Cory Eggs - Fertile?

Just a quick question - is it possible or is it normal for a bronze corydorus female to lay eggs without the presence of a male? Does this ever happen?
The reason I ask is because I have just 2 bronze corydorus in a community tank with guppies. One of them is pretty large, the other one is smaller. I do not know how to sex them but I'm pretty sure the big one is female, I'm not sure about the smaller one.
A couple of months ago I found about 40 eggs laid in the glass side of the aquarium, I had not observed any spawning behaviour, having said that, I wasn't actually paying too much attention to them at that time; the first I knew was when I was cleaning the glass and there they were. I scraped them off the glass and put them in a small container floated on the water. I put a couple of drops of methylene blue in to prevent moulding. I waited over a week but absolutely nothing happened, not a single egg hatched.
A few days ago the same thing happened but there were now probably 150 eggs. Again I have scraped them off the glass and put them in a floating plastic tub with a couple of drops of methylene blue. I haven't given up hope yet but I see no signs of the eggs developing yet after 3 days.
Is it possible that my smaller fish is also a female and if so is it possible that one of them is just laying eggs without any male involvement? Has that ever happened?

 

Answer on all questions is YES.

 

DoubleDutch - Thank you for the prompt reply. I'll leave the current crop of eggs for a few more days and see what happens. I'll also try to get a few more Corys, hopefully I'll have a male and in any case a small group is far better than just two.

 

Correction on one anwer (being fertile if you've two males). That would be unlikely. I expect the smaller one to be male though.
there has been a thread some time ago about a single.Cory laying fertile eggs.
Think that was kind of strange btw

 

Yeah, get more corydoras. Males are slimmer and smaller, and have pointed fins. Females have rounded fins and are bigger and fatter. If they have eggs then they will have rounded bellies. You'll know that they are mating when they start chasing and reversing the chase and "playing". They eventually form a T shape and start fertilization. Whether they injest the sperm and force it through the gut, of if the sperm is in the water and fertilizes the eggs. No one knows. But then she clamps 3-4 eggs in her rounded fins and sticks them either on the glass or on the underside of the plant leaves. The eggs will get eaten at some point and generally won't live or survive in a community tank. They take about 4 days to hatch, and about 3-4 days to absorb their egg sacs. Then feed them micro worms or exteremely powdered flake or shrimp pellet. In about 2-3 weeks they look and behave like minI adults. When they hit about the 4-5 week mark they are fine to add to the tank. Hope any of this helps.

 

FriarThomas111 - yes, all information greatly received. Although I only have the two they are what is left of a group of seven that I had a few years ago. The largest is pretty huge and very 'chubby', I'm certain she is female, the smaller one, is far less rounded so maybe I do actually have a true pair.
It may be that there was spawning behaviour, I don't know. They are in a tank I use to grow out guppies and are not in the best location for viewing, I tend to just feed them and do water changes, I rarely get to spend time actually watching them. I haven't given up on the eggs yet although the fact that not a single egg hatched from the last clutch does make me think that maybe none of them are fertile. Time will tell.

 

My fertility rate was about 30%, so you kinda just have to get lucky. My first clutch never hatched too.

FriarThomas111 - yes, all information greatly received. Although I only have the two they are what is left of a group of seven that I had a few years ago. The largest is pretty huge and very 'chubby', I'm certain she is female, the smaller one, is far less rounded so maybe I do actually have a true pair.
It may be that there was spawning behaviour, I don't know. They are in a tank I use to grow out guppies and are not in the best location for viewing, I tend to just feed them and do water changes, I rarely get to spend time actually watching them. I haven't given up on the eggs yet although the fact that not a single egg hatched from the last clutch does make me think that maybe none of them are fertile. Time will tell.

 

Oh well, I gave them 8 days and nothing hatched, presumably they were infertile.

 

Did they change color. Some need 10 days !

Oh well, I gave them 8 days and nothing hatched, presumably they were infertile.

 

Did they change color. Some need 10 days !

No, I saw no change in them whatsoever, a few of them fungused and turned white, I removed them as I found them, the others stayed exactly the same. I even got my magnifying glass out to see if I would detect any eyeing up or similar but there was nothing at all.

 

No, I saw no change in them whatsoever, a few of them fungused and turned white, I removed them as I found them, the others stayed exactly the same. I even got my magnifying glass out to see if I would detect any eyeing up or similar but there was nothing at all.

Ok then they must have been infertile indeed.

 

So this morning I woke up and found that my bronze cory Catalina (the only cory in the tank) had laid a bunch of eggs (130 in total). I did some research, just out of curiosity because I’ve never had a fish lay eggs before, and I found another thread that said it is possible for corys to reproduce asexualy. So I did even more reseach about cory eggs and learned that they turn tan after a day or two, but I didn’t see anything about their color before then. Is there any way to know if the eggs are viable before they change color?
(that’s Catty in the background with one of the groups of eggs)

 

Where are you seeing that corydoras can reproduce asexually? I've never heard that before and I'm skeptical.

 

Corydoras reproduce with males and females. They cannot "clone" themselves as like a self-cloning crawfish. The eggs you see should be fertilized but if you scrap them off, you can use a credit card, your finger etc, you can place them hatch them yourself (there are many videos and articles you can read to see how you hatch them). When you see some of the egss going white those are dead eggs, the others are fertile and will hatch if under the right conditions.

But if you have only the one cory (I highly suggest purchasing more as they are a schooling fish), then those eggs are not fertile and will fungus and or be eaten by the cory or any other fish/snails in the aquarium.

 

Where are you seeing that corydoras can reproduce asexually? I've never heard that before and I'm skeptical.

There is a thread on this site called “Cory Female Eggs+no Male= Lots Of Fry” that mentioned it as well as another forum that I forgot the name of. I wasn’t completely sure anout it either but I wanted to check just in case.

But if you have only the one cory (I highly suggest purchasing more as they are a schooling fish), then those eggs are not fertile and will fungus and or be eaten by the cory or any other fish/snails in the aquarium.

Okie doke. How many more cory’s would you suggest I get? Is just a buddy ok or does she need a bigger group? Thanks!

 

The most common recommendation I see is 6 or more. What size is your tank and what are the other inhabitants?

 

I would agree with a group of six or more. you might be able to get away with a group of 4-5 but the bigger the group the better.

 

The most common recommendation I see is 6 or more. What size is your tank and what are the other inhabitants?

My tank is 15 gallons and I have a betta in there with her (they get along well). I used to have another cory but he died about a year ago.

Thanks y’all. I didn’t know that corys were schooling fish. I’ll make sure to get Catty some more friends next time I get tank supplies.

 

Bronze corydoras can be a little big in a 15 gallon aquarium. If you can try upgrading to a 20 long as they will do much better in that size aquairum, especially with them being a schooling fish.

 

Bronze corydoras can be a little big in a 15 gallon aquarium. If you can try upgrading to a 20 long as they will do much better in that size aquairum, especially with them being a schooling fish.

Alrighty, thanks! I’ll look into it.

 

There is a thread on this site called “Cory Female Eggs+no Male= Lots Of Fry” that mentioned it as well as another forum that I forgot the name of. I wasn’t completely sure anout it either but I wanted to check just in case.

Wow, I just checked out that thread (and the linked article) and it sounds like there actually may be a tiny chance of a cory reproducing asexually. Fascinating!

Cory Female Eggs+no Male= Lots Of Fry

Polyploidy in fishes: patterns and processes

 

Wow, I just checked out that thread (and the linked article) and it sounds like there actually may be a tiny chance of a cory reproducing asexually. Fascinating!

Cory Female Eggs+no Male= Lots Of Fry

Polyploidy in fishes: patterns and processes[/QUOTE

Yeah, it’s really cool!

 

So the eggs ended up being duds, but it was really cool (and exciting) to know that they could have been viable. Thanks for all the cory advice!

 

There is no way one Cory could lay a 130 eggs at once.....could it??? And reproduce asexually??

DoubleDutch
Coradee

What other fish are in this tank?

 

There is no way one Cory could lay a 130 eggs at once.....could it??? And reproduce asexually??

What other fish are in this tank?

I have never heard of corys being able to reproduce asexually, as for laying 130 eggs, the aenus family in particular can lay 2-300 in one spawn.

 

I have never heard of corys being able to reproduce asexually, as for laying 130 eggs, the aenus family in particular can lay 2-300 in one spawn.

Just one female? All by herself? Wow. I can't picture one female holding 100-200 eggs! Amazing!

 

My albino Cory laid about 50 eggs before quitting. I collected all of them and had 29 hatch. I’m raising my babies and have only lost 7. My pleco was sucking them through the holes in the breeder tank. I fixed that problem. Pleco was upset.

I've worked to hard on these babies to have them eat. Pleco gets a new home sunday. My brother has a bigger tank and he needs an algae eatter. Then my babies will be safe.

 

I've worked to hard on these babies to have them eat. Pleco gets a new home sunday. My brother has a bigger tank and he needs an algae eatter. Then my babies will be safe.

awww they’re so tiny and cute! How long ago did they hatch?

 

They're 2 weeks old today. Twice as big now. You can see their front fins now. At first they're a head and a wiggle. They gather around their food like little piglets and I feed them every 4 hours or so.

 

They're 2 weeks old today. Twice as big now. You can see their front fins now. At first they're a head and a wiggle. They gather around their food like little piglets and I feed them every 4 hours or so.

awww

 

awww

You should get more coty's. It's the coolest thing ever to watch them mate and lay their eggs. I filmed it but you couldn't see her laying her eggs in her back fins.

 

You should get more coty's. It's the coolest thing ever to watch them mate and lay their eggs. I filmed it but you couldn't see her laying her eggs in her back fins.

I just got two more a couple days ago. They’re still babies though.
The panda is Holmes and the pepper is Watson.

 

I just got two more a couple days ago. They’re still babies though. View attachment 523648The panda is Holmes and the pepper is Watson.

Cute. Did you get a male? Females get almost twice the size of the males. Not sure if there’s another way to sex them.

 

Cute. Did you get a male? Females get almost twice the size of the males. Not sure if there’s another way to sex them.

I have no idea. All of the corys in the store's tank were the same size so I couldn't tell the boys from the girls.

 

I have no idea. All of the corys in the store's tank were the same size so I couldn't tell the boys from the girls.

Well your chances are 50/50. But they'll make your tank prettier anyway. I've had mine almost 2 yrs. and they've only laid eggs twice. So no hurry. LOL