Good advice there Platy 252.
I'll just add a few extra bits.
Aging.....yep. These guys age (to the extent that they are medically significant), so Platy's comments are not that much of an exaggeration.
Often, the aging process just after the final spawing is so rapid that it is un-believable; one day a fine healthy vibrant male, the next a 150 year old trout.

(maybe an exaggeration there though).
If them eggs work for you, let us know. I may try some of the shipped ones myself oneday (when I could be bothered going on the internet

)
In the picture of
N.rachovii, this shows the breeding set-up in one of my tanks (but, of course, that picture was taken some years and the male is no longer with us).
This is what I used to help reduce the aggressive nature of the males on the females.
A small glass tank with a raised stilts bottom is placed within the main tank. In the small tank is the breeding material.
The idea is that a female can easily enter and leave the small tank, and if the male pursues then he tends to find a glass water rather than a straight line for the female. I found females lasted much longer with this set-up.
ian