I haven't had any show any interest in spawning either.I have a bunch of driftwood and some large ceramic caves (AKA sewer pipes)... Lots of interaction but no spawning.
Matt
You just need more flow, I used to have a real pleco poop issue until I added some powerheads and bumped up my return pump. Now it all goes into the prefilterLove the colour and patterns on Royals, as well as the massive head compared to the body lol; but by God these fish can s*it!
I had one against my black sand, and I kid you not after 2 days it was covered in turd; painfully visible too