breeding common bristlenose

[amandakate]

hi guys I have a 180L tank that currently only has bristlenose catfish in it, I started with 2 that are around 8-10cm and bought 8 more that are about 4-6cm, my 2 adults(8-10cm) recently bred for the first time and now have 29 babies at approx. 2cm, my question is how many bristlenose can I have in that tank before it becomes over crowded? keeping in mind there are no other fish in the tank. (they died of white spot and I never decided on what new fish to get while the 2 catfish survived) a couple of the smaller ones are starting to show interest in each other too but im not sure how big they need to be to breed, should I move the babies to another tank if they breed again or will there be enough space for more fry? once they get a bit bigger I plan on selling them but not sure how well they sell around here.