My koi spawned in 22 centigrade water, and water temperature in the hatching tanks is 28 centigrade. Is it safe to directly move koi eggs from 22 centigrade to 28 centigrade? What is the max temperature difference?
I'll start by saying I don't know. But I think I would go by an assumption that the eggs are at least as sensitive to water change as koi. Maybe you could put the eggs in a small tub of the 22 C water and then float it in the 28 C water for 3-4 hours, perhaps occasionally dipping a little water back and forth. Just a thought.
From 22 centigrade directly to 28 centigrade: about half have got mold, the other half have got eyes.
From 22 centigrade directly to 24 centigrade: About one third got mold, the others are transparent. Eyes are not visible yet.
On the other hand, the 28 centigrade water was not as heavily/effectively aerated as the 24 centigrade water. So my conclusion is that a difference of 6 centigrade is OK for koi eggs.