Need help with fish eggs

[BigBurgassio]

Did you get the eggs hatching yet?

 

[Coryking]

Did you get the eggs hatching yet?

Sadly none of the eggs have hatched yet. Hopefully they will tomorrow.

 

[Coryking]

So I've just come back from a short holiday and found my eggs brown and mouldy. I'm assuming that they won't hatch. Does anyone know what might have happened and how to avoid it in future.

 

[Colin_T]

How old are the eggs?
Have any of them eyed up (developed to show little fish inside with big eyes)?
If the eggs are more than 4 days old and haven't shown eyes or hatched, they are probably infertile and won't hatch.

Don't have light above the hatching container because most fish from blackwater produce eggs that are photosensitive (can't tolerate light). The eggs don't need light and should not be in a brightly lit area.

There appears to be various coloured algae on the container and that is most likely blue green algae (Cyanobacteria). It will kill eggs by smothering them.

Hatching containers should not have any nutrients in until the eggs hatch, then you feed the babies or move them into a rearing container. Having fry food encourages bad bacteria and blue green algae and will result in fewer eggs hatching. You want a clean container with clean water and an airstone bubbling away gently to keep water moving around the eggs and to keep the oxygen levels up in the water.

 

[Coryking]

Thank you Colin for your response. The eggs are now ten days old. They turned a tan colour a week ago which i thought meant they were fertile. I only had that light over them to get a clear photo. I haven't feed the eggs.

 

[Colin_T]

How warm is the water?

Do any of them look like they have something growing in them (a baby fish)?

If it's been 10 days I would say they are duds. If there's none with embryos in, I would dump them.

 

[CassCats]

Sometimes that happens with first batches, it could be a number of things.



Also food for thought... Not all corydoras come from blackwater either fwiw, aenea are a little iffy because the original described aenea comes from Trinidad, the mainland ones were never fully described, other than looking "similar". These were imported originally as aenea and all crossbred into the farmed "aenea" we know of in the hobby now--which the albino form that you have was bred further from.

On one hand, the farmed "aenea" we have now is a mix of species from various habitats, not just blackwater as the continent of south america is not just blackwater. It has way more than that, and corydoras species are found from many of those different habitats.

On the other hand, if they truly turn out to be different variants of the species of aenea, then aenea itself comes from vast habitat variations anyways, so again would not be a true blackwater fish in this case.


So! If you use tannins and the eggs are still fungusing a lot, try using methylene blue instead. M blue works better on corydoras eggs from species that don't occur in blackwater. Tannins do better for blackwater corydoras though.


But, first batch of corydoras eggs often have a low success rate. That's not abnormal, it's usually a trial run anyways for the fish parents lol. So use the experience from this to try again the next round! With aenea, there will most definitely be a next round.

 

[BigBurgassio]

Would an option be to just leave the eggs and see if they hatch in the tank ? would you need caves etc for that ?

 

[BigBen1989]

The eggs looked infertile from the picture to me from the spawn. They're not usually white like that. Should take 3-5 days to hatch, although I had Weitzmani hatch at 7 days once. After 10 days with "mould" they will definitely be no good.

Best way to hatch them and avoid the fungus taking over is a small tub floating in the tank with an air stone. I add a drop of anti-fungal treatment as well. Rasing the fry is trickier, they need tiny food like baby brine shrimp or microworms.

They'll spawn again soon. A cold water change will probably get them in the mood.

Cheers

 

[Colin_T]

Would an option be to just leave the eggs and see if they hatch in the tank ? would you need caves etc for that ?

You can leave the eggs in the main tank with the other fishes but it depends on what is in the tank. Most fish, shrimp and snails will eat fish eggs. The parent fish don't normally but other fish in the tank will definitely eat them if they see them. You can reduce egg predation by feeding the adults more often (3-5 times a day).

Corydoras lay their eggs on flat surfaces like glass or plant leaves. They don't use caves for breeding.

 

[Coryking]

Sometimes that happens with first batches, it could be a number of things.



Also food for thought... Not all corydoras come from blackwater either fwiw, aenea are a little iffy because the original described aenea comes from Trinidad, the mainland ones were never fully described, other than looking "similar". These were imported originally as aenea and all crossbred into the farmed "aenea" we know of in the hobby now--which the albino form that you have was bred further from.

On one hand, the farmed "aenea" we have now is a mix of species from various habitats, not just blackwater as the continent of south america is not just blackwater. It has way more than that, and corydoras species are found from many of those different habitats.

On the other hand, if they truly turn out to be different variants of the species of aenea, then aenea itself comes from vast habitat variations anyways, so again would not be a true blackwater fish in this case.


So! If you use tannins and the eggs are still fungusing a lot, try using methylene blue instead. M blue works better on corydoras eggs from species that don't occur in blackwater. Tannins do better for blackwater corydoras though.


But, first batch of corydoras eggs often have a low success rate. That's not abnormal, it's usually a trial run anyways for the fish parents lol. So use the experience from this to try again the next round! With aenea, there will most definitely be a next round.

Thank you so much @CassCats and @AdoraBelle Dearheart for all your help. I certainly look into methylene blue for next time and will update next time round. When i get time I will look into deeper into aenea and hopefully find out more on them.

 

[Coryking]

Would an option be to just leave the eggs and see if they hatch in the tank ? would you need caves etc for that ?

I did leave some in the tank however my glass catfish ate them. If the tank was heavy planted it may work.

 

[AdoraBelle Dearheart]

Thank you so much @CassCats and @AdoraBelle Dearheart for all your help. I certainly look into methylene blue for next time and will update next time round. When i get time I will look into deeper into aenea and hopefully find out more on them.

Sorry this batch didn't work out. But yes, it happens, and if you find yourself wanting to try again, you can use several methods to try to encourage the adults to spawn. Ideally you want to condition them with good food, water changes etc, and try to time it so you have free time to monitor the eggs/newly hatched fry.

Fungus, the odd bad egg, and infertile eggs are always risks, even with MB, there's no fool proof method to avoid it, and a 100% hatch rate, or success rate raising the fry even once hatched, is rare! My first batch I was lucky to get about 18 that hatched, out of more than 200 eggs! And even then, despite constant babying, I think I only got eight of those to adulthood. I was scrambling, learning, making Heath Robinson set ups etc

The air bubbler, clean but established parent tank water & temp are pretty important.

Main thing I struggled with, even after I had nanny neocaradina shrimp, botanicals, MB etc, was trying to separate out the eggs where I could at least into smaller clumps, and picking out ones that fungused, so the fungus didn't spread to other, good eggs. That meant I was using a strong light bar, magnifying glass, syringe (without a needle) turkey baster and tweezers to examine all the eggs closely, remove any that definitely had fungus, and some that were questionable about whether they might be infertile and thus go bad, or looked like they might fungus, I moved to the other side of the container, or to a different container, from the eggs that looked more promising. Even some of the eggs I really didn't expect to hatch, did, so having an "I don't know about this one, maybe" container was useful!

The more times per day you can check the eggs and remove fungused ones, the better. I could do it 3-4 times per day sometimes and catch it early since I was caring for folks full time and in the house, but obviously most can't do that! But I'd certainly aim for a morning and night fungus check and removing fungused eggs.

The more spawns you have and try to raise, the more practice you get, then usually you get better results. I stopped after 4 batches, fourth batch was the largest yet, with around 200 hatching, nearly 100 survived to be large enough to go to the store to find new homes. There might have been more, but I had a mass die off and lost more than 100 fry very suddenly. They'd been doing well and I'd got a bit complacent with practice, and I suspect it's because while I'd added sand from the parent tank to the fry tank, that I hadn't changed that sand for a few weeks. I'd been spot cleaning the container and doing water changes, but there's something in established sand from an established, breeding, healthy tank that helps with fry survival. Healthy, but can also be unhealthy, bacteria. I think because I hadn't changed that sand, something nasty had taken root in the substrate.

I suspect that because the die offs were quick and large numbers of fry at a time over two days, then to try to solve it I took sand from my breeding colony of G.pgmeaus instead, another healthy, established cory tank, but I didn't trust the sand from the parent tank at that point, so I moved them to a tank I knew was healthy, lost a few more individuals that were already ailing, but that solved the mass die offs and saved the 90 odd that survived and carried on growing up.

So even when you think you're doing everything right, things can still go wrong, and with some practice, some basic equipment, time etc, you can for sure keep trying, and have success raising some fry, if you'd like to!

 

[Coryking]

Sorry this batch didn't work out. But yes, it happens, and if you find yourself wanting to try again, you can use several methods to try to encourage the adults to spawn. Ideally you want to condition them with good food, water changes etc, and try to time it so you have free time to monitor the eggs/newly hatched fry.

Fungus, the odd bad egg, and infertile eggs are always risks, even with MB, there's no fool proof method to avoid it, and a 100% hatch rate, or success rate raising the fry even once hatched, is rare! My first batch I was lucky to get about 18 that hatched, out of more than 200 eggs! And even then, despite constant babying, I think I only got eight of those to adulthood. I was scrambling, learning, making Heath Robinson set ups etc

The air bubbler, clean but established parent tank water & temp are pretty important.

Main thing I struggled with, even after I had nanny neocaradina shrimp, botanicals, MB etc, was trying to separate out the eggs where I could at least into smaller clumps, and picking out ones that fungused, so the fungus didn't spread to other, good eggs. That meant I was using a strong light bar, magnifying glass, syringe (without a needle) turkey baster and tweezers to examine all the eggs closely, remove any that definitely had fungus, and some that were questionable about whether they might be infertile and thus go bad, or looked like they might fungus, I moved to the other side of the container, or to a different container, from the eggs that looked more promising. Even some of the eggs I really didn't expect to hatch, did, so having an "I don't know about this one, maybe" container was useful!

The more times per day you can check the eggs and remove fungused ones, the better. I could do it 3-4 times per day sometimes and catch it early since I was caring for folks full time and in the house, but obviously most can't do that! But I'd certainly aim for a morning and night fungus check and removing fungused eggs.

The more spawns you have and try to raise, the more practice you get, then usually you get better results. I stopped after 4 batches, fourth batch was the largest yet, with around 200 hatching, nearly 100 survived to be large enough to go to the store to find new homes. There might have been more, but I had a mass die off and lost more than 100 fry very suddenly. They'd been doing well and I'd got a bit complacent with practice, and I suspect it's because while I'd added sand from the parent tank to the fry tank, that I hadn't changed that sand for a few weeks. I'd been spot cleaning the container and doing water changes, but there's something in established sand from an established, breeding, healthy tank that helps with fry survival. Healthy, but can also be unhealthy, bacteria. I think because I hadn't changed that sand, something nasty had taken root in the substrate.

I suspect that because the die offs were quick and large numbers of fry at a time over two days, then to try to solve it I took sand from my breeding colony of G.pgmeaus instead, another healthy, established cory tank, but I didn't trust the sand from the parent tank at that point, so I moved them to a tank I knew was healthy, lost a few more individuals that were already ailing, but that solved the mass die offs and saved the 90 odd that survived and carried on growing up.

So even when you think you're doing everything right, things can still go wrong, and with some practice, some basic equipment, time etc, you can for sure keep trying, and have success raising some fry, if you'd like to!

Thank you so much @AdoraBelle Dearheart for all your help. When they breed again I will certainly be using all your advice. I'll update you when then spawn again.