Is a Quarantine Tank Necessary?
A funny thing happened on my quest for a breeding pair of Discus.  I had the opportunity to add two beautiful Wild Green F1 and another Alenquer Red F3 Discus to my stock and did so after a 10 day quarantine period.  The fish looked great and were in fantastic shape.  They were begging for food and eating every type of food that I offered them.  I grew impatient and decided to put them in my tanks after only 10 days.  What harm could come from that? A proper quarantine procedure involves at least 4 weeks of isolation, some suggest 6 weeks.  This should be followed by the addition of one or more Discus from your stock being added to the quarantine tank for another week or more.  The purpose of the first 4-6 weeks is to ensure that the new fish are healthy and have recovered from the stress of shipping.  It also gives you the ability to slowly acclimate them to your water conditions if they differ greatly from those of the breeder.  One other benefit is that they can become accustomed to your feeding habits and types of food offered without the competition from the other fish that are already familiar with the food.  By moving one or more of your stock fish to the quarantine tank you can determine whether your fish are carrying some disease/bacteria/virus that may affect the new fish or vice versa. I took a shortcut on the first step and ignored the second step.  As it turned out the new fish must have been carriers of Columnaris.  I assume that they had been through this disease and were now immune to it but still had the ability to transfer it to other fish.  I’m not positive about the viability of this scenario and I am trying to find out how this happened and if this is typical of healthy fish.  And I’m not pointing fingers here.  If I were, the first person who is at fault is me for my improper quarantine procedures. The new fish were added to one of my tanks on 12/8/00.  Here is a picture of how my fish looked on 12/11/00.  I was just starting to notice that these fish were becoming much less active compared to the other tanks.  On 12/15/00 2 of them (the largest 2) started to lie down against the driftwood and refused to eat.  I isolated them in a separate tank and added a tablespoon of salt per 10 gallons and increased the temperature to 92ºF.
On 12/16/00 I started a salt treatment of a different magnitude.  A well-known breeder in my city warned me that my fish would die if I medicated them and that the small amount of salt that I had treated them with would be insufficient to help them through this.  As it turned out my fish had Columnaris.  He suggested that I add one pound of salt to my 50-gallon tank and increase the temperature to 92ºF.  By then all tanks had some fish that were ill so I treated the entire system.  Here’s some pictures of the progress of the disease as it went through my tanks.
It is not easy to show these pictures publicly.  Not one of my prouder accomplishments.  I only lost one Red Spotted Green to this outbreak.  There were still a few fish that were black and hiding a week later but the majority of the fish had recovered.  Since salt was used as a medication there should not be any long term side effects for the fish.  I plan on working on my patience in the future and suggest that you learn from my mistakes rather than repeating them.  These fish are tough but there’s no reason to put them through this type of experience.