The Salty Side: Saltwater Aquariums for Beginners

A Simple Guide on How to Quarantine Saltwater Fish

Unfortunately many underestimate how important it is to quarantine saltwater fish before adding them to their main aquarium.  Not going through this process can not only end up wasting you a lot of money but most of all, not giving fish the best possible chance of survival.  We have a moral obligation to take care of them as they are taken from the ocean for our enjoyment.  

Taking your time when choosing new fish at a pet store can greatly increase your chances of success with buying a health fish.  A healthy looking fish should be swimming well showing no signs of lethargy, lopsidedness or disease.  It should have clear skin with no patches of scales missing.

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Why are fish quarantined?

Saltwater fish are not only quarantined to prevent passing on any diseases or parasites to the other fish in the aquarium but to give them the best chance of survival when adding them to your main reef tank.

These fish have more than likely been caught in the ocean, transported to an importer and then survived the journey to your country.  They are then sent off to wholesaler who provides pet stores with their stock.  We then buy them from a pet store and take them home.  If nothing else, these fish need to recover for an extended period before having the energy and strength to cope with being put into a main display tank.  

When fish are stressed, their immune systems are weakened.  If they are then added to a tank that may have a disease or parasite, then their chances of them having the ability to fighting it off are not very good.  They may also end up succumbing to tank bullies who can be quite ruthless in establishing their dominance to a newcomer.  

Another reason to quarantine fish is to get them used to your tank’s parameters and the type of food you feed your fish.  Sometimes you may have to try a few different types of food, frozen, dried etc. before coming across something they will eat but  with a bit of persistence, they should start eating the food you feed in the main tank.

What do I need to quarantine new fish?

1. Small Aquarium

A 10 gallon (35-ish litre) tank should be the minimum size for quarantining saltwater fish.  You can change the amount of water used in the tank if necessary.  So more water for larger fish or a larger quantity of fish or less water for smaller or less quantity of fish.

2. Heating

A 100 watt submersible heater suitable for saltwater aquariums.

3. Lighting

This does not have to be a large, expensive outlay by any means.  A simple LED light will do for a qt tank because the fish won’t be in there for a long period of time … hopefully!  It is important for you to be able to have a good look and see what condition the fish are in.  You need to see if they are actually eating the food you are providing them and that you are able to spot any effect of diseases and parasites, such as ich/white spot (Cryptocaryan irritans).  
If however, you have placed your QT tank in from of a window with plenty of light coming through, lighting will not be required.

4. Filter

A sponge filter, such as the one below, is sufficient for use in a quarantine tank.  This requires forethought though. It is always a good idea to leave the sponge sponge in your sump or refugium of the main tank for at least two weeks before being transferred to the QT tank.  The reason for this is that it allows beneficial bacteria to populate the sponges which helps with the breakdown of ammonia and nitrites in the absence of live rock filtration. 

However, if like me you have somehow forgotten to pre-populate the sponge, all is not lost! There are other ways to safeguard you new acquired fish against deadly ammonia poisoning. My favourite is Poly Filter, which I cut to size in place in the filter. This will continually remove organics and ammonia from the tank. Another go to product is Seachem Prime which you would dose according to instructions.

5. Thermometer

As a QT is generally smaller than the main tank, it’s temperature can fluctuate quite quickly.  It is important to have a reliable thermometer to keep an eye on the water temperature.

6. Hiding Spaces

PVC piping creates great places for fish to hid and destress.  Live rock and sand should not be used as there may be parasites taking refuge in them, defeating the object of the quarantine process.  Parasites would have the perfect opportunity to take hold on a stressed or already disease struck fish.  

PVC piping can be bought at any home depot store. 

7. Ammonia Test Kit/Badge

It is imperative to test ammonia levels regularly as a quarantine tank is only a temporary setup and has not gone through the proper cycling process.  This can be done with a test kit, or by using an ammonia level display such as Seachem Alert  

How to quarantine saltwater fish

Ideally the quarantine tank should be set up a few days before acquiring new fish.  This will allow you to monitor and adjust the parameters should they need changing. 

It should be in a quiet area or an area where fish won’t feel constantly threatened, for example people or pets making sudden movements near them.  You can place a screen around the quarantine tank if necessary as the aim is not to stress new purchases any more than they already are on arrival.

Water to fill up the qt tank could be used from the main reef tank.  You can do this over a period of a few days, topping up the main tank with fresh saltwater as you go. It could also be newly mixed saltwater.

A Tang covered in Ich (White Spot)

The quarantine tank shouldn’t have anything else added, apart from a hiding place that the new fish can take refuge in and essential items such as the filter, heater etc.  Giving them a place to hide will allow them to recover.  A great analogy here is … You’ve just taken a bunch of kids, yours or others, to soft play on a Saturday afternoon.  If you’re anything like me then you need to quarantine yourself for the rest of the weekend never mind the evening! 

The new fish will also need to be acclimated before adding them to the qt tank.

How big should a saltwater quarantine tank be?

A 10 gallon (45 litre) tank should be plenty big enough for quarantining most fish, but if your fish are of the larger variety you may need to go bigger.  As mentioned previously, you could use a larger tank (20 gallon – 90 litre) but you don’t need to fill it right to the top unless you want to or need to. 

How long do you quarantine saltwater fish for?

Saltwater fish should be quarantined for a minimum of 21 days.  This is because most parasites take this long to complete their life cycle.  Some fish may not immediately show signs of pests or diseases.  They might have only caught it at the pet store which means they might not yet be showing signs of infection.  This is where problems often occur because if you added the infected fish directly to your main tank, it could end up infecting ALL your fish.  And that is a problem a lot harder to solve especially if you have coral and invertebrates to take into consideration.  

This length of time also gives new fish a good chance of building up their immunity by destressing and for us to make sure they are eating properly and are generally as healthy as possible before adding them to the main tank.

Do you feed fish in quarantine?

It is recommended that fish are fed twice per day, once in the morning and once in the evening.

If you have tangs in the quarantine tank then you can also feed them nori.  This can be either clipped on the side of the container using a clothes peg or by using a nori clip or holder. 

So there you have it!

Quarantining saltwater fish is highly recommended.  It may feel like a long time but you’ll be glad you did.  Adding fish that have recouperated from their stressful journey from not only pet store but the ocean, will give them a much higher rate of survival and less chance to infect the inhabitants of your main tank should they be carrying any pest or diseases. 

It is also a good idea to quarantine any invertebrates and coral purchased from pet stores or other reefers.  (Don’t forget to acclimate invertebrates!)  It is as easy for parasites to hide in coral or on a shell as it is to hitchhike on a fish. 

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