Originally Posted by Bectan01
These are important lessons in salt water, you can't overstock a tank ( even if you plan on upgrading later) and you must quarantine new arrivals. If you can't afford to set up a QT or hospital tank you can't afford the hobby! It's the cold hard truth I am afraid. No medicine will cure ich, the only ways are to treat in a separate tank with either copper or hypersalinity - you must then leave your tank fallow (fish less) for 6-8 weeks in order for the ich to die off.
I don't have a quarantine tank, so I'm treating my main display with copper treatment. Should be safe for fish, but a couple of my snails have died as a consequence. I also hear it will kill some of the BB (but not completely). But it's not a lost cause. The fish should get better and the ich should treat after the allotted time. Overall, you do not "NEED" a quarantine tank, but it is recommended to have one to avoid casualties like mine.