Andy Sager
Aquarium Advice Addict
What level nitrate do you consider high for the eggs?
That's a great question and today, you win the prize because I really don't know. That's right, I don't have all the answers ( just most of them. )
In my case, with Angels and other fish I artificially hatch, there is no nitrates in the water until after the eggs hatch because I start with clean fresh water and use just an airstone. Since no ammonia is being produced in this process, there is no nitrate. In my current situation, having the sponge filters in the tank prior to the eggs hatching helps with the ammonia but it produces nitrates and in those spawns where I did that, I lost them before the eggs hatched and I'm not sure what the level was in those tanks because I never tested for that. ( MY bad and I should know better.) With the cory eggs, the nitrate level was 80+ ppm when I tested this morning so since that is bad for fish, it may be worse for eggs. I just don't know. I did do a 50% water change and will do water changes daily until the eggs hatch or die to reduce the nitrate level. However, since it wasn't bad enough to make the breeders not spawn, it might be okay. Today, I see a number of eggs that look like they have a small white ball inside of them and some look clear. When I saw this the last spawn ( same male, different female) I thought these were going to be the dead eggs and they wound up hatching on me so I'm just sitting tight and waiting to see what happens this time. I do have both types of eggs on the plant I moved to the front of the tank so I can monitor what's happening.
With the plecos, it's much easier to tell as the eggs are a little larger and so are the embryos. I candle a Pleco egg and I can see the yolk sac clearly as well as the red veins pumping blood. Wasn't able to see that even with the last successful albino cory spawn.
Hope that answers your question.