Incubation length - Is there a difference?

[HNLim]

I have read and seen many many posts etc. in forums, articles etc. that the length of incubation of goldfish eggs is around 5 to 9 days. In Singapore where we enjoy summer all year round with room temperatures of around 30+ degrees C our incubation time for goldfish seldom exceeds 2 days.

From the many spawns that I have done, it takes at times about less than 2 days for the eggs to hatch.

My question is; Is there a difference between one that takes 2 days to hatch and another that takes 9 days to hatch? If so, what are the difference?

[Virginia ranchu]

I hatch my eggs in an unheated aquarium that is about 65-68 degrees F. They pretty much always hatch on the fourth day. Higher temperatures can lead to a skewed sex ratio...more males than females I believe. I have also noticed that a cold shock to incubation eggs can cause deformities in ranchu. Spikey backs and single tails can be caused by temperature.

[Fishdork]

I have read of experiments in Japan and confirmed by others that hatching at 68F (20C) produces the highest percentage of double tailed fry. Hatching at cold temps increases single tailed nymphs. I don't know what range of temperatures were studied.

My opinion is at colder temperatures it seems like there is a greater chance of fungus, but I think that may just be in my head because there is more time to worry. Higher temps some infertile eggs don't have time to get really fuzzy. Colder temps good fertile eggs should stay good if not crowded against the bad eggs. For me, at warmer temperatures, the larvae seem more likely to curve their backs sharply as they starve in the first few days.

[mikroll]

interesting about the temperatures and tails. I have 3 spawns currently, 14Dec at 20°, 4 Feb and 15 Feb ( just hatched tonight) temperature is 22°C @ 4 days . and I think I shall count single / double % and see how it will compare with next months group sexing them will take a little while longer I think. In Summer sometimes spawns have hatched in 48 hours or less too.

[bekko]

I take whatever temperature the weather gives me. Usually about 70-72F (21C) in winter and 76-78F (25C) in summer. We have newly hatched fry year-round but most come along between February and June. Hatching is in three days in winter and 2 days in summer.

Spikes and single tails are never an issue... or at least the percentage is negligible. Sometimes, buttheads are a major issue and sometimes missing anals is a modest issue. Nonetheless, as noted in the tosakin thread, there is a lot of variation in overall quality from one spawn to the next. Of course, there is even more variability in overall quality between the goldfish varieties.

In a very general terms, I find that the first spawn of the season from an individual pair or trio is usually better than subsequent spawns in terms of overall quality. It does not seem to matter if the first spawn comes along in February or August, it is usually better and often bigger.

This leads me to wonder whether the dogma about overall quality being better when hatched at 68F is due to the fact that the first spawn of the season in a temperate climate usually happens when the temperature reaches 68F.

-steve