mss....it's hard to tell size-wise, it's more about maturity/age. Females usually are ready to spawn around 2 yrs old and males a little older at 3 yrs.
My females were about 4"-5" when they started dropping their egg tubes and my males were about 7"........but again, it's more about how old they are which sometimes is very hard to do unless you raise them from fry.
Liz, my moba frontosa colony was busy this year.........they've spawned several times since last Nov.........over 125 F1 moba fry.....WOW!!!!
I have 2 moba mommas holding eggs right now and will most likely strip them this Sat. The oldest fry will be 25-27 days post-spawn and the youngest about 15-16 days old. I'll strip both on the same day to make it less stressful for the colony and the momma with the younger fry.
I have a 3rd moba female......she's jet black and she's due to drop a tube sometime this month........hopefully not before this Saturday.