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A number of years ago a friend who has since passed away gave me his pair of C. duplicareus. I bred them and raised a number of fry but was always disapointed with the 1 or 2 eggs that hatched in each spawning. I did raise enough to sell a few and increase the pair to a breeding group. A summer or two ago their tank that was dark and bare came down with a bacterial infection and I lost them all. This spring I discovered that I had some spread out in various other tanks and so I set them up together as a breeding group. This time I covered the bottom of the tank with a one inch layer of light brown silica sand. As before I found summer was the time they breed most and half RO water and a few alder cones was the trigger.
I find some eggs go in the mop and just as many on the glass. Much to my surprise I found that the eggs in the mop and on the glass all were coated with the sand. I was more surprised that the spawnings were all nearly a 100% hatch. The eggs from the glass as well as the mop with the eggs are placed in a gallon jar with the tanks water and placed on the cool concrete floor with an air stone. No funguscide is used.

My question is how come the hatch is suddenly so good is it the sand holding the sperm in place? That is the only thing that was done that was different. In fact they are in the same tank as before.

Could the difference be that your first generation were WC, and your second generation grown up in your local parameters?

There could be a number of factors. And perhaps you have considered these but I will throw it out there anyways.

Perhaps the male(s) are more fertile?
What about the age of the fish?
What are the water parameters in comparison from what was used before?
Are the aquariums setup differently (even if it is a minor change)?
Are the aquariums in a different location?
Are you feeding different foods to what was being offered before?
Other reasons?

Food for thought.

Jeremy

It is impossible to know why your F1's are apparently more viable but generally tank raised fish are better adapted to life in captivity and I think that is the simplest explanation
I would be happy about it since C. duplicareous in my experience with wild fish produced few viable eggs like your first group did.

jeremybasch wrote:There could be a number of factors. And perhaps you have considered these but I will throw it out there anyways.

Perhaps the male(s) are more fertile?
What about the age of the fish?
What are the water parameters in comparison from what was used before?
Are the aquariums setup differently (even if it is a minor change)?
Are the aquariums in a different location?
Are you feeding different foods to what was being offered before?
Other reasons?

Food for thought.

Jeremy

All conditions are the same except there is now sand on the bottom.

Sand on the bottom does make a big difference for many cories. They truly prefer it. It seems to make the system healthier too as more fry survive when there is sand.

At what age are your duplicareus starting to spawn? I have some in a tank with my panda cories and I am worried they may hybridize.

Shazray wrote:Sand on the bottom does make a big difference for many cories. They truly prefer it. It seems to make the system healthier too as more fry survive when there is sand.

At what age are your duplicareus starting to spawn? I have some in a tank with my panda cories and I am worried they may hybridize.

My Duplicareus spawn at a year old when they are fully grown. Most cories spawn at one year of age.