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I am having trouble triggering Corydoras duplicareus to spawn consistently. One of my pairs spawned twice for me but the eggs were infertile/fungused. The last spawn was over a month ago and I am not really sure what the trigger was maybe a rainstorm. I am feeding lots of blackworms and doing 50% cold water changes before storms. My well water is pH 7.4 KH - 4 and GH - 5. My water goes from 74 F to ~68 F with a cold water change. Should try going from 80 - 74 F or should I look into softer and/or more acidic water?

Pete

My Corydoras duplicareous did not respond immediately to the various tricks of the trade. In fact they spawned just before I was about to make a water change.

I don't see anything wrong with your water. I do think using the slightly higher temperature isn't a bad idea but I wouldn't give up using cool water changes as a stimulus.

I have a group of C. duplicareus that are spawning on a regular basis (once every two weeks or so). I do a weekely 50% waterchange with rainwater of 15 degrees celcius. The water in my tank is areound 25 degrees celcius.

pH is around 6,5 in my rainwater and conductivity around 60 microsiemens/cm.

I wonder that you have problems to spawn Corydoras duplicareus. It is a species that doesn't need any trigger, they spawn simultaneously. How old fish do you have? And how many fish do you have in a tank? I have a breeding group of 31 pieces in a 130-liter tank and they spawn almost uniterruptedly throughout the year. I can get as much as 400 eggs a month from them. Obviously, it's not always the same females, they usually have a 3-month's pause after a 3-month's spawning period.

Seeking a specific "trigger" is not required as cartouche pointed out. I think just good husbandry is sufficient and a clue lies within cartouche's use of a large group. I think that they spawn easier in larger groups and again per catouche, only some of the females are ripe at any given time.

Yes cartouche I wonder why I have not had many spawns as well. I have only eight fish (four wild and four tank raised). The pair that spawned were tank raised and were seperated from the rest mostly because I was concerned nonbreeding fish would eat the eggs. I think I will now put them all together and see if that helps (maybe that female is now resting). I recently read on another site that they do not tend to eat their eggs.

I have been practicing what I think is good husbandry (lots of water changes and high quality foods) for many months will only two spawns as a result. I am just trying to figure out the lack of success.

Pete

petesfish wrote:Yes cartouche I wonder why I have not had many spawns as well. I have only eight fish (four wild and four tank raised). The pair that spawned were tank raised and were seperated from the rest mostly because I was concerned nonbreeding fish would eat the eggs. I think I will now put them all together and see if that helps (maybe that female is now resting). I recently read on another site that they do not tend to eat their eggs.

I have been practicing what I think is good husbandry (lots of water changes and high quality foods) for many months will only two spawns as a result. I am just trying to figure out the lack of success.

Pete

Duplicareus don't eat their eggs. If they are really not hungry. Sterbai are much more problematic in this regard.

I would simply let the fish be (all eight together). And I would feed them well. The success must come.

Well cartouche et. al. I guess you were right! My C. Duplicareus are spawning right now! I fed lots of blackworms did two 50% within 4 four days and we had a large rainstorm the last few days.

Now once they are done should I leave the eggs in with the parents or try to hatch them seperately?

Pete

Congrats on your spawn. My Duplicareus pair have spawned four times in the past eleven days. I've been hatching out my eggs in a specimen container, with an air stone and two drops of methyene blue as an antifungal. Out of 19 eggs I've only had to fungus, and those were added to the container with virtually no metheyne blue left in it. My fry have been hatching in 5 to 6 days. I'm feeding them microworms exclusively. I've been warned by a cory breeder that baby brine can harm cory fry. He feeds his microworms for months. And he raises some beautiful cories.

Just my opinion but I don't think bbs are harmful to Cory fry per se. I do think that many of the nauplii die and spoil which results in them indirectly causing problems.

Microworms have more going for them as a Corydoras fry food because they sink to the bottom where the fry search for food and they remain alive until eaten unless you are feeding oversized portions of them.

Microworms have given me better results overall than bbs. Artemia decapsulated cysts are also a good food as soon as your fry become accustomed to eating it. It never hurts to provide diversity in any fishs'diet at any point in their life cycle.

Just my opinion but I don't think bbs are harmful to Cory fry per se. I do think that many of the nauplii die and spoil which results in them indirectly causing problems.

Microworms have more going for them as a Corydoras fry food because they sink to the bottom where the fry search for food and they remain alive until eaten unless you are feeding oversized portions of them.

Microworms have given me better results overall than bbs. Artemia decapsulated cysts are also a good food as soon as your fry become accustomed to eating it. It never hurts to provide diversity in any fishs'diet at any point in their life cycle.

I'm definetely willing to give bbs a try, but i'll probably stick with micros for the most part. I'd also like to try decapsulated eggs as well.

I quess I should also note that this is the first time I have ever spawned cories.

Then try not to get discouraged. C. duplicareous is probably not the easiest Corydoras to breed.

One of the problems I have with my group is that they came in starved, emacieated, basically barely alive. I salvaged only 8 of 12. Their experience with neglect did not prepare them to be the best stock to work with.

I have only done the best I can with them and I have yet to get very viable eggs from them.

cartouche wrote:I wonder that you have problems to spawn Corydoras duplicareus. It is a species that doesn't need any trigger, they spawn simultaneously.

When you write "they spawn simultaneously", don't you really mean a completely different word,
like "they spawn spontaneously"?
Or else I don't get any meaning from your post there.

Hi Mona,
Very astute observation you made.
Can't speak for cartouche but my C. duplicareous spawn spontaneously.

Well my group laid about 12 eggs. I put them in a container with an airstone and a few drops acriflavine. I believe about half were infertile so only six hatched. All six died within two days.

Back to drawing board.

I think I might have overdosed the acriflavine slightly but I did change some of the water in the container with tank water before they hatched. I guess this species can be a bit of a challenge.

Pete

P.S. this is the first cory I have bred as well.

mona o wrote:

cartouche wrote:I wonder that you have problems to spawn Corydoras duplicareus. It is a species that doesn't need any trigger, they spawn simultaneously.

When you write "they spawn simultaneously", don't you really mean a completely different word,
like "they spawn spontaneously"?
Or else I don't get any meaning from your post there.

Yes, you are true. They spawn spontaneously. But they also often spawn all simultaneously

As for the dying of fry, I have the same problems. I posted a thread about it one month ago. The fry are very sensitive to the presence of bacteria (or infusoria?) in water. I must now use ESHA 2000, with which I at least have 50% survival rate. And as for the desinfection of eggs, methylene blue is considerably more effective than acriflavine. But you must find the right dose. Methylene blue is sold in various solutions with different dosing.

I know there are many methods which work but I have had some success using a strong Methylene blue solution as a quick egg disinfection dip and then a weaker solution during the incubation period.
Nothing profound, just sharing one of the things I've tried.

apistomaster wrote:I know there are many methods which work but I have had some success using a strong Methylene blue solution as a quick egg disinfection dip and then a weaker solution during the incubation period.
Nothing profound, just sharing one of the things I've tried.

Methylene blue didn't work in me.