Having a quarantine tank is a commonly stressed aspect of keeping fish tanks. New fish can bring diseases, parasites, etc to an established tank, so quarantining them is a good way to ensure the current tank stays healthy. Fish already in the tank that show disease symptoms early can also be removed to the quarantine, saving other fish from contamination while allowing only the sick fish to be treated. Despite the obvious benefits of having a quarantine tank, most people seem happy go through life without a quarantine tank, at least until something terrible happens that a quarantine tank would have stopped from occurring. 

That being said, I don’t have a quarantine tank. I keep a quarantine ready setup on hand at all times instead. This way, I don’t need to have an empty tank running at all time just in case something goes wrong. Here’s what you’ll need to do that same:

1. Seeded filter media – whether you keep an extra few sponges, filter floss, or other media in a HOB filter or a power head with a pre-filter sponge, this media can be used to eliminate the need for cycling a new, small tank.
2. Water from an existing, cycled fish tank – using water from the same tank the fish came from can help reduce stress if quarantining injured or ill fish you already had in the primary tank. New fish/inverts can benefit from using water from the tank you intend to place them in. Ideally, water will be taken a few days after a water change.
3. Heater – to keep the quarantine at about the same temperature as the primary tank. An adjustable heater is preferred, because treating some health issues for specific creatures can be enhanced by making the water warmer/cooler than the primary tank.
4. Filter – I love the Azoo HOB filters for this. They have extra room to add in the seeded filter media, controllable flow, and are pretty inexpensive. Sick/injured fish often benefit from calmer water, requiring less energy for them to stay in place. New fish can take a heavier flow, which will help cycle the tank.
5. Tank – I keep a 10 gallon purchased at a PETCO dollar per gallon sale on hand for my quarantine. I keep it empty, with the spare filter and heater inside for quick setup when needed.

So long as you have space to store the quarantine tank itself, this is a great alternative to having an empty quarantine tank up and running all of the time!