Peppered Cory Fry Dying, Literally Right Away

[That'sNotMyName]

Hello everyone! I'm hoping someone on this forum can help me, my LFS has no idea....

I have a 20 gallon, fully planted tank. The only thing in it are 6 peppered corys (Corydoras paleatus, 1 female and 5 males), a mystery snail, a nerite snail, and 2 juvenile guppies that showed up a while back as hitchhikers on a Brazilian Pennywort mat.

The corys breed like mad, I don't know why, I guess they like their home. The female lays roughly every 3 days, sometimes less. She's been doing this for around a month now. But not a single fry has made it past a few hours.

I've use Bio-active Live Shrimp water in my tank exclusively ever since my large mystery snail started to experience some shell damage (long story, but I've had him for over a year, and he's pretty awesome). This was what was in my tank when I got my "little cat friends". Originally, all that was in that tank was the snails and a betta. When the betta passed, I got my little cory school. They lived in it happily for around a month, and then started this breeding frenzy. At first we thought we'd leave them to their own devices, if the eggs made it, then we were lucky. Then we realized that the corys really liked caviar, and I bought a breeding box that goes on the outside of the tank and cycles water through, to put the eggs in. This is how we know the fry aren't making it. Some of them hatch, and then die almost immediately. Some don't hatch at all.

The thing is, I know that the PH is high. It's the way it comes out of the box. I have 2 pieces of mopani wood, and I have peat moss (fluval peat granules in a filter bag in my AquaClear), but my water is between 8 and 8.5 PH. I'm hesitant to use chemicals to lower it, and I'm not sure that is what the issue is with the fry. Literally all of my other water perimeters are perfect, and I test them once a week. I even tested them again just before posting this. I don't add anything to my water, I even stopped fertilizing once they started breeding (I was using Aquaviro envy), so I stopped that a month ago. My LFS is the one that suggested the water for my snail, and is the one that suggested my school of cats when my betta died. They knew that my PH was high, but thought it should be fine. Of course, now that they are breeding, no one knows anything about it.

Could PH alone be enough to make not a single fry out of hundreds of eggs make it? Should I add chemicals to my water even though everything else in the tank is healthy?

I've included a pic of my tank in case that helps. There are around 10 eggs in the breeder box right now.

[Tetranerd]

You might have to choose between a happy snail, and Cory fry. If you continue to try to provide for the snails needs, you may be lacking in what your corys need. Peat, if fresh can be locking up some of the minerals in the special water your buying.
If you want Cory babies then I would suggest using tap water and prime. Feed the adults well, and take care of your plants needs. Healthy plants will only help all inhabitants be a little more healthy and stable.
I use a net breeder in the main parents tank. Put all the eggs in the net and throw in a healthy clump or moss or hair algae if you don't have moss. Let nature take its course with the babies. And don't stress when you lose fry. You don't sound like you purchased the corydoras with the intention of breeding and raising fry. So enjoy them, learn from each batch of eggs, and hopefully you will have fry growing in no time. Just keep it simple and if the babies live great, if not then at least all inhabitants of the tank will be taken care of with the extra care and fertilizer! Healthy plants seem to help create a better environment.

[That'sNotMyName]

I see what you mean. I am just trying to make sense of how I have a tank that seems to be so healthy in every other respect, but can't seem to sustain fry, even if the adults think it should. Apparently, adult fish aren't smart. Who knew?

I do have moss in breeding tank too, you can see the balls in the pic. Apparently for my own amusement, certainty not for the benefit of the nonexistent fry.

Can you tell me what this "prime" product is? I used to condition my tap water before, but for a healthy betta, not corys. I've been using the shrimp water for maybe 4 months now and my poor snail is still having issues with his shell (and he has a wondershell, and he gets Kens snail food with added calcium, and I was adding vitamin D drops for a month, to no avail. He's just destined to be difficult I guess. Considering I got him from PetSmart in the first place, I should be happy he made it past a year.) I'm not opposed to going back to my tap water, gradually of course.

[gossei]

Prime is a dechlorinator made by Seachem.

Blaise