[SalmanEskay]

This is my first time caring for betta fry. They are 8 days old and I'm feeding them bbs since 2 days. I didn't know this but I just read a post that the fry will die if they eat the unhatched eggs. I can see a lot of the eggs in the bottom (or maybe some of them are hatched bbs which died before the fry could eat them) and some of it is floating on the top surface. Now I have no idea how I can get them out of the tank to avoid contamination. I also don't know how I can separate the unhatched eggs from the hatched bbs during harvest. I have been using a spotlight in the bottom of hatchery to let the bbs settle down after turning off the air pump. Then I use a syringe to suck up the hatched bbs in the bottom, unfortunately there are unhatched eggs also pulled up.

 

[SalmanEskay]

In my experience they won't touch the eggs until they're quite a bit bigger since the eggs don't move. But of you're worried about water contamination I would siphon the bottom of the fry tank 20 minutes after feeding, and maybe move the light up a little higher so the BBS swim to the low-middle of your hatchery.

I am doing exactly that. But when you siphon, don't your fry also get sucked up? I carefully try not to but end up sucking 8-10 of the fries. I am using a syringe but when with that small of a hole, they still get sucked up and I have to again get them into the tank one by one.

 

[SalmanEskay]

I'm not sure i understand why unhatched eggs or eggs casings are getting into the tank. When you shut off the airstone in the bbs hatching bottle, the eggs float to the top and the bbs will settle around whatever light source you are using--flashlight, cell phone etc--at the bottom and can easily be siphoned out with airline tubing. Speaking of airline tubing, that's my siphon of choice for fry tanks.

No sir
In my observation, Some of the unhatched eggs (sometimes a good amount) do settle at the bottom and when you get the nauplii to settle down you end up with some unhatched ones as well. A workaround would be to use the light source in the middle rather than the bottom, it worked but I also observed that half of the hatched nauplii are unable to swim upwards or just don't care about light intensity as long as some light is hitting the bottom.

So like @mollyyymo said, I don't see what more I can do than removing the waste every other day or once in 3 days depending on the amount of organic waste.