The Hospital tank can be one of the most valuable tools when keeping tropical fish. The size of your hospital tank (HT) should be as small as possible yet still comfortably house any fish you may have (unless you have super large fish).

A 5 or 10 gallon is usually perfect. Keep the interior of this tank as spartan as possible, no gravel, no decoration, and no plants. This will make cleaning and sterilization easier after treatment.

These tanks do not need to be permanently set up although you should have the filter seeded with bacteria or seeded media to transfer. Many people use sponge filters that slip over their filter intake tube for maintaining seeded media. You can transfer these sponges to your HT when needed. You can also keep some extra filter floss or filter pad material in your main tank filter. Remove these and install in you HT filter when needed. If using medications in this HT, DO NOT use activated carbon.

When the time comes to put this HT to use, fill it with water that is the same temperature as the water in your main tank. Treat the water with your favorite conditioner to remove chlorine and install an air stone. Ensure the temperatures are the same before transferring any fish to the HT.

Nitrifying bacteria will not survive in a tank with no fish. The fish waste is the food for the bacteria and without this food the bacteria will starve and die off. You may be able to continually add ammonia, fishless cycling process, but in my opinion this is a waste of electricity to keep these tanks running just in case.

You should have lighting but it should not be very strong. I found the best filter is a hang on type power filter. They are the easiest to service. If possible keep the HT in an area away from traffic. The less they are bothered by outside influences, the less stress they will receive. After the illness is cured, install activated carbon in the filter to remove the medications from the water and continue to monitor the fish in the HT for another week or so before returning it to the main tank.

After you remove the fish from the HT, you must clean the tank accordingly for the disease the fish was treated for. Some just need a good washing out with HOT water and the more lethal need additional sterilization. After cleaning, rinsing, rinsing, rinsing, and drying, set the tank upside down to keep airborne contaminants from settling in the tank. Your HT is now ready and waiting for the next time it is needed to be put into service.