I have just this night lost one of my zebra danios. I have been watching her closely the past few days, as she had become bloated. However, it was gravid bloating- I've seen it before in my pearl and leopard danios. Now, they have always passed the eggs no problem, so when this girl hadn't I started to get worried. Long story short, she became increasingly lethargic, began hanging at the top of the tank and was having quite rapid gill movement. As I was watching her, she began to pass the eggs, however they looked fungus-y, and stopped coming as soon as they started and remained by her body. I went to get my camera, came back and my honey gourami had gotten into the breeding trap I was holding her in, and was eating at the eggs. By the time I separated them, she was well and truly dead, already being pretty dead/dying as she passed the eggs. I wasn't able to take a picture, which would have explained it so much better :(
All of the other fish in the tank seem okay, but I'm worried. Is there a defect that can stop danios being able to pass eggs? Is there a disease that causes this? What can I do to lessen any impact on my other fish? And will eating the eggs from this fish end my honey gourami as well?

16g
1x honey gourami (male, and a bully)
6x danios, now 5 :(
Readings are at zero, I have an air stone, it's planted and has a power filter designed for a 20g along with a foam filter again designed for a 20g
It's been set up for a year now, fish have been in for six-seven months.

Any help would be gratefully accepted, I'm really at a loss and want to act now before it's too late :(

By "readings at zero", do you mean ammonia, nitrite, nitrate, and pH? If so, I think there is something dreadfully wrong with your tank. Also, how are you testing?

The only thing I can think of that might be related to white fuzzy eggs are internal parasites. If there are any other fish in the tank that show signs like that and start pooping out white stuff, then I would pull the carbon and start dosing anti-parasitic meds.

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Officially fishless until after the move....tune in later for details!

Sorry, I just realised what I wrote didn't make much sense!
Ammonia and nitrites are at zero, immediately after the death I did a water change and checked the water, and nitrates were at 9ppm.
Checked the water again and the ammonia and nitrites still at 0, nitrates at 5ppm.
pH is at 7.2, I'm testing with the API liquid kit because the strips have let me down before.
I've pulled the carbon but have been worried about medicating without knowing for definite, keeping an eye on other fish and doing frequent water changes- should I raise/lower temperature, or add salt? I'm reading mixed comments on both :/