Quarantine tanks for fish

Good advice for all fish keepers, whether they keep just a couple of goldfish or an exotic marine set-up, is never to introduce a new fish into the tank without first placing it in quarantine for a certain period of time first. Quarantine tanks are useful for all sorts of things as well as housing new fish, such as for isolating a fish that appears to be ill and needs treatment, or for use with pregnant fish so that they can spawn and hatch their fry with less chance of it being eaten by their tank mates!

It is a good idea for keepers of all sorts of fish to have a quarantine tank set up and ready to use at all times, and in this article, we will look at why you should have one, and how to use it. Read on to learn more.

The reasons for keeping a quarantine tank

If you think that simply having an empty glass tank stored away for use if you need it is sufficient, think again! In order to fulfil a useful purpose, your quarantine tank should be set up and cared for much like your regular tank, so that it is ready to use at any time. There are several reasons for why having a quarantine tank ready to go is a good idea, such as:

• To house new fish before you introduce them into your main tank and the other residents, so that you can observe them for some time and ensure that they are not ill, or carrying any health conditions that they can pass onto your main tank.
• In order to have a kind of “hospital” tank ready to use right away if one of your fish appear to be sick. This is not only in order to avoid transmitting any problems to the other fish in the main tank, but also so that you can medicate the quarantine tank without it affecting the other healthy fish.
• To house breeding fish, so that their fry do not get eaten by the other adults!
• As a standby for an emergency if something went wrong with your main tank, such as if the filtration or heater broke, or the tank developed a leak.

What does setting up a quarantine tank involve?

Setting up and maintaining a quarantine tank should be fairly cheap and simple, as it will be smaller than your main tank and will require less attention to be paid to its landscaping, as it is designed to be functional rather than decorative.

A basic small glass tank with filtration, aeration and a suitable substrate is all that is needed, with a tank heater for tropical fish, and other fixtures and fittings as needed for marine fish.

Assuming that the tank is not kept in a dark, dingy corner, you may not even need lighting, as it is usually advisable to leave the lights off on a tank containing a sick fish, or one that is stressed from moving.

Using your quarantine tank

If you notice that one of your fish are unwell or behaving oddly, moving them to the quarantine tank as soon as you spot the problem can go some way towards preventing the other tank residents from becoming sick. It also means that you can medicate the whole tank as needed, without worrying about the effect that this will have on the filtration or water parameters in your main tank. Try to ensure that the water quality and parameters in the quarantine tank as kept as close to that of the main tank as possible, to make the transition as stress-free as possible for your fish.

When you buy a new fish, you will obviously have done what you can to check that they are healthy before you buy them, and that they are not showing any signs of problems that may affect the rest of your fish. However, some problems will not become obvious right away, and this is why a quarantine tank can be helpful, to provide a holding space for a set period of time so that you can observe the newcomer.

Ideally, new fish should be isolated in your quarantine tank for two weeks, before you add them to the main tank.

It is important to thoroughly clean your quarantine tank and change the filter materials if it has been used to hold sick fish, both because the tank itself may harbour the source of illness, and because some common fish medications can affect healthy fish too. The quarantine tank should also have had a chance to recover and stabilise the new water within it after a thorough cleaning in between residents, and so it is important not to put newly bought fish into the same water that has previously held potentially sick fish.