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Hi, I would need some advice. I just bought a group of 10 Corydoras trilineatus, very well coloured fish (see Aqualog page 47) in perfect condition, and after 9 days in my tank, they started to spawn like crazy. The first spawning lasted 5 days and I collected 137 eggs total. After a four days' pause, they started to spawn again and in the evening I found 104 eggs. However, 60-100% (ca. 80% in the average) eggs turn white the next day after spawning. And this is not everything: Even the clear ones gradually turn white in the following days.

So, from the first 137 eggs only 14 were healthy after 4 days. Since I experimented with developmental water, from the 14 eggs only 1 piece (out of two) hatched in 11 dGH, pH 6,5. Another 12 eggs desintegrated in jars with chemistry ranging between 4-8 dGH, pH 6,5-6,8.

From the second spawning, 20 eggs were healthy after 1 day and now, after 2 days, only 10 are still clear. In this second case, I placed the eggs both in the water from the tank with adults (that has 11 dGH, pH 6,5) and in a fresh water with the same chemistry. The result was similarly bad in both cases. Since I read Ian Fuller's warning that trilinatus eggs are temperature-sensitive, I always place them in water that has the same temperature or is 1-2 C warmer than the water in the tank with adults.

Although I am sure that sooner or later I will solve this problem, I would welcome some suggestions, because it can save a lot of eggs to me. I don't exclude that the adult fish may be largely infertile, or that the eggs turn white because the fish spawned after a long time and as you all know, first spawnings in the beginning of a spawning period are usually bad, because the eggs are overriped. However, I don't understand, why even the fertile ones gradually die. This is unusual. Further, it was recommended to me to place the eggs in a soft water, 4 dGH, pH 6-6,5, because it is allegedly ideal for trilineatus. However, the eggs obviously desintegrate in such a water and hatch rather in harder water.

In the end, all 104 turned white... Today I found another eggs.

No ideas or suggestions? I know that it is difficult to judge it. I will probably have to solve it on my own.

Maybe you could try to transfer the eggs in the same water as that of the tank (you take one gallon out for instance); I had the same situation as yours when I used a different water (although at the same temperature and apparently same parameters); after I changed that, I had 100% eggs that hatched, or almost 100%...

Some years ago I bought 10 C. davidsandsi juveniles.

Last year they started spawning...1 or 2 spawnings of 20-30 eggs a week. For the first 2 or 3 months all eggs fungused/were infertile. The suddently all eggs atrated to hatch without me changing anything.

Perhaps you just need patience

RiC wrote:Maybe you could try to transfer the eggs in the same water as that of the tank (you take one gallon out for instance); I had the same situation as yours when I used a different water (although at the same temperature and apparently same parameters); after I changed that, I had 100% eggs that hatched, or almost 100%...

I stated that I had already done it! But with the same result.

I let the eggs from the last spawning in the tank through the night. In the morning I found 10 eggs total, from which 7 were clear. This is an unusually high percentage, but I don't expect that all of them would survive the following days.

I think that I should rather wait, that's true. In the meantime, I will experiment with developmental water.