PROBLEMS WITH EGGS OF CORYDORAS TRILINEATUS

[cartouche]

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.

[cartouche]

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.

[RiC]

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%...

[kim m]

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

[cartouche]

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.