My first ones I put six in a 20g long let them pair and then moved two to another tank and left my four breeders in the 20g long.
I like the 20g long over a standard 20g because the footprint(bottom) is much larger giving them more room for hiding/sleeping places. Caves can be made out by turning two terracotta plates together(put a rubberband around them) and a hole drilled out of it just big enough for dad BN to get into. They prefer one entrance. Or you can buy ceramic caves.
Here are some pics I wanted to share with you
Bristlenose wigglers
The prospective parents need to be conditioned on 80% veggies and 20% protein as opposed to the usual 90/20 percentages. Zucchini, shrimp pellets, and thawed frozen blood worms are good conditioners. because your feeding much heavier water changes will need to be stepped up.
I usually moved my male cave wigglers and all to a grow out tank so dad wouldn't be harassed by the other tank mates while he was tending to the babies

Carol