Does pH and hardness matter with hatching woodcat eggs?

[mkinsella]

My water is pretty hard, TDS 280, KH 14, GH 14. pH is 7. My water is from a well and sometimes fluctuates a little but that's the average tank water parameters.
The last 2 times I tried hatching some Fisher's woodcat eggs, I had them in a separate hatching/fry tank. I had no fry and the eggs didn't even fungus or rot for about a week but I got no fry. The eggs just sat there until I gave up and cleaned out the hatching/fry tank. Temperature was 80F, 27C.

What I am not sure of is were the eggs just not viable for other reasons or could it have been the pH and hardness? I have heard some eggs won't develop or hatch if the water is too hard. The only "successful" spawn I had, I only had 7 fry.

Just wondering if someone with more experience might have some thoughts or tips?

[characinkid]

I've never kept or bred Fishers's, but my Intermedia are at a lower TDS and KH and a PH around 6.5. I can tell you that sometimes I get really good hatch rates and other times its maybe 50% with no apparent difference at all. Ive heard, and experienced, that raising wood cats to adult hood is usually around 10-20% rate.
I recently got eggs from T.gyrina and they were similar to yours. They looked ok to start with, but I saw no embryos in them and after approx 5-7 days they "melted" away. I assume that these were not fertile as some also turned white immediately.
Hope that this helps?

[Bas Pels]

I would say, fish can adapt.

Problem is, a fertilized egg is a new individual, which will have to start to adapt. But in very hard water, an egg of a soft water fish, will not have enough time for this adaptation.

That being said, the conclusion would be that all fishes would need water which resembles their original water much more for breeding than the parents do

I am not a breeder myself, but I would expect woordcats from Amazonia will require quite soft water to hatch.

On a more microscopic level, this is what happens

All life contains a similar amount of salt, 10 % in the cells. Egs too. Sweet water contains less salt, and thus the eggs will attract water from the surrounding, resultig in burst eggs. Eggs from fishes from this water are therefore laid with mechanisms to pump water out, precisely enough.

If a soft water egg is placed in hard water, it will pump more water out than needed. The egg will shrink. Theparents have adapted, that is, their pums work a little slower, but the egg did not have time to do so.

A hard water fish egg placed in soft water will pump too little, and therefore burst.

In sea water the water is more salty then the egg, and therefore water is actively pumped not out, but in.

[mkinsella]

Thanks for the replies, that's all helpful. She was ready to lay eggs again so I setup a separate tank for her lay in as I've done before but this time I added just a little RO water to reduce the hardness a bit. I didn't want to shock the breeding female as she's been bred and raised only in my well water. I'll see how it works. I have a trip coming up so it's not ideal timing but at the least I know when she's laid eggs and approx when she'll be ready again in a month, so I can get the timing better as well.

[aquaholic]

If the eggs are fertilized but simply stop developing at a certain stage, boost your dissolved oxygen level.

[mkinsella]

OK I definitely got it figured now because I've got wigglers. I'd say about 60% or more of the eggs look good but I'll know better in a few more days. I'm fairly certain it was the water hardness. I put just 20% RO water, so not a lot but it brought down the hardness. The pH came down a little but not a lot. I did also put in an extra air stone but everything else was the same as before. I don't know if this is helpful to anyone else but now I'm around 7-10 degrees GH and approx 10-12 degrees KH which is working. Previously I was at approx 14 degrees for both and that was too high. I don't know about other species but worth some consideration.

[Bas Pels]

Congratulations!!

[bekateen]

Continued luck!

Cheers, Eric

[mkinsella]

Thanks again for the replies and useful info, I really appreciate it. I don't have a lot of help or resources local to me, so to be able to come on here and ask questions, get advice or share my thoughts is an enormous help.