Post some pics of the new fry and let me look. I doubt they are all males although my kykesis (petenensis) are running heavy on males. The females might get to 2 inches max usually smaller. If fed well they get big and big Notho females are best for breeding. Use 2 females to a male as males are rough. Breed as soon as the males sex out fully as Nothos are short lived. There breeding water can be only slightly soft and acid and you might try regular water once and see how that spawning incubates and hatches.
Methylene Blue and Acriflivine are both good anti-fungal agents but most people use MB. You just put the eggs in a mild solution for a day or two and then transfer them to clean tank water. I prefer storing on wet pre-boiled in hard water(and thoroughly rinsed in hard water) peat moss placed in those Glad storage containers and checked and opened daily. But I think community tank breeding and raising is easiest. Just feed live bbs daily for unseen fry.
I have more velifera and kykesis fry and have distributed some. I am slowing down on the killie breeding with the move. The orange picta are producing. I have around 5 orange males now and a load of females. I think the cross of two monty strains has taken as the blue/green females are loaded. I hope they improve the color and size on the spotted. The nezzies are doing great as always. I have an especially nice big male in this generation. The Phalloceros are multiplying. My old lyretail and hi fin swords strains are dropping fry. I will be sending the kykesis, velifera, lyretail and hi fin swords, nezzies and monties if I can. I'm going to take a break from killies for a while with the move as they require more time and special care. I'm sending off my last N. symoensi eggs to Singapore and China!