Newie needs help

[Crazy Dragon]

Hi everyone,

I am new to killies and also new to this website. I have been reading the forum and some other articles about the Killie's egg. There is some questions I would like to ask the expert to enlighten me.

1) What happen if the eggs is due for wetting but were not wet for a month or 2 months. Will the eggs dies off.

2) If the egg is due to be wet but then there is no eye, does that mean the eggs are not fertilized.

Help greatly appreciated.

Best regards
hkyong

[TyroneGenade]

1) What happen if the eggs is due for wetting but were not wet for a month or 2 months. Will the eggs dies off.

Yes they can. This is the most often made mistake by people purchasing eggs from overseas. The eggs develop abnormally, not adhering to imagined incubation times, and then sit eyed-up for several weeks, wither and die. This is particularly problematic in warm areas where the temp is above 27°C as at this temp Notho eggs can develop to eyed-up state in only 2 or 3 weeks!

2) If the egg is due to be wet but then there is no eye, does that mean the eggs are not fertilized.

No, it merely means the egg has not escaped diapause I or II where the embryo rests waiting some or other cue to develop. A change in temperature or moisture can stimulate the eggs to escape diapause and develop. For Nothos keeping them at 27°C does the trick quite nicely.

Regards

[retro_gk]

I'm a bit confused here...aren't killie eggs designed to withstand long periods of dessication?? If so, then why would delayed wetting be a problem?

[TyroneGenade]

Yes, killi eggs are designed to withstand long periods of dessication and the trick they employ is diapause---arrested development (not the 1990s hip-hop band).

Marc Bellemans reports only finding eggs in diapause I and II in the wild when he sifted egg bearing mud in Sudan 3 months after the pond dried out. An eyed-up egg is in diapause III and in this state they are ready to go, all you need do is add water. But in this state they have very little energy reserves left to maintain themselves.

While cells are built up enzymaticly (with a rate stricly controled by developmental signals and at an optimum at a specific temperature), the degredation of cells and cellular componets proceed chemically (rate can double for every 10°C). The higher the temperature the faster the degrading reactions. To repair this damage the fry has to use its energy resources. Once these are gone the fry dies, but even before that the fry may of tapped into its muscle and other tissues burning its tissues and enzymes for energy to repair other damage which is why some eggs don't hatch even though they are eyed-up.

Keeping the eggs cooler will slow development and reduce the energy that needs to be invested in cell maintenance. That is why fish kept at lower temperatures live longer, not because their metabolisms are higher at higher temps. Research by Walford has shown that the metabolism (as measured by O2 use) is faster at lower temps in Aus. bellottii as compared to warmer temps.

Regards

[retro_gk]

Thanks for the explanation Tyrone. If I understand you correctly, eggs can be stored for longer intervals by preventing them from entering diapause III. Can this be attained by storing the eggs at lower temperatures?? If yes, how low?

In addition, the method used by most killie breeders to incubate eggs in peat retains some moisture in the peat, what if the peat were dried out completely before storage? How would that affect egg/fry survival?

tia

[TyroneGenade]

Totally dried out peat => low egg survival. It is not suggested.

I've had furzeri down to 4°C with only 2% loss in eggs but this is a bit extreme. 20°C should be OK for most species in extending diapause a bit... I'm not sure. A lot of work has been done on shortening incubation but not much on prolonging it.

Regards

[retro_gk]

Has anyone done any research on egg survival rates in the wild??