Avoid gravel and use fine substrate...and like the guys said...ditch any plecos, synos...or anything that will suck slime coat off your bichirs!!! i learnt this the hard way... now i have a delhezi in the freezer...
....besides, all plecos do is make more mess than they clean! hehe...
Well an update, all the plecos have gone they are doing brilliant, loads of hiding places and are eating I love em. I never see em so i snapped em all up.