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This problem happens when I manually hatch L397 and L134 eggs using an egg tumbler. Starting day 3 to 4 after they are being produced, some fry's yolk start to slowly burst out of the egg shell. So basically the most part of the yolk and the fry is still inside the shell but a small part is out, forming a small blob on the egg. Of course these frys die eventually.

Anyone has experienced this issue before? What could cause this and how to prevent this from happening other than just stop manually tumbling them? Thank you for any advice!

This is just an example.

What incubator are you using and how vigorous are you tumbling? The photo is too grainy to see what's happening. I suspect there is damage to membrane so you need to tumble slower - more gently. If the egg cluster is free from substrate, a simpler pipe with mesh each end and airlift to pull water through.

If you have a high number of large egg clusters an unwelling tumbler based on zoug jar design is gentler. Just circulate the egg clumps as gently - slowly as possible. Boost the dissolved oxygen level elsewhere with vigorous aeration.

Thank you very much for the suggestion. I use a Ziss egg tumbler. I actually wondered if this is caused by me tumbling the eggs too vigorously. I did try to tumble very gently and slowly. I also tried to hatch them without using an egg tumbler by just placing them in a net breeder box. The outcome is not too different. For many eggs, the membrane brakes just a little bit and a small part of the yolk leak out. The premature fry (but will survive perfectly if they break out quickly and completely) are still stuck in there. I tend to think that this may not be caused by strong tumbling, as I have not done that. For me this problem has only happened to L397 and L134 eggs, but i have not seen this in L471 and bristlenose eggs.

aquaholic wrote: ↑14 Jun 2023, 08:29 What incubator are you using and how vigorous are you tumbling? The photo is too grainy to see what's happening. I suspect there is damage to membrane so you need to tumble slower - more gently. If the egg cluster is free from substrate, a simpler pipe with mesh each end and airlift to pull water through.

If you have a high number of large egg clusters an unwelling tumbler based on zoug jar design is gentler. Just circulate the egg clumps as gently - slowly as possible. Boost the dissolved oxygen level elsewhere with vigorous aeration.

My mind goes to this being something to do with your water chemistry, such as water is too hard and them not being able to hatch properly.

I occasionally get a larger size fish egg embryo - like arowana or frontosa - sticking to outer membrane if not rotated often enough (much like a bird egg needs to be turned at least once per day) but yours are sticky adhesive eggs that don't require rotation. Too rough rotation will also bruise eggs as well.

Perhaps you should try a mucg gentler water flow that doesn't move the eggs? It's clean oxygenated water thats needed, not tumbling for this type of egg. I usually use an airlift pipe to accurately control the flow rate. For giant gourami (floating oil globule eggs) I isolate inside a plastic flower pot protruding above water level which a very strong air stone outside to create highly oxygenated water and a quiet still water zone. - water diffuses through the drainage holes at bottom. With careful frequent examination of eggs, you should see embryo development occurring and with a little more experience, you will see when this starts to go off track and adjust accordingly before more eggs are lost. Make sure to keep eggs out of light naturally.

A net breeder box is far too rough.
Try a deep ceramic or glass bowl. Or perhaps a large rounded bottom wine glass if egg mass is small, completely underwater to contain eggs with a clothes peg to secure an airstone slightly above the egg mass. You don't want these eggs moving about. The open top allows you to pipette out any dead eggs easily.

I use a pipe airlift as all your doing is pulling oxygenated water past but the bowl is easier to observe. Developing eggs require lots of oxygen demand, especially those deeper in the egg mass.

Thanks for these great suggestions. I will explore more and see if there is any improvement via using different methods.
One thing that I know for sure is that this problem only happens in L397 and L134 eggs. I also have L519s and L471s, and their eggs are smaller and i have not seen any issues tumbling them.

aquaholic wrote: ↑15 Jun 2023, 07:36 A net breeder box is far too rough.
Try a deep ceramic or glass bowl. Or perhaps a large rounded bottom wine glass if egg mass is small, completely underwater to contain eggs with a clothes peg to secure an airstone slightly above the egg mass. You don't want these eggs moving about. The open top allows you to pipette out any dead eggs easily.

I use a pipe airlift as all your doing is pulling oxygenated water past but the bowl is easier to observe. Developing eggs require lots of oxygen demand, especially those deeper in the egg mass.

Thanks for the insight! i actually thought it might be the opposite.

characinkid wrote: ↑14 Jun 2023, 19:04 My mind goes to this being something to do with your water chemistry, such as water is too hard and them not being able to hatch properly.

nabulus wrote: ↑21 Jun 2023, 05:23 Thanks for the insight! i actually thought it might be the opposite.

characinkid wrote: ↑14 Jun 2023, 19:04 My mind goes to this being something to do with your water chemistry, such as water is too hard and them not being able to hatch properly.

Here the question is, what is hard ater and what does it do?

Waterhardness refers to the concentration of calcium and magnesium ions. These are two of the more common positive ions, but sodium is much more common. And not reflected in hardness.

Still, in most natural cases, if the hardness is low, there is also not much sodium.

We used to wirk with hardness, but because of sodium it is better to use conductivity. I understand the total solids content, often referred to on this site, is also measured this way.

This technique does not measure not charged dissolved solids, such as sugar, but these concentrations are most often low. Still, in black water quite a lot of humus can be dissolved

But, what does hardness, or a high concentration of dissolved molecules or ions, do? They increase the osmotic pressure. A misleading term, unfortunately, as it is more a sucking power.

High concentrations suck water from lower concentrations - the result will be that in the end the differences in concentration are lower.

Back to fish eggs - eggs intended for soft water, such as amazonian plecos, will not explode in hard water, they will loose their water. But eggs from seafish will explode in this water.

If we look more closely, the eggs will have a similar concentration of salts, around a third of the cncentration of sea water, but an egg from a soft water fish will constanly be pumping out water - to compensate for the water sucked in by the high concedntration of salts. A sea fish on the other hand - these eggs are sucked dry and they will have to pump water in.

Pumping water in. while the egg is also sucking water itself - that will result in a blown up egg which could burst.

Not a pleco egg in hard water.

Therefore, the bursted pleco egg needs another explanation

If the adult fish are successfully hatching their eggs naturally, it's not a water chemistry issue.

Unfortunately it's all human technique error/ignorance but that's how we improve. Insufficient dissolved oxygen and mechanical abrasion would be my starting points to eliminate.

True. For me the problem seems to only happen when I manually hatch them. There have been mainly two issues: 1. Permatured, broken, egg shell as described in here; and 2. some fry have trouble to absorb the yolk completely. When I let the male take care of the babies, I did not see either happened.
The same issues happen to L397 too. But, for me this problem did not happen to L471 and L519 and their egg size is much smaller.
I will definitely be more careful when hatching them using an egg tumbler. Thanks again for the advice.

aquaholic wrote: ↑22 Jun 2023, 02:54 If the adult fish are successfully hatching their eggs naturally, it's not a water chemistry issue.

Unfortunately it's all human technique error/ignorance but that's how we improve. Insufficient dissolved oxygen and mechanical abrasion would be my starting points to eliminate.

Thank you again for sharing your thoughts with me! I am monitoring the water hardness. GH is near 0. This is measured by a aquarium coop muti-test strip. Not sure how accurate it is. Nevertheless for L134 and L397, I think I will mainly rely on the male to hatch the eggs. For the plecos with smaller eggs I feel an egg tumbler is safe. Never had issues with the latter.




[/quote]

Here the question is, what is hard ater and what does it do?

Waterhardness refers to the concentration of calcium and magnesium ions. These are two of the more common positive ions, but sodium is much more common. And not reflected in hardness.

Still, in most natural cases, if the hardness is low, there is also not much sodium.

We used to wirk with hardness, but because of sodium it is better to use conductivity. I understand the total solids content, often referred to on this site, is also measured this way.

This technique does not measure not charged dissolved solids, such as sugar, but these concentrations are most often low. Still, in black water quite a lot of humus can be dissolved

But, what does hardness, or a high concentration of dissolved molecules or ions, do? They increase the osmotic pressure. A misleading term, unfortunately, as it is more a sucking power.

High concentrations suck water from lower concentrations - the result will be that in the end the differences in concentration are lower.

Back to fish eggs - eggs intended for soft water, such as amazonian plecos, will not explode in hard water, they will loose their water. But eggs from seafish will explode in this water.

If we look more closely, the eggs will have a similar concentration of salts, around a third of the cncentration of sea water, but an egg from a soft water fish will constanly be pumping out water - to compensate for the water sucked in by the high concedntration of salts. A sea fish on the other hand - these eggs are sucked dry and they will have to pump water in.

Pumping water in. while the egg is also sucking water itself - that will result in a blown up egg which could burst.

Not a pleco egg in hard water.

Therefore, the bursted pleco egg needs another explanation
[/quote]

If it's only the larger size eggs not hatching, I would look at dissolved oxygen. Have a look at how vigorous the male fans the clutch especially towards end of hatching.

You could "boil" the hatching tank with aeration elsewhere if you don't have an oxygen cylinder. If you do have oxygen, a very slow fine trickle of bubbles or make a reactor that passes water through trapped oxygen.