Thanks so much for the reply. That's really great info!
This pleco is about 3 inches already, so I'd expect there to be bristles at this point if there's gonna be. I guess I was more concerned that I just have a male that has no bristles...(?)
I have 2 albino bristlenose and 1 juvenile super red. The large one without bristles and chunkier body started doing some fine flapping just outside the cave. I had always assumed this was a female, but I thought this behavior was only males?