[DJRansome]

Would a fish hold if eggs were not fertilized?

Yes

Could a different breed fertilize the eggs?

Yes

Could the fish be sick?

Yes

If the fryeri is blue it is probably not a female so then you would want to explore the possibility it is sick.

What other fish are in the tank? Fryeri are known to crossbreed with peacocks.

Females can hold unfertilized eggs, usually they spit/swallow in about a week if this happens.

 

[DJRansome]

Will she eat if she is holding?

Sometimes a couple of pellets. Sounds like you may have some fryeri/peacock fry.

 

[DJRansome]

I would let her spit in the main tank because what would you do with 20 or more hybrid babies?

If you want to salvage the fry you could move her to the hospital tank. Might want to wait at least a week since she is likely to spit or swallow around one week if the eggs are not fertilized.

Sounds like the hospital is not cycled (no fish for 2 months) so you would also want to add filter media or gravel from an established tank.

Might want to consider removing her permanently from the tank since an accidental female among males in an all-male tank may not remain healthy due to aggression.

 

[DJRansome]

The bacteria in the hospital tank will not survive without an ammonia source to feed them...either fish or ammonia. For a while yes. But not forever.