I was just going to pm YuccaPatrol, but this is info some of you might be able to use.
I'm having some trouble breeding my most recent batch of cajun dwarfs. No biggie, since in one case the loss of eggs was obviously due to overcrowding. In the second case, a female berried up in the middle of my move, so I wasn't expecting much. Just to be safe, I isolated her in a breeder, and watched the number of eggs dwindle over the next few days. When she layed them, they were the typical bluish-black color I've seen many times. They have been turning to a lighter brown and the few that remained this a.m. were an almost reddish color. I assume they are infertile, which explains why she's been eating them.
Is this a correct assumption? Last batch, the spawned fairly frequently, but I was unable to closely observe what, if any color changes occur during incubation. What have you seen, YuccaP?
Color change in cray eggs
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YuccaPatrol
- Shrimp Master
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Re: Color change in cray eggs
With the exception of one female, I have observed that my crays produce more eggs than they generally can carry through the completion of development. I now expect most females to drop about half of their eggs in the first week or so. This may be because they are not attached very well, because they are infertile, because there is not enough room under the adbomen, or for some other reason I have not considered. Eggs start out blue/black and lighten in color over time. The ones that turn orange are definitely not fertile and are discarded or eaten, so I believe you are right on that.
Fertilized eggs seem to turn somewhat brown as they develop, and become more and more transparent as the yolk is consumed and the embryo develops. If you can see some transparency, you know that development is occurring on schedule.
Eventually, you can see eye spots just before the eggs hatch. They hatch at an intermediate larval form which I want to say is the megalops form, but I have not observed them under the microscope to confirm this. They will then molt again into a juvenile form which will hang on the mother for a few more days before going off on their own.
I really want to do more to learn how to maximize the reproductive success of these, but more study is necessary. I am hoping to observe some berried females in the wild this winter and see if they carry more or less eggs than I observe in my tanks. It seems that they have a relatively low success rate for reproduction. In my tanks, I have observed that less than 25% of the eggs make it through development.
At this point, my only suggestion is to isolate females to prevent egg loss due to harrassment by "jealous" males. If you can get them isolated within the first day or two, your chances are greatly improved.
Also, don't beat yourself up if your females do have heavy losses. This may just be the way it is for these crays.
Fertilized eggs seem to turn somewhat brown as they develop, and become more and more transparent as the yolk is consumed and the embryo develops. If you can see some transparency, you know that development is occurring on schedule.
Eventually, you can see eye spots just before the eggs hatch. They hatch at an intermediate larval form which I want to say is the megalops form, but I have not observed them under the microscope to confirm this. They will then molt again into a juvenile form which will hang on the mother for a few more days before going off on their own.
I really want to do more to learn how to maximize the reproductive success of these, but more study is necessary. I am hoping to observe some berried females in the wild this winter and see if they carry more or less eggs than I observe in my tanks. It seems that they have a relatively low success rate for reproduction. In my tanks, I have observed that less than 25% of the eggs make it through development.
At this point, my only suggestion is to isolate females to prevent egg loss due to harrassment by "jealous" males. If you can get them isolated within the first day or two, your chances are greatly improved.
Also, don't beat yourself up if your females do have heavy losses. This may just be the way it is for these crays.
I've had that exp breeding these guys before, losing some eggs during the process of incubation. I was never able to see the color change before, however. A look at the female and the few remaining eggs during lunch break has me thinking that NONE of the eggs were fertile.
They've had a couple of rough weeks, so I'm not even concerned yet -I'm sure they'll breed like rats like always.
They've had a couple of rough weeks, so I'm not even concerned yet -I'm sure they'll breed like rats like always.
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YuccaPatrol
- Shrimp Master
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- Joined: Sun Mar 12, 2006 4:41 pm
- Location: Burning-Ham, Alabama
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YuccaPatrol
- Shrimp Master
- Posts: 600
- Joined: Sun Mar 12, 2006 4:41 pm
- Location: Burning-Ham, Alabama
I think I have enough photos to some of the progress of egg development
1) New eggs with a black/blue/grey coloration (depending on the lighting). Notice that they are very solid and opaque.
2) Developing eggs. Notice that there is a transparent halo around each egg indicating that the yolk is being consumed during development. The transparency will increase as the yolk is consumed.
3) Hatched intermediate stage larvae showing eye spots. Remaining yolk is the dark colored area.
1) New eggs with a black/blue/grey coloration (depending on the lighting). Notice that they are very solid and opaque.
2) Developing eggs. Notice that there is a transparent halo around each egg indicating that the yolk is being consumed during development. The transparency will increase as the yolk is consumed.
3) Hatched intermediate stage larvae showing eye spots. Remaining yolk is the dark colored area.
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Neonshrimp
- Master Shrimp Nut
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- Location: California, USA
Great pictures, you can actually see the little eyes of the hatching young in the last picture 
