General cure is not really considered reef safe. The fuzzy you have had for 8 months is likely parasite free, they would have succumbed to any infestation by now. The yellow still needs close observation, they can appear to be fine for as long as a couple of months, I've seen them live for as long as 3 months. Some things to look for, stingy poo is one, you can even see stingy bits in the tank if not hanging from his butt. When it's bad it will be white but any stringy hanging on is bad. While fuzzies will beg alot for food, an exaggerated insatiable appetite can be the beginning indicators, as well as losing color. Prazi pro is reef safe but you would combine seachem metro and focus in the food you are feeding. Because the metro needs to get into their system continually for about 2 weeks, this is generally not the best method. General cure has both these ingredients, it's the metro part that is not considered reef safe. You may get some better answers about treating with general cure in reef in the reef discussion or disease discussion. Using in a reef with tons of rock and coral can be tricky, displacement can make dosage difficult, be careful. General cure is meant to be dosed once, then repeat 48 hours later, then a water change and carbon 48 after 2nd dose,
What size tank are they in and what size are they. You will not be able to definitively sex them until they about 4.5", at least until 4". If the tank is under 120 to 150g you may have trouble with 2 males in the same tank, even then it's 50/50. A male will have over 6 bands on the pectoral fins while the female will have under 6. With 6 bands it may take longer to determine.
If these guys were like under 2" you may have gotten lucky, the smaller ones escape parasites from time to time. It's about what they were being fed along the way.