Quarantine and hospital tanks

Like all living things fish also contract diseases. Some of these diseases will be contagious. Hence you should treat this fish separately. Many in the hobby have a separate tank which serves as a quarantine/hospital tank. Quarantine tanks are also useful to hold new fish before releasing them with other fish in an established tank. This screening helps protect the established inhabitants from potential infections we don't know the new fish might carry.

The quarantine tank is a separate closed system in which we treat the fish while it is isolated from your main tank to make sure it is does not infect other fish. The tank is a bare bottom tank with a mature sponge filter and heater. Mature sponge filter is one which has been in an established tank and has developed a robust microbe colony to deal with the ammonia in the quarantine tank right away. Heater helps speed up the lifecycle of disease like ich as they affect the fish only in a certain stage of the life cycle of the germs. Keep the lights dim and make sure the tank is not disturbed. This helps to keep the fish calm. Any undue stress will aggravate its condition. A large enough bucket also serves this purpose being closed from all sides gives a sense of calm to the fish. If you do use a bucket make sure it is at least 5 gallons because in smaller containers the water quality can deteriorate within hours.

Basic Setup for a quarantine tank:- bare bottom tank, heater, sponge filter.

Given that the inhabitants of this tank are sick this tank has to be maintained more meticulously than your regular tank. Even though we are using a mature sponge filter to take care of the impurities I recommend a daily 10% water change. I prefer keeping the filter as a backup. This is important in the quarantine tank especially when you are treating diseased fish. We use various medicines in the quarantine tank for the harmful microbes troubling the fish however it is quite possible that the medicines will decimate the beneficial bacteria in your sponge filter. Also it helps in avoiding a build up of the medicine in the water column as higher concentrations of the medicines may also be toxic for the fish along with the germs. For general quarantine do frequent water changes, maintain stable temperature, some salt, and methylene blue should be added.

Makes-shift Quarantine bucket if  it costly, time-consuming or you do not have space for a dedicated tank

 How long do we keep the fish in the quarantine tank? I would advised that one month to be on the safe side. After that check the fish for any signs of disease, see if they are lively and are readily eating food.  Make sure you have done enough water changes to clear any left over medicinal chemicals in the quarantine system. Once you have ascertained the fish is healthy you can transfer them to the main tank using the same acclimatization method described in the previous post.

While you are treating your sick fish it also advisable to treat your main tank. Add some salt, gradually increase the temperature 2-3℃ over the regular temperature maintained, perform major water change 50-70% clean the gravel and if possible clean the hardscapes like driftwood or other decorations. This will help contain the infection. 

If we maintain good water quality, diseases will be rare unless they are introduced by you in the form of a sick fish or because of your laziness to do regular maintenance. Your tank can buffer impurities and toxic build-up but that does not mean you should stretch to the threshold. Even with the best of filter you should do a regular weekly water change.