Corydoras - Eggs not hatching

[ptfish]

I have been trying my hand to breed burgessi and Gossei for a while now. For a while I have some success in getting the eggs to hatch but for the last couple of batch, none of the eggs will hatch, it will get fungus infection by about the 5th day.

The temperature is aroudn 25C and I place the eggs into small plastic container (about 1 litre) with airstone and mythelyne blue. The PH is more towards the acidic side (I don't know the exact PH as I don't test them).

I feed all my corydoras live black worms. I do my water change once a week (about 30%).

So what might be the cause of this? Infertility? If so, what is the possible cause?

Note that the parents are in 2'x1'x1' tanks (a colony of 6-7) with more male than females. Bare bottom with a sponge and a corner filter with activated carbon.

Any advise will be most appreciated.

Thanks.

Patrick

[apistomaster]

It sounds like the breeders are fertile so I'm thinking that trying a different method incubating the eggs might be worth a try. I have used a 5 gal tank set up with a small outside filter with a sponge covering the intake. It is important the this system is precycled. I put the eggs in a jar and the jar is placed directly under the filter return. The jar is just barely submerged so that the whole water volume is being circulated. This way the eggs are constantly being rinsed with clean water and the fry eventually escape over the sides of the jar as they become free swimming. My hypothesis is that a constant flow of clean well oxgenated water helps prevent fungus. It works for me on eggs from BN, Cory. sterbai and rams. An addition of methylene blue is optional. I try to avoid it unless even this method doesn't work.

[Coryman]

ptfish,

Have you read the sticky at the head of this forum, which deals with hatching eggs & raising fry.

Ian