By whitespot I do mean Ichthyophthirius. And yes it kills any fish (adult or baby) very fast.
All fish have a thin mucous layer over their body. This is the slime people feel when handling a fish. The mucous helps the fish move through the water easier and also provides a layer of protection against disease organisms in the water.
If fish get stressed from poor water quality, chemicals, wrong temperature, external parasites, etc, they can produce more mucous and it can appear as a cream or white film over the body. Sometimes if can appear bumpy and you get creamy white lumps over the body or fins.
If the water quality is good then it could be whitespot. However, if none of the other fish have whitespot and no new fish have been obtained during the last 2 weeks, it's unlikely to be whitespot because whitespot has to be introduced into an aquarium from something like contaminated water, ornaments or plants, or a diseased fish. If nothing new has been brought in, and none of the other fish have whitespot, then where would this come from.
It's also why I asked if any of them were rubbing on objects in the tank. External protozoan infections like whitespot and velvet will irritate the fish and they rub on objects to try and dislodge the parasites. If none of the baby fish are rubbing/ flashing on object, then it is more likely to be mucous.