Hi, I've just spawned my C. regani and they have about 100, 2 week old fry. At the moment they are in a 40 x 15 x 18 tank, with sand substrate. I have bred this species quite a few times, this one iS the Rio Negro variant, I also have "purus" and "barcelos" at the moment.
no there usually isn't any specific things happen before they spawn. Females gain a nice red stomach and get full of eggs, they then select a spawning site, I've had them spawn in coconut shells, proper caves and under bog wood. Usual spawn size in around 100 to 150.
They usually respond to lowering the ph and also gh, mine have just spawned in 5.5 ph, and 2gh, but you don't need water parameters this low.
Fry free swim after about 1 week, let yolk sack dissapered, then feed b/S nauplii.
Speed of growth is quite amazing, the fry can be ready to spawn at around 13 weeks !!!!
Growing fry on is easy, I remove mine from parents into own tank at 4 weeks, given daily, small water changes and fed 4 times a day on chopped frozen food, they grow like and.
Good luck
Graham