All Our Eggs Are Unfertile

[dwarfgourami]

Well, the peppered corys' that is, not speaking personally here (I consider myself to have done my bit for posterity). They have been spawning on and off since September, ever since they first found out what to do. At first the eggs got eaten/were not saved under proper conditions. Lately I have had a proper tank set up with good aeration etc and transferred plants with eggs on, but they still have not hatched. (I've had to be really vigilant too as they eat most of the eggs during the act.) The adults have been well fed and their water stats are good.

What do you think is going on here? Could it be because:

they are still young (bought as juveniles 8 mths ago)?

my water is too hard/alkaline?

there are not enough males? (but the 2 males I have seem to work one female first, then the other)

they are not clever enough?

or

Santa knows he's not getting me another tank for Christmas anyway?

 

[Tokis-Phoenix]

Do the eggs go white/fluffy after a couple of days? Is the tank cycled and does it have any fish in it? How long are you waiting for the eggs to hatch?

 

[Inchworm]

Hi dwarfgourami

I can well understand your frustration with them! Peppered corys (c. paleatus) are terrible egg eaters and I only managed to save a few of their eggs myself, before I gave up on them.

I take it that they are just not hatching, and eventually going to fungus, right? The first thing I would think is that they are being damaged when you're moving them. It's not the easiest thing to do successfully, but if you are moving them on plants, they should be OK. That is, of course, if they are under water the whole time.

I wouldn't worry about the water hardness or pH either, at least not at this point. If the parents are doing well enough in it to spawn, they should hatch normally. I've never heard of peppered corys being overly particular about this.

The usual cause of infertility is, as you mentioned, too few males. But, I agree with you that if there is only one female active at a time, two males should be able to fertilize them. Even if they are not all fertilized, you should still have plenty of viable ones.

The usual cause of fungus and egg deterioration is insufficient water circulation over the eggs. They need a lot of water movement to keep the healthy for the four days, or so, that it takes them to hatch. Place an airstone directly under them, or at least very close. If you are hatching them in a clean, bare bottomed tank, you might also want to add a drop of methylene blue for each gallon of water. This will help retard the growth of fungus, but will not take the place of good circulation.

What colors are the eggs before they fungus? Depending on the species, they will normally darken somewhat before they hatch. Is this happening at all? If so, it's a good indication that they have been fertilized and that something is interfering with them before it happens.

 

[dwarfgourami]

The eggs are not darkening, neither the ones moved to extra tank, nor the ones left in main tank. They stay white/semi-transparent well over the 4 days and eventually fungus if I do not remove them. I have not seen any eggs showing signs of being fertile before they went to fluff. I have tried various positions of the airstone, and the aeration of the hatching tank-in-spe is pretty impressive anyway. I'm beginning to think Santa is trying to tell me something...

The other thing that struck me is that they never seem to lay very many eggs, not compared to what I thought was the norm. The female often only has only 1 or 2 in her clutch and then seems to take a very long time to lay them. I have done my best to provide nice egglaying plants and think the corys are being well fed (they look in very good condition, with a sort of shine to them, much brighter than when I first got them).

 

[Inchworm]

Hi dwarfgourami

I've been giving thought to this, but have to admit that I'm still at a loss for the answer. If your problem was with a less easily bred fish, it would just be one of those things.......... But C. paleatus are not supposed to be difficult in this regard.

You mentioned water hardness and alkalinity. Are yours extreme? How about the water temperature? Could it be too high?