I'm curious, would it do any harm if they used the sealed off small flower pot? I now know that their natural instinct prefers small spaces so I was going to pull that pot out and find something more narrow. I went into the fish room to do so and sure enough, the male has claimed the pot and has been inside with his head peeking out all night.
I'll put an additional cave in but it seems,like he has claimed his space. The pot is completely closed off so the bigger fish can't get in and harass the male. pic is what he is in now (before I put it in)