Advice on Corydoras eggs

[Angel-Leaf]

On Sunday I woke to find my Cory’s have laid eggs in my community tank - I have since moved them to a separate breeding box. A complete surprised as I’ve not gone out of my way to attempt breeding. Unfortunately I have no experience in recognising wether or not they are fertile. I’ll attach pictures for anyone with more experience to have a look and see if they are viable.

 

[ColdKoi]

Hard to see in those pictures but they may not be fertilized

Fertilized eggs will be clear and you should see a black spec inside. Unfertilized will be cloudy

Mine just laid eggs the other day too! Must be that time of year lol

 

[Angel-Leaf]

Hard to see in those pictures but they may not be fertilized

Fertilized eggs will be clear and you should see a black spec inside. Unfertilized will be cloudy

Mine just laid eggs the other day too! Must be that time of year lol

Ah, I did think that might be the case. Still I have them in a breeding box so I’ll wait a few more days - but I don’t expect to see any fry. - it was a surprised and tbh I’m not even sure if it’s my Albino’s or my Peppered Cory’s
, as it won’t be my Eques as they are still juveniles.

I actually think I may have triggered it by doing a deep tank clean last week, I had the heater off for a short while and after a deep substrate vacuum did my usual 50% water change. So maybe that’s why. Though it could just be the time of year perhaps… who knows.

Rambling a little, apologies, but it could be the peppered Cory’s I adopted from the returned tank at my Local store. Decided to give them a new home and they look fully mature and I’m certain one is male and the other female. My Albino’s are all quite young (under a year) and I’ve heard somewhere that’s quite young for spawning.

Anyway, thank you so much for you insight. I really appreciate it.

 

[ColdKoi]

Mine are roughly 10 months old id say and this is the first batch of eggs I’ve seen from them

I think I triggered it when I turned up the heater a hair last week which from my reading is their natural que to start ‘getting busy’ is when they see a rise in water temp after being in cooler water for a while

 

[Colin_T]

Most of the eggs appear to have something developing in them. Possibly baby albino Corydoras.

Corydoras breed after it rains, as do most freshwater fish. We used to get Cories to breed by doing huge (75-90%) daily water changes using water that is a few degrees cooler than their tank water. The sudden influx of cooler clean water simulates rainfall and stimulates the fish and they breed.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

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Edited to add a link for fry food and basic info on rearing baby fish. About 2/3s of the way down is a section called Emergency Fry Food. It's about using boiled egg yolk as a first food if you haven't got infusoria or green water for the babies.

https://www.aquariumadvice.com/forums/f82/back-to-basics-when-breeding-fish-380381.html

 

[Joe_D]

I have 4 Corys in my community tank and I appear to have some Cory eggs also..
At first I did not know what they were. Some of them are in the gravel and sort of hiding.

So, can I just leave them there and will they eventuality break down ?

 

[Colin_T]

I have 4 Corys in my community tank and I appear to have some Cory eggs also..
At first I did not know what they were. Some of them are in the gravel and sort of hiding.

So, can I just leave them there and will they eventuality break down ?

If the eggs are fertile, they should hatch within a week, usually less. If the eggs are sterile, fungus will normally grow on them and they break down. Sometimes the fish eat them too. But leave them be and see what happens.

 

[Angel-Leaf]

The eggs didn’t hatch and went utterly white. But four days later another of my females laid…so far the eggs are looking the same as the first batch. So I’m wondering if the two I thought were males might be young females instead.

I’m not intentionally breeding them anyway but it has sparked my curiosity to try and catch some eggs if I can. I’m beginning to think there is not a male among my Albino’s.

In the images are the two Albino’s I thought might be male, my females are very evidently female and very stocky.

 

[Colin_T]

Can't tell what sex they are from the pictures. To sex adult Corydoras that are in good condition, look down on them from above. Females grow bigger than males and are longer and wider than males. You might have young males that aren't sexually mature yet. Or your water could be too hard for them. Corydoras naturally occur in soft water and many soft water fishes can breed in harder water but their eggs don't develop if there are too many minerals in the water.

Contact your water supply company by website or telephone and find out what the GH and KH of the water is, and what it is measured in (ppm, dGH or something else). If they can't help you, take a glass full of tap water to a pet shop and ask them to test it for you. Write the results down in numbers at the time they do the test.

If the GH is above 250ppm, the water might be too hard for the eggs to develop.

 

[Angel-Leaf]

Can't tell what sex they are from the pictures. To sex adult Corydoras that are in good condition, look down on them from above. Females grow bigger than males and are longer and wider than males. You might have young males that aren't sexually mature yet. Or your water could be too hard for them. Corydoras naturally occur in soft water and many soft water fishes can breed in harder water but their eggs don't develop if there are too many minerals in the water.

Contact your water supply company by website or telephone and find out what the GH and KH of the water is, and what it is measured in (ppm, dGH or something else). If they can't help you, take a glass full of tap water to a pet shop and ask them to test it for you. Write the results down in numbers at the time they do the test.

If the GH is above 250ppm, the water might be too hard for the eggs to develop.

I think you’ve just solved what’s happening with regards to water hardness, my provider’s website says for my postcode area it 285 milligrammes per litre. So hard water. Perhaps that answers that.

So I wonder if you can suggest ways to help soften the water for them. I read driftwood is good for that, are there any other tricks? Not sure I want to be adding chemicals though - so as naturally as possible - even if it takes awhile.

Thanks for the advice, really appreciate it.

 

[Colin_T]

The only way to really soften water is to dilute what you have with distilled or reverse osmosis water. These types of water have little or no minerals and you mix them with the harder water to get a more desirable GH, KH and pH.

Reverse osmosis (r/o) units come in a range from portable to permanent models that are fixed in place. They have various water wastage ratios like 1:1 ratio which means you waste 1 litre of water for every litre of pure water you make. The waste water has all the minerals and stuff in it that has been removed from the clean water. Lower quality r/o units have a higher ratio with more waste water (2:1 or 3:1) meaning you get 2 or 3 litres of waste water for every 1 litre of pure water.

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Distilled water can be expensive to buy but you can make your own if you live in a warm climate.

SOLAR STILL
You can make a solar still, which works well in warm climates but not so well in cold climates. You can use them indoors in a warm room or house. It would give you pure water, no waste water and be free to make pure water, it just requires a bit of sunlight or warmth.

Get a large plastic storage container and put it outside in the sun or in a warm room.
Pour a bucket of water into the storage container.
Put a clean bucket in the middle of the storage container. Have a rock in the bucket to stop it floating around.
Put the lid on the storage container.
Put a rock or small weight on the lid in the middle, so the lid sags above the bucket.

As the sun heats up the container, water will evaporate and condense on the underside of the lid. The water will run towards the centre and drip into the bucket. When the bucket is full of water, you put it into a holding container and put the bucket back in the storage container with another bucket of tap water.

You get pure water with a pH of 7.0, 0 GH, 0KH and no wasted water, no power used and it's cheap to set up. This water can then be mixed with tap water to lower the GH, KH and pH.