Soft water and hatching ...

[JeffreyRichard]

OK, we know that discus spawning in soft (and acid) water will generally produce better spawns, that is a better hatch rate, than in harder water.

Question ... is it more important for the water to be soft (lets say less than 100 ppm) for FERTILIZATION, or during the subsequent hatching process?

I'm trying to determine if eggs that were laid and fertilized in tap water (say 150 PPM), if moved to acid RO water (50-70 ppm) would hatch out, or do the eggs need to have been fertilized in the soft water to gain the benefit?

[gary1218]

My understanding is that it is the soft water that permits the sperm to penetrate the egg wall. So, you would need the soft water during fertilization. After that I'm not sure if changing the eggs to a softer or harder water has any effect on hatching.

GARY

[Carol_Roberts]

That is a really good question - I hope someone has actually tested this. I don't know the answer. I keep the water soft until the eggs hatch and then start doing aged tap water changes to bring up hardness.

[shamsoo]

hi, if you go thru my recent post artificial hatching, my pair laid eggs in 200 tds and eggs hatched in 100 tds, what I had read, in spawning process eggs are surrounded by a multitude of fast moving sperm. One of them penetrates the micropyle, fertilizing the egg. The micropyle closes as the egg swell . In such conditions some ripe eggs are not fertilized because the high motility of the sperm last for only few seconds and the egg micropyle closes within limited time, after their contact with water. different fishes have different timings,in case of discus male has 2 minutes to fertilize the eggs before a protective covering forms on the egg to prevent fertilization. now the hatching part If you have too many salts in the water, the eggs won't hatch, as calcium and other minerals will harden the outer shell of eggs and fry cannot burst out from the eggs, this is why we use soft water for better hatchout , HTH :o :o :o :o

[Willie]

Most enzymes are regulated by calcium (less often magnesium) ion concentrations, including the ones in cell membranes. So, it the eggs are hatched in high calcium concentrations, the membrane immediately begins to change in some manner that impedes sperm penetration. Short answer, Jeff, they need to hatch in soft water. Note that its the calcium that do damage, not hardness per se. So you can get decent hatch rates in softened water, where calcium is replaced with sodium.

Willie