Cross Breeding

[africandiscus]

In “Penang Discus” (awesome book) it strongly discourages cross breeding between siblings due to very high rates of genetic disorders. How do you avoid this since batch shipments to LFS are from the same parents?

Ideally can buy from a few different LFS, but we don’t have that luxury, since no other fish shop I know of in Sydney has the same quality fish as SLS.

[dreamer]

i think its called inbreeding instead of crossbreeding...

[DiscusMan]

I asked Mr Roland Foo this very question last night.

Reference Penang Discus - Mr Shaifullah Yeng
Page 66 - Culling

My Brother in law had baby fish that looked like the ones pictured in bottom of the page with fin deformitties.

As soon as Mr yeng seen the fish he advised to seperate the parents.

Mr Foo advised that there is no chance of any genetic deformities in the F1 F2 or F3 matchings. So you can bread brother to sister three generations before you even need to worry about this problem and even after that it is like at F6 or F7 that it a 100% issue.

I would say if they breed and produce problems then split them up otherwise enjoy.

Wayne

[sunshinediscus]

When you inbreed your discus you are essentially aligning genes. This can be both a good thing and a bad thing depending on your selection skills of the brood stock and to a small degree your luck. When you breed siblings together any genes that they share will be strengthened (aligned) and passed onto the fry and with enough generations many genes will be the same and you then have what is known as a true breeding strain. For color, markings, fins and body shape etc etc the fish will begin to look very much like each other. But if you select a parent that has a flaw like a poor body shape for instance then that will also be passed on and eventually all of the fry in future generations will have a poor body shape.

When you outcross the reverse happens and a whole new set of genes are expressed among the progeny, that explains why a cross generally shows much variation in the progeny.

That explanation is very simplified and there are many factors involved. Sometimes certain charcteristics are controlled by quantative (more than one gene aligned to make a certain trait) genes (eg snakeskin genes) and no amount of inbreeding will make all the babies a snakeskin.