I have answered this question on many many occasions in the past.
This is just another Gimmick, get rich quick scheme.
Admittadly to a novice who have seen highly coloured killifish in books etc, this seems and inviting purchase.
The reality of the thing is that the eggs will almost certainly be from the Nothobranchius genus (Africian annuals)
They dont tell you which species. The only species I would recommend to the beginner would be N. guentheri or palmqvisti
I have known companies send Rachovi or similar harder to rear species to which the enevitable happens. The novice looses everything.
Do yourself a favour. if you are interested in Killifish contact a recommended body, join their ranks and from there you will be able to put yourself in the know as to where to and how to get hold of Killifish eggs or fish.
Forget these Gimmicks.
Regards
C