Pygmy cory infertile eggs

[tam]

I was having trouble with my pygmy corys I have four left but they seem to be doing really well now. They are plump and really enjoying a diet of micro/grindle worms once a day and bug bites once a day. Over the last 6 weeks I've caught them spawning about four times. There is one female and three males. I've managed to find 1-4 eggs each time (she seems to scatter them individually under a leaf and never on the glass or more than one in one place). I've not managed to get a single egg to hatch - they all fuzz within 24 hours and no fry have appeared in the tank.

The last spawn was Wednesday and I pulled four eggs (added a wool mop which she seems to like). This time I put them in a cup of rain water and added an alder cone. Today two have a fuzzy halo and opaque so definately no good. The other two don't look that promising either - should there be eyes showing by now - I've attached a photo.

Any ideas? I was hoping they'd populate the tank - shall I give up and just buy some more?

 

[ScareCrow]

Tannins can stain the egg and turn it that colour but if that's not staining from the tannins that egg looks fertile. They normally turn that brown colour after about a day and then hatch after about 3-4.
I can't say I've seen eyes in cory eggs before but my eye sight isn't the best.
If you're putting the eggs in a cup you'll need to provide some water movement. Otherwise they'll fungus.
Personally I normally put them in a breeder box (the rigid ziss type not the net type) and face the mesh indirectly at my filter outlet to allow some flow to pass through the breeder box. I also put a cherry shrimp in the breeder box to clean the eggs and a leaf (though alder cone will work) to add some tannins, provide a place for fry to hide and provide a place for micro organisms to populate should the fry want to eat them. The tank I put the breeder box in is 60l so I don't think the tannins from one alder cone/leaf is doing much in the form of anti bacterial/fungal.
Keep snails out as the thought of some breeders is that they eat/damage the eggs.

 

[tam]

I think its from the tannins. The other batches I stuck to the side of a hob breeder box (main tank is 75l with a airline sized feed into hob), which has some small rice fish fry and a cherry shrimp but they all fungused within 24hrs so I thought I'd try an alder in a cup to up the tanin. The main tank has some tannin, but I haven't topped up leaves recently. The hob has good circulation but not high flow. There are snails in main tank but not where I've moved the eggs.

 

[Conort2]

This time I put them in a cup of rain water and added an alder cone.

Was the cup floating in the tank?

I normally just use a Tupperware with a couple of alder cones some moss and some small Malaysian trumpet snails. I float the Tupperware in the main tank and pour out most of the water each day and replace it. I used to use an airline to provide some movement but it doesn’t seem to be needed, regular water changes seem to be enough.

Cheers

 

[tam]

Was the cup floating in the tank?

Yes pegged to the side. The room temp drops at night so I thought floating would be best. I will change out the water regularly and see if the last two do anything.

If not I think I will add to the numbers as hopefully more fish means more eggs to help the odds of them being fertile.

 

[ScareCrow]

Are they under bright light? I've heard from far more experienced breeders that it makes no difference but I believe that light does have an impact on breeding success.
My gold lasers would breed in my main tank but I'd get no fry. Since moving them to a dedicated tank that just gets indirect sun light, I get good hatch rates (approx 40 from the last spawn).

 

[Conort2]

If not I think I will add to the numbers as hopefully more fish means more eggs to help the odds of them being fertile.

This definitely helps, more males than females is always a good idea with corydoras. Adding more males to my duplicareus group helped them spawn more consistently.

My gold lasers would breed in my main tank but I'd get no fry.

I can’t get these to spawn no matter what I try.

 

[ScareCrow]

Probably should've asked before. Do you have any idea of roughly how old they are? I think the can breed fairly young 6-8months onwards but I'd imagine they wouldn't have a particularly high success rate at such a young age.

I can’t get these to spawn no matter what I try.

I can't get them to do it on demand but have had a couple of successful spawns. Before moving them, none of the eggs would survive.
I fed a lot of freeze dried tubifex, decapsulated brineshrimp, live grindal and white worms to condition them and then did cool water changes the day before it was due to rain. I did this several times over a couple of months and they ignored it. I then got a bit fed up and thought it must be because they're in my office and getting scared by my comings and goings. I then dropped the 3x daily feedings to once a day and left them over the weekend without food. One evening I went to check on them and they'd spawned so who knows

 

[tam]

Are they under bright light? I've heard from far more experienced breeders that it makes no difference but I believe that light does have an impact on breeding success.
My gold lasers would breed in my main tank but I'd get no fry. Since moving them to a dedicated tank that just gets indirect sun light, I get good hatch rates (approx 40 from the last spawn).

Not particularly high light, but the breeder box was the brighter end and there are windows opposite - the cup is very shaded. The adults are about a year old I think.

But, just checked now and one of the eggs has a tail! By torch I can't tell if it's mid hatching or just the yolk sack making it look like an egg with a tail.

If it's still kicking tomorrow I will oust the rice fish fry to the main tank and move it to the breeder box.

I top off about once a week or so with outdoor temp rain water, it's usually dropped 1.5" over the week - that seems to often set them off the next morning, but sometimes not and sometimes without too. I'm sure they have some logic they follow.

 

[tam]

Just one, but atleast now I know they can produce fertile eggs!

 

[ScareCrow]

@tam how did this one get on?

As a side note, I collected some duplicareus eggs and although they didn't feel particularly sticky. The shrimp I put in with the eggs got stuck to one almost immediately. Despite all attempts to free it, the shrimp ended up having to wait until the fry hatched before I could get the remaining bits of egg off of it's legs without damaging the shrimp.

 

[tam]

He was still kicking yesterday evening, but I was looking for him just now and can't find him so he might have popped his clogs and the shrimp cleaned up I will check again later as it's so tiny and see through it's hard to spot unless it's moving even in a 6" clear container. I did a water change yesterday so I'm hoping they might get frisky and lay some more. It's quite hard to feed just one without putting excess food in.

I guess attaching them direct to a moving shrimp is one way to achieve adaquate flow around the eggs!

 

[Conort2]

It's quite hard to feed just one without putting excess food in.

I always put quite a few snails in if I only have a few fry. They clear up all the uneaten food and also provide infusoria through their waste.

 

[ScareCrow]

I don't add snails due to the belief that they may damage eggs but within a couple of days they climb into the breeder box from the main tank. By then most of the eggs have hatched so I leave them in there to clean up any uneaten food.

 

[tam]

Thanks thanks a good idea. I've bladder snails in the main tank, but they haven't made their way into the breeder box so I will help one along.

 

[Conort2]

I don't add snails due to the belief that they may damage eggs but within a couple of days they climb into the breeder box from the main tank. By then most of the eggs have hatched so I leave them in there to clean up any uneaten food.

Malaysian trumpets are definitely safe with corydoras eggs. I haven’t tried any other species.

 

[dw1305]

Hi all,

Malaysian trumpets are definitely safe with corydoras eggs. I haven’t tried any other species.

There is a thread on PlanetCatfish <"Live tips to save cory eggs - PlanetCatfish.com">.

cheers Darrel

 

[tam]

Hi all,

There is a thread on PlanetCatfish <"Live tips to save cory eggs - PlanetCatfish.com">.

cheers Darrel

That's a really interesting thread - I like experiments with controls and testing different species of snail!

The alder cone is definately making a difference. I pulled two more eggs and both hatched in the cup of water + aldercone. I didn't add a snail as I have pond snails and it didn't seem as clear if they are a help or not. In any case the alder by itself does seem to work.

I've transfered both fry to the hob box. I think the next stage is getting the fry to grow on. They are so tiny! I can't see them unless they move. I'm feeding micro worms and powdered fry food but it's hard to tell if they are eating. There is atleast one still in there (day 3). I did add snails to the hob as clean up as suggested though.

I found a couple more eggs that are now soaking in alder tea, so hopefully I can increase the fry numbers.

I don't know if she is only laying a handful of eggs a time or has some hiding place I can't find. There is one corner she seems to prefer, but I've only ever found one on the glass and that was the other end of the tank.

 

[AlecF]

I have some elegans fry on the go. A well as an alder cone I used a couple of Jack Fruit Leaves, as well as oak or birch and I check in some floating plants and mossy plants, anything with wee critters. Quite quickly I put them into a shrimp tank. Usually they then disappear for weeks. They may reappear as fry, or not.

 

[dw1305]

Hi all,

The alder cone is definately making a difference. I pulled two more eggs and both hatched in the cup of water + aldercone.

I like Alder (Alnus spp.) "cones". <"Ian Fuller"> was the original source for using them <"with Corydoras eggs">. He (Ian) said, in the PC link

........ The original tip about using them was given to me by <"Hans-Georg Evers"> while I was visiting him in Hamburg a couple of years ago and a very valuable tip too.

I didn't add a snail as I have pond snails and it didn't seem as clear if they are a help or not.

I think if they are <"Lymnaea or Radix spp."> they will eat the eggs.

They are so tiny! I can't see them unless they move. I'm feeding micro worms and powdered fry food but it's hard to tell if they are eating.

Hopefully that should do. I've never seen any fry until they were grown enough to look like little adults, so they must find enough to eat in my tanks.

I have some elegans fry on the go. A well as an alder cone I used a couple of Jack Fruit Leaves, as well as oak or birch and I check in some floating plants and mossy plants, anything with wee critters. Quite quickly I put them into a shrimp tank. Usually they then disappear for weeks.

I think that is a plan.

cheers Darrel