The 'Blue' Gene in Jack Dempseys

[flowerpower]

I know the topic has been discussed many times before but,

I have a spawning trio of blue genes, 1 male and 2 females. The male has spawned with both females and, to my knowledge, hasn't produced any blue fry.

Based on my limited understanding of genetics, I have concluded that the male does not have the recessive blue gene(homozygous BB).

If I raise the fry to maturity, and spawn them, I figure that I should get some blue fry so long as one of the females do possess the gene(heterozygous Bb).

Is this correct or is there something that I am not factoring into the equation?

Is there any chance that the trait may be expressed in subsequent parental spawns?
No right?
Only in the f1 generation?

 

[peathenster]

If you are right - that both females are BGs and the male is a regular, there's a 50% chance that the fry will be BG. If you spawn two BGs from the brood with each other you'll be getting 25% EBs, but the problem is you won't know which ones are BGs until they spawn and you grow the fry a little. Randomly picking two would give you 25% chance of getting a pair of BGs.

From what I heard it's also not ideal to inbreed these guys for too long. All in all it may be a lot easier and better if you introduce some new BG stock from a different line.

 

[flowerpower]

The trio are siblings so inbreeding is an inevitability.
I guess its possible that I need to grow the fry on for a while longer before I know for sure. So far I've only kept them around for a few weeks. Is that long enough?

 

[Toby_H]

Inbreeding is not the end of the world... but excessive inbreeding is very bad...

Blue Dempseys have already been excessively inbred so adding to this is adding to the "very bad"...

Read up on inbreeding depression for details...


'BG' x Standard does not = 50% Blue Gene... it would (theoretically) result in 25% BG / 75% standard...

Read up on Mendelian Genetics for details...


Blue offspring are often out competed by non Blue siblings. They are also hard to distinguish from non Blue siblings to new breeders. In time you will learn the subtle traits to look for and seperate them...


I think you should acquire a Blue Dempsey from an unrelated source as your females. Using a Blue will increase the percentage of Blue offspring -and- if your females are not BG, they will produce BG offspring when spawned with a Blue Dempsey...

 

[flowerpower]

If they're hard to distinguish as fry then I think I'll have another crack at it. This time I'll remove the fry and keep a close eye on them.
The trio came from Ken Davis so I'm pretty sure that one of their parents was an electric blue and the other was either a blue gene or regular. Either way its impossible to tell whether or not my fish have the gene until they spawn again.
Do we know whether the blue gene acts independently or is it triggered by another less visible gene?

 

[Toby_H]

Do we know whether the blue gene acts independently or is it triggered by another less visible gene?

It followes Mendelian Genetics...

 

[gomezladdams]

If you are spawning sibling bgjd and getting no ebjd fry Id say either
a)all the ebjd are dying young,they are more delicate than regular jd.
or b) none of your jd are carring the gene,if they are siblings if one isnt carrying the gene chances are none are.How sure are you of the source of these fish?

 

[flowerpower]

If you are spawning sibling bgjd and getting no ebjd fry Id say either
a)all the ebjd are dying young,they are more delicate than regular jd.
or b) none of your jd are carring the gene,if they are siblings if one isnt carrying the gene chances are none are.How sure are you of the source of these fish?

Not sure. Just going on what I was told. If one of the parents was blue then all of my fish should have the gene. Right? Impossible to get regular offspring unless both of the parents has at least one dominant gene to pass along?

Well, let's see what happens in the next spawn.

 

[Sprungster]

1. If you are getting 0 EBJD's in a cross of BGXBG then it is highly likely that at least one of the parents is not really BG.

2. It is not that hard to identify the EBJD fry...make sure you got proper lighting above the tank...you will see that they are golden...easy to see it even on the first day of free swimming.

 

[Toby_H]

^I've bred a bunch of them and I can't tell which ones are blue on their first day free swimming...

...and no I'm not THAT old...