EBJDs – Future Project: “Green” JDs

Last updated: 2012-03-01 — Created: 2010-10-06

I’ve seen some talk of the green Jack Dempsey and some people selling these fish online. I think this would make a fascinating extension to any study of the electric blue Jack Dempsey. While I’m not anywhere near ready to undertake this endeavour, here is the theory behind it!

In addition to the wild-type and electric blue variants, there also exists a xanthistic form of the Jack Dempsey known as the gold Dempsey. The gene that causes the gold colouration is on a different locus from the gene that causes electric blue colouration, however, it is also a recessive gene. Pending the success of producing EBJDs, a logical next step might be to explore the possibilities of the “green Dempsey”, the second-generation double double-recessive gene fish that displays both the gold and electric blue traits. Doing this would require mad amounts of fishkeeping skill and patience, but would proceed as follows…

+ = wild-type gene (dominant)
b = electric blue gene (recessive)
g = gold gene (recessive) 

wild JD = +/+ +/+
BGJD    = +/b +/+
GGJD    = +/+ +/g
gold JD = +/+ g/g
EBJD    = b/b +/+
BGGG JD = +/b +/g
GG EBJD = b/b +/g
BG gold = +/b g/g

"green" JD = b/b g/g

Step 1:

Mate: (g/g +/+) to (+/+ b/b)  

  x  |  +   g  |
 b + | +/b +/g |

100% blue-gene gold-gene JDs (BGGGs)

Step 2:

Ignoring everything I said about genetic variety in other posts for simplicity’s sake, mating two of these BGGG offspring, will theoretically result in the following cross. The square gets more complicated because you are now dealing with two separate gene loci.

Mate: (+/b +/g) to (+/b +/g) 

  x  |  +   +  |  +   g  |  b   +  |  b   g  |
 + + | +/+ +/+ | +/+ +/g | +/b +/+ | +/b +/g |
 + g | +/+ +/g | +/+ g/g | +/b +/g | +/b g/g |
 b + | +/b +/+ | +/b +/g | b/b +/+ | b/b +/g |
 b g | +/b +/g | +/b g/g | b/b +/g | b/b g/g |

Result (by phenotype):
9 regular JDs
3 gold JDs
1 "green" JD

Note: The quotation marks are used very deliberately in the name “green” Jack Dempsey. The word was chosen as a reference to subtractive colour theory, where cyan (aka electric blue) and yellow (aka gold) combine to produce the colour green. The fish will not actually appear to be green in colour, but likely a paler shade of electric blue. In addition to the term “green” JD, a few other names are bouncing around, including: blue & gold JD, powder-blue JD, and platinum JD. These names all refer to the same variant of Jack Dempsey that displays both the gold and blue mutations.

March 1st, 2012 – I’ve been chatting with one of my readers, Jill, over the past several months about her work to create these “green” JDs. She has a trio of EBJDs and a trio of regular JDs she got locally, plus a breeder friend of hers was good enough to ship her a gold JD male, two unpaired BGJD females, a mated pair of BGJDs, and a number of fry from the gold male and one of the BGJD females (we think, making these fry BGGGs or GGJDs). These fry mean that Step 1 above has been skipped, kick-starting the “green” project in the middle. Step 2 was begun by growing out the fry she was given and allowing them to pair up and spawn themselves. Since these spawns were a success, there are now a number of this next generation of fry growing out.

Since Jill herself did not breed the BGGGs from a gold JD and an EBJD, we’re missing the photos of the grandparents that were used to produce the parents that were, in turn, used to produce these spawns. However, her photos do show what look to be at least three distinct phenotypes, so her results are promising so far. The hope is that both parents are BGGGs, resulting in the cross shown in Step 2 above. Should this not be the case, the EBJDs Jill’s been growing out could be used to pair with the gold male to start again from scratch, performing Step 1 herself.

Her progress can be viewed on Photobucket and YouTube. She’s also started a great thread on Monster Fish Keepers so you can watch her results unfold.

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4 Responses to EBJDs – Future Project: “Green” JDs

  1. jillfishie says:

    Hi Greg

    I’ve been busy following this project for a while now you know. I had originally bought 3 EBJDs from different pet shops to have stronger offspring. They have just now come of age & I’m ready to pair them off with some blue/gold/gene females I got along with a Gold male JD about 2 months after I got the EBJDs.

    I’m happy to say that the blue/gold/genes that I have are just now starting to pair off and the first spawn hatched Feb 02, 2012. I see some gold babies along with what look like EBJD babies & hopefully a green or two.
    I was feeding them only flake food with the parents watching over them, but yesterday after I cleaned the tank I changed their diet to frozen baby brine shrimp. I know that by using the BBS they will grow faster & I will be able to give you more info on what actually came out from this spawn. I have two other sets of fry growing out right now in 2 separate tanks. One has the spawn from my male Gold & a blue/gene female, the other has the spawn from a male blue/gene & female blue/gene. both sets of fry look normal just like wild/type. I will send you some pics as soon as I have a chance. Color patterns in the blue/genes look nice, a few dark & a lot of light colored ones. The color pattern for the gold blue/genes are nice but they are very light in color. Only about 5 in 50 have a dark color pattern. So with the new babies I have from the blue/gold mother & father I hope to get a good color pattern in the ones that aren’t Gold, EBJD or Green if I’m lucky & you’ll know what I get.
    Your blog here is the reason I started this project.
    Good luck with new Green Terrors you have coming, I’ll keep you posted in my progress here so others can see the results. I might have to Email you the pics and you post them because I’m not here very often.


  2. jillfishie says:

    Hello Greg,
    I’ve sent you a few Emails & haven’t heard back from you.

    Anyhow, I sent you a few pics of the babies. As they are starting to colour up right now.
    Whenever you get a chance you can post them here for everyone to see.

    Thank You


  3. Pingback: gold & green jack dempseys

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