I would be real careful putting lace rock in with fronts. Its sharp if its the one im thinking of. My fronts have scrapes on them from my round rocks i put in the tank, i had one that almost put its eye out on a rock all ready. It gouged the skin all the way off like you were peeling a carrot and stopped just at the eye, he had a peel of skin waving off his head for a few days, he was very lucky. Nothing sharp should go into the tank, i have seen lots of fronts with body and head gouges and lots of pics of gorgeous fronts that were missing eyeballs. They spook and ram stuff with their heads. If they got any bigger they would be tank busters. I watched my alpha being stupid and he darted around ramming his head into rocks and glass , the more he hit the more panicked he got, retarded fish LOL but thats typical for frontosa.