Out of the Blue! Breeding the Electric Blue Jack Dempsey
Author: Harry Piken
Knowing how to get electric blue Dempseys is just the first step, and these delicate fish offer several challenges. Successfully producing blue fry tests the author’s mettle, but he finally gets the winning combination.
The Electric Blue Jack Dempsey: A Knockout Species
The electric blue Jack Dempsey is one of the most recent and spectacular genetic mutations to come into the tropical fish hobby. It is an exceptionally brilliant fish that would make a beautiful addition to any suitable tank.
Since I first set eyes on this blue morph known as the electric blue Jack Dempsey, I have been determined to breed it. I had read an earlier article in TFH detailing its origin. Several specimens had originally shown up as part of a spawn of regular Jack Dempseys. These specimens were isolated and raised to maturity, at which time they were bred.
The breeder found that while mating two blue Dempseys could produce all blue fry, they were very frail and practically impossible to raise, so he mated the blue fish to regular Jack Dempseys. This resulted in offspring that carried the blue gene, but they did not show it. We’ll call these “blue-gene” fish as opposed to visibly blue fish, also called “electric blue.” Both wild-type or “normal” Dempseys with no blue genes and “blue-gene” Dempseys with one normal gene and one blue gene are normally colored. The terminology can be a bit confusing, so please refer to the table on the following page to help you keep things straight.
In order to produce more electric blue Dempseys, these blue-gene offspring were bred to the original blue specimens. In this method, about 50 percent of the fry were blue, and 50 percent were the normal color, but since one parent was blue, all of these normal fry were blue-gene specimens.
If instead two of the normally colored specimens that were carrying the blue gene were mated to each other, this resulted in about 25 percent electric blue Jack Dempseys. I have a friend who is employing this method, but unfortunately he is not having much success—something that plagues many people working with these fish.
Visibly blue fry are weaker than normal-colored fry, whether blue-gene or pure normal, so the blue fry must be isolated as quickly as possible from their stronger, normal-colored siblings. The blue fry have an opaque coloring compared to normal-colored fish, and this difference can be detected when the fry are about a quarter of an inch in length. If the fry are not isolated when detectable, their normal-colored siblings will soon kill them.
To begin my quest to reproduce the electric blue Jack Dempsey, I had to first procure some fish that carried the blue gene. There were already many electric blues readily available in the tropical fish hobby by this time, so my first thought was to create the blue-gene Dempsey myself by breeding a male blue Jack Dempsey to a normal female Jack Dempsey. Their resulting offspring should all then carry the blue gene. After a few mismatches, I did get some blue-gene fry from one of my pairs.
I was impatient, however, and thought it would be better to get some juvenile blue-genes from a different bloodline. I was able to purchase some from an online auction. The seller was already producing a nice strain of electric blue Jack Dempseys from his efforts.
A Nice Trade
After I won the auction, I realized that I had actually met this person earlier after reading his link on Cichlid-forum.com. His name is Randy Sorenson, and he lived not too far from me in the San Diego area. I had traded some of my blue-gene Dempseys with him for some of his blues. This was before he was successfully producing an electric blue Jack Dempsey strain. Anyway, I once again drove down to his place and purchased some young electric blues and blue-gene Jack Dempseys for breeding stock.
Growth of My Jack Dempseys
I let this group grow for a few months until they were sexable. The color changes in the blue specimens were very interesting. They turned from blotched to more of a speckled blue pattern. From my experience with this fish, there are different amounts of blue coverage in mature adults, which probably depends on each specimen’s individual lineage. I have seen solid blue fish, blotched blue fish, and speckled blue fish.
The Right Couple
I raised the blue specimens separately from the blue-genes so that the electric blues could catch up in size to the blue-gene juveniles. When both groups were comparable in size, I put them all together in a 180-gallon tank.
I now had to closely study their behavior and find a mixed blue-gene/electric blue pair. It is preferable to have a male blue spawn with a female blue-gene, since males are typically stronger and more aggressive. Pairing a strong blue-gene male with a weaker electric blue female is very risky. It did not appear that I had any female electric blue Dempseys in the mix, but I had to be sure I found a definite female blue-gene in the group. Females are not too difficult to spot because they are usually smaller and have more-rounded fins. I also kept my eye on the darker blue-gene Dempseys because the females usually take on a darker color in their breeding dress and have vertical barring on their sides.
After days of observation, I zeroed in on a particular electric blue male and a blue-gene female. I was able to net out this pair and isolate them in a 20-gallon tank. Inside, I placed a PVC cave that I weighed down with rocks so it would maintain a stable position.
This pair immediately made themselves at home and began cleaning house. I knew a spawning was imminent when the female’s egglaying ovipositor tube was extended and she began cleaning the inside of the PVC cave with her mouth. The first spawn, however, was not fertile. A few weeks later there was a second spawn, and to my relief a small percentage of these eggs were fertile. I knew I finally had a fertile pair!
An Electric Success
The third spawning actually proved to be the charm. The parents were very attentive to the eggs and the hundreds of larvae. They were soon guarding a huge swarm of free-swimming fry. When the fry reached about a quarter-inch in length, I could distinguish the opaque electric blues from their brown blue-gene siblings. The electric blues also began to school separately from the blue-genes, which allowed me to divide the groups easily and place them in separate 30-gallon tanks. Soon, the brilliant iridescent blue color began to shine through on the electric blues. They started showing their color as early as about a half-inch in length. The pair has had a few more successful spawnings since then.
After much patience and trial-and-error, my breeding attempts to create my own strain of gorgeous electric blue Jack Dempseys finally brought rewards. As the saying goes, “If at first you don’t succeed, try, try again!”
[Despite prevalent thought that the blues might be hybrids, it seems clear now that they are not. We are preparing an article on the recent controversies and DNA studies of the blue Jack Dempsey to appear in a future issue of TFH. Stay tuned!—Eds.]
See the full article on TFH Digital http://www.tfhdigital.com/tfh/200811/#pg77