First of all, how old is the system?
Why is he trying to put a tang in a 36 or even damsels for that matter (especially with just a HoB filter)?
What is his husbandry routine?
If you need to remove fish larvae efficiently and safely, Chad Vossen makes a larval collector that a lot of well known breeders use.
http://reefbuilders.com/2013/11/25/unboxing-vossen-aquatics-larval-snagger/
As for raising the fry, I would suggest ignoring anyone trying to tell you it's easy...
Felix over at Reef Savvy is by far the best manufacturer. Insanely high quality control and amazing customer service.
Is that the same City Aquarium that maintains the large cylinder aquarium in the Dream Hotel in Manhattan and the SI Ferry Terminal? Food for thought.
http://www.advancedaquarist.com/2002/10/fish
Males will leave you with no doubt. If it's dull or not significantly colorful in the body it's probably a female.
Both of those species are sexually dimorphic. Sexing them should take all of two seconds or a google search for pics.
Size is also an issue since smaller individuals will most likely not have much color until they mature or turn male.
Those two are from the first 3 that were auctioned and our other pair are from the 2nd round.
I was just posting to tease Jarret, don't want to hijack so PM me if you have questions.