Feedback on cory breeding setup/technique

[Brhino]

My first attempt at breeding C. Aeneus has ended in failure, and I'm not sure what went wrong. I thought I would share my experience here in the hopes that some experienced breeders might be able to point out mistakes I made or tell me things that I assumed were normal were not.

I have a 75g planted community tank with zebra danios, bronze corys, platies, a bristlenose pleco, a pearl gourami, red cherry shrimp, pond and assassin snails. I have only had these corys for about 2.5 months, and they have grown considerably since I got them. So, I assume they've just recently become sexually mature.

The first time I saw spawning behavior was on the morning of May 5th. I checked the tank in the morning and found the corys all chasing each other and 3 eggs on the glass. I went to tell my wife, and when I came back ~30 seconds later only one egg was left. At that point I was running late for work, and I did not have anything set up and waiting to put eggs in, so I left the remaining one there and went to work. When I came home there were no eggs to be found anywhere in the tank except for two stuck to a danio's face!

After this happened I decided to make sure I had a tank set up and waiting in case it happened again. I made sure my 10g quarantine/hospital tank was clean and filled. On the morning of May 21st I checked the tank and found a single egg on the glass. As I was looking at it one of the corys swam up and deposited several more eggs next to it. Mindful of how quickly they had gotten eaten the previous time, I immediately went to work. I rolled the eggs off of the glass with my fingertip, placing them in a tiny container. I got 8 eggs that way, leaving a couple behind. I took these to the 10g tank, and again with my finger tip I placed them on top of a plastic cave decoration (the only object in the tank) directly under the outflow of an aquaclear filter (with a sponge over the intake to prevent anything small from getting sucked up). I went back to look for more eggs but found none. Again I left for work. When I came home I saw four more eggs in the 75g, each by itself in a separate location. I did not attempt to move these, and they disappeared overnight.

The eight eggs I rescued all had an amber color, which I took as I good sign. They all stayed that way, and I did not observe any fungus or other problems. I checked them frequently and in the morning 4 days later, 5 of the eggs were gone. I scanned the tank carefully, and found several tiny objects in the tank. Some of them it was impossible to tell what they were - perhaps a hatched but dead fry, perhaps a leftover bit of egg, I wasn't sure. I did find 2 objects that definitely appeared to be "tadpole" cory fry. They did not seem to be moving but their tails were sticking out. I also found a couple objects that I believe were hydra. I've never seen those in any of my tanks before but perhaps I simply haven't been looking hard enough - if not for the fact that this was bare-bottomed tank that I was examining with my nose practically pressed against the glass I never would have seen them. I removed them.

That evening when I came home all the eggs were gone. I saw at least 5 tadpoles, some of which seemed to be moving in place, others did not. I also found more hydras, which I removed. I also saw other tiny creatures - a couple planaria, tiny snails, and critters so tiny they were simply white specs moving around.

The next day, today, the tadpoles seem to be gone. I did find two of them dead. one of those seems to be covered in fungus. The other had just a tiny bit of its egg sac remaining, and I could see it had two tiny dark dots for eyes. to be honest I'm not even positive that one's dead - I'm not sure how much movement I should expect at that stage - but it's not moving at all so I assume it is.


So, there's my story. I saved 8 eggs, they all hatched, but none lived more than a day after hatching. I'm sorry this post is so long, but I didn't want to leave anything out. If anyone has any suggestions for me, I would love to hear them.

[MatsP]

Is the water in the small tank the same as the main tank? Is the filter cycled?

I would definitely recommend using some sand on the bottom of the tank - but that probably won't fix the survival of the fry for the first couple of days - not sure what to recommend there, really.

--
Mats

[Brhino]

Yes, the water should be the same. Same source, same temperature.

The filter is something I'm a bit puzzled about. The filter's an aquaclear, and normally what I do is keep the biomedia for it inside the filter on my community tank. That keeps it populated with bacteria, so when I need to use the 10g tank for quarantine I move the biomedia in and the tank's cycled. However, eggs aren't going to generate any ammonia, and 8 cory fry in a 10 gallon tank are only going to generate an infinitesimal amount, so it seems to me that the bacteria in the media is going to starve before the fry get big enough to generate any significant bioload. Right?

[Artem]

When I bred Sterbai Corydoras I used a 2 liter ice cream container with an air stone floated in the main tank. I went a little overboard with water changes but I think this was a big key in fry survival rates. Once the fry hatched I left them to their own devices, changing water around 5-6 times a day. Once their egg sacks are consumed I put down a small layer of sand from the main tank and started lightly feeding microworms. When the fry were a week old I moved them to a 4L ice cream container with an air stone and sand, again floating in the main tank.

I would keep them in this setup for around a month feeding and doing water changes 5-6 times daily. My routine was something like 8am-12am-3pm-6pm-9pm-12pm sometimes I missed one or two. After a month I moved them to a 30L plastic tub with a cycled sponge filter and sand.

The majority of my deaths occurred while in the ice cream containers, one group of 50 died down to 10. While another group of 24 had maybe one or two deaths.

Obviously the hydras and planaria don't help - in fact the hydra might even eat the fry! But don't give up hope, its only your first time. The important thing is to learn from your mistakes.