So. You’re a new fishkeeper. Your tank is fully cycled and now you're looking at a tank full of fish that are hopefully thriving.
Your next thought is probably going to be about getting more fish. You spend some time carrying out research, looking for fish that are compatible with your established stock and water chemistry and then it’s off to the LFS (Local Fish Shop) to buy more of your finned friends. You put them into your tank and soon afterwards, you notice your fish aren't well.
At this point, chances are, you'll seek advice – either from the pet shop, where they'll probably sell you an over-the-counter med which may or may not work, or on a fish keeping forum such as ours, where you'll be guaranteed to be asked 2 questions (amongst others, if you're new to the forum too): When was the last time you added new fish/live plants, and Did you quarantine.
Sadly, for many people, the answer to #2 is “no, I didn't quarantine”, and for a number of reasons.
The majority of fish pathogens are introduced to an established tank with new stock, so it’s no coincidence that the fish are ill so soon after the introduction of new fish. Nowadays, we can’t rely on the breeders or LFS to quarantine new stock because they just keep them on UV (ultraviolet) sterilizers and/or treat them with meds/salt, which for the shop means transmission levels are kept to a minimum, but for you, it means the fish go from UV in the shop, to no UV in the home, where the diseases can take hold and you get an outbreak that can then go on to devastate all your current stock.
That’s why it’s so important to quarantine all additional stock before adding them to your established tank. It gives you peace of mind that any disease outbreaks are limited to the fish in the QT and the fish in the main tank are safe. The QT (Quarantine Tank) is therefore as important as test kits and is worth its weight in solid gold to beginner and more experienced fishkeepers alike.
There are other benefits of having a spare tank, too. For example, you could use the tank for:
1. The isolation of sick or injured fish which needs treatment, or of an aggressive fish which is terrorizing your other stock
2. As a breeding/fry raising tank
3. An evacuation tank if the unthinkable happens and your main tank develops a leak.
There must be loads of reasons for not having a quarantine regime and one of the most common reasons for the fishkeeping beginner is the lack of space or money for another tank. We sympathise, but we’re not talking about a permanent set-up here. Strictly speaking, the QT doesn't even have to be a purpose-built fish tank. A food-grade plastic container from any hardware store will do the job – it just has to be big enough to humanely house your largest fish at adult size for a short time during treatment. Other equipment includes all the familiar equipment you'll find in your main set up – i.e. a filter, heater (for temperate/tropical fish), thermometer, a background and décor for the fish to hide in. Any left over substrate from the main tank could be used in the QT, but whether you use substrate or not is down to personal choice. Buckets/containers for water changes and nets should be kept separate from the main tank to avoid transmitting any infection on to the main tank.
Set the tank up as you did the main tank. Filling or half-filling the QT with water from the main tank will ensure that the water chemistry in the QT is similar to that in the main tank. You don’t have to cycle the QT – just take some media from the main filter and add it to the one in QT. Done. Instantly cycled and ready for fish … and no Nutrafin Cycle, Safestart or Stresszyme required.
Once you have the first set of fish in your main tank, all new stock should be added to the QT and monitored for any signs of disease before moving on to your main tank. A minimum quarantine period should be 1 month, but 2 months is much better. The majority of diseases that are present in the water will have had time to show up by then. You’re watching for any signs of illnesses – abnormal growths, fin damage, spots, inflammation and so on. In short, anything that strikes you as unusual.
Some sites suggest that during quarantine, you treat the fish for bacterial and fungal infections, but this is unnecessary unless you find something that really needs treatment. Whenever you’re treating fish – for anything at all, it’s important to remember that the medications used are themselves mildly toxic to the fish. This aside, routinely treating for infections that the fish may not have has 2 adverse effects – 1, the pathogens build up immunity to the medication used, and 2, treating for something the fish may not have brought in with them will only delay treatment if something more sinister presents itself before the unnecessary course is finished and removed from the water.
Once you’re finished with the QT, drain the water, remove the filter and/or its media (some keep the QT filter in the main tank to keep it cycled. Others add the media to the main filter) and clean the tank – no need to use dechloronator for this as maintaining bacteria is not an issue. After that, what you do with the tank is up to you – either store it under the bed, in a cupboard, or, if it’s not in the way of anything, leave it where it is for future use.
So, now you know about the importance of having a quarantine regime in place. It’s not just for the more experienced fishkeepers – it’s for everyone that keeps fish. Some people may not understand the need for a QT, perhaps you've been advised by someone you know that it isn't important but the simple fact of the matter is this: If you don’t observe any kind of quarantine at all, you’re risking the health, and possibly the lives, of all your fish every time you introduce new ones to the main tank.