Most snakeheads can take poor water conditions for a while,in fact they are very intollerant of chlorine and metals in water,so many end up being killed by heavy water changes.They need aged water preferably for water changes so above suggestions should be fine.Pleurophthalma are one of few snakeheads that can be kept in a group and they stay mainly together especially when feeding.We have 5 and it is comical to see all 5 suddenly dart to the surface for air at the same time.