hatching time delays

[ikarsai]

Hello,
I am reading this forum for a while, but this is my first post. So greetings everyone!
I am wondering if there is any research or experience on manipulating hatching of killi eggs. I am not talking about days or weeks here, but for longer times (months, years). So far I only read about tricks how to accelerate hatching. However, I am wondering, if we can store these eggs similar to the seeds of plants for long time somehow. Cooling them to 4 degree of celsius or keeping them in some environment that slow down development, but keep them alive. I would be grateful receiving some information about this. many thanks! Steve

[mozaqua]

Steve,

Some species can be kept for much longer than others in suspended animation. But if you are talking years, you might be talking about cryogenics not killi keeping.

A few species can be kept at fairly low temperatures and still hatch after 12-14 months. Some reports species such as Pronothobranchius kiyawensis lasting many years in peat before hatching. See Tyrone's E-book on that: http://tgenade.freeshell.org/killibook/ or ask him yourself he is a member of this forum.

So mostly I think the natural dormancy time of eggs is dependent on the species, and the temperature mainly.
I have read many documents on Brine shrimp, and Fairy shrimp cyst lasting over 30 years, and it is believed they could last up to 100 years.. But those are a bit different from fish eggs.


Regards

[ikarsai]

Hi,
Thanks for the answer and I think I need to be more clear. The problem I posted is interesting for me on 2 layers. One of them is an intellectual one. This is really about the limits (without cryogenics) what some annual species might do. The other one is practical and not relates to only annual species. Practically it would be very beneficial, if we can delay hatching without much loss, in case we traveling for example. Many mop spawner will hatch 10-14 days, but what happen, if i am away that time. If I could double hatching time, I could avoid problems. Much easier to find somebody to take care of adult fish or large fry than small ones, if we have to do a trip. While annuals allow more room due to longer development period, it would be useful to know how much room we really have and what is the environment which makes the best results. I asked Tyrone about this problem and he said there is not much research on this area. So I think it would be very useful to share our own experience on this and also stat to experiment.
Thanks a lot! Steve

[mozaqua]

Steve,

A lot of research has been done by guys like Scheel regarding egg development/ storage. Read some of his stuff, quite interesting. He remarked that eggs in a low oxygen mud seemed to delay development but many were lost (theory was hydrogen sulfide). Also Temperature being lower helps delay development.
My theory, the best way to store eggs for longer amounts of time is to delay the initial development. Scheel and others called these type of eggs "resting eggs" since they seem to not develop right away like the others, and thus last longer during shipment/storage.
It seems the ability to delay initial development varies between species. Also the ability to survive longer periods of suspended animation (fry is developed but does not hatch) varies by species.

But really, if you want to keep eggs from mop spawners (non-annuals) for a long time, there is not a lot you can do. Cryogenics might work, but does not sound like your talking about scientific experimental-theory which involves high cost equipment.

[Zeth]

where can I read Scheel notes?

[RonWill]

I'm not quite sure but you might want to go through "The Scheel Letters" instead. Tons of info if you care to read up.

For those wondering which TLA (Three Letter Abbreviation) belongs to which killifish species, read this.

BTW, David, where are you from? Mexico?

[TyroneGenade]

A few species can be kept at fairly low temperatures and still hatch after 12-14 months. Some reports species such as Pronothobranchius kiyawensis lasting many years in peat before hatching. See Tyrone's E-book on that: http://tgenade.freeshell.org/killibook/ or ask him yourself he is a member of this forum.

Wow! I had totally forgotten about that. Since then Ian Sainthouse also got a hatch of theirryi peat which was several years old. But no real research has gone into discovering what stops development. Once the embryo has invested its energy reserves in development it has to maintain that state of development or die from degeneration.

This is a very interesting subject and there is lots of anecdotal evidence that anoxic conditions do prevent the eggs escaping from Diapause I but no controlled research (i.e. how much oxygen is needed etc...). Likewise, temperature also hasn't been well explored. I've kept N. furzeri eggs at 4 degC for a week without ill effect (1 out of 10 eggs died) but have no idea just how long they can rest at 4 deg C. Given the high salt and organic compound content in the eggs they could probably survive temperatures below 0 as they won't freeze.

Kind regards

[mozaqua]

Wow! I had totally forgotten about that. Since then Ian Sainthouse also got a hatch of theirryi peat which was several years old. But no real research has gone into discovering what stops development. Once the embryo has invested its energy reserves in development it has to maintain that state of development or die from degeneration.

This is a very interesting subject and there is lots of anecdotal evidence that anoxic conditions do prevent the eggs escaping from Diapause I but no controlled research (i.e. how much oxygen is needed etc...). Likewise, temperature also hasn't been well explored. I've kept N. furzeri eggs at 4 degC for a week without ill effect (1 out of 10 eggs died) but have no idea just how long they can rest at 4 deg C. Given the high salt and organic compound content in the eggs they could probably survive temperatures below 0 as they won't freeze.

Kind regards

Wow, F. thierryi eggs too! Cool, I was wanting to get some of those.

My theory is low oxygen is one factor which prevents the eggs from beginning to develop in the first place. [Tyrone, I am assuming you are talking about the diapause state of a developed embryo?] I have had several species of Nothos which did not begin to develop until I opened the bag to air it out a bit. Anyone else had this experience??

Once the embryo has invested its energy reserves in development it has to maintain that state of development or die from degeneration.

Ah, that may be why my A. australe eggs disappeared when I left them in the peat (2 days too long)... as I don't think they are able to survive inside the egg very long once developed.

Regards