease, but they will never stick a needle in your belly; if they rupture the intestines that will kill you
same with fish.

here are some info how its done for mass production. http://www.africancatfish.com/

youtube video here https://www.youtube.com/watch?v=li-O4unFL0E