Two frequent posts
on marine aquarium based forums are along the lines of:
|"I just put a new fish
in my reef tank and it hides all the time and isn't feeding."
|"I just put a new fish
in my reef tank and now all my fish have little white
In most cases, the new fish has been placed
directly into the main display tank and then things go downhill
from there. These two common problems and others can be solved
by first placing all new fish into a quarantine tank.
Why will quarantine help? I believe there
are two main reasons to quarantine ALL new fish:
|| Acclimatizing fish to
life in captivity
While the second reason is the one that
comes to most people's minds first, I'd like to spend some
time on the other as I feel this is more important.
Consider what happens to a fish you buy
from the time it is caught until the time you bring it home.
||The collector catches
the fish and places it in holding tanks.
||The fish may actually
be placed in a temporary holding tank at the collection
site and then moved to the collector's main facility on
||It may spend anywhere
between a day and a couple of weeks in these holding tanks.
||It may then go to a distributor
where it will be placed in another holding tank.
||Eventually, it will be
bagged up and flown to the Local Fish Store (LFS) and
it may be in the bag for over 24 hours before it is released
into the tank at the LFS.
The time, from capture to the LFS tank,
may be two days to over two weeks and in this time it is unlikely
that the fish has been fed.
At the LFS, the fish may get some food,
but as the LFS has many fish to worry about, this fish won't
get any special treatment. As the fish was wild caught, it
won't be accustomed to eating prepared foods and may not even
take food that is floating.
You are now on your way home from the LFS
with a fish that has been highly stressed for anywhere between
days and weeks. It probably hasn't eaten and is likely to
What's going to happen if it is placed
in your main display tank with a bunch of healthy fish that
will eat anything dropped in front of them?
More than likely it will hide. It probably
won't get much of the food added to the tank as the other
fish will get the food first. If it needs "training"
with live foods, it will have to compete with the existing
fish. There is also a real danger that the existing fish will
harass it or even fight with it.
The alternative is to place this new fish
into a tank on its own. The tank would have sufficient hiding
places and you could dim the lights to lower stress. Most
importantly, you can give the fish one-on-one attention to
get it feeding and this allows you to try a wide range of
foods. Finally, once the fish is feeding, it has a chance
to build up strength and get used to living in captivity.
After four to six weeks in a tank on its own it
should be feeding on a variety of foods. It should have regained
any weight it lost between capture and your tank. It may even
start to grow. Most importantly, it will be under very little,
if any stress.
Disease prevention is another good reason
Fish may carry with them diseases from
the wild or may come in contact with infection in holding
tanks or at the LFS. The most commonly encountered disease
is marine "Ich" which is caused by the protozoan
Cryptocaryon. The life cycle of Cryptocaryon
is two to three weeks, so isolating a fish for four to six weeks greatly increases
the chances of detecting the infection before the fish is
introduced to the main tank where the infection could spread
to the other inhabitants. If disease is detected during the
quarantine period, it can be more easily treated in a smaller
tank without concerns for the effects that medications will
have on invertebrates.
There are other and more severe diseases
such as Amyloodinium which are not only highly contagious,
but are very quick acting. These must be treated immediately
for there to be any chance of saving the infected fish. Having
the fish in a separate tank means that treatment can be administered
immediately without stressing the fish any further.
If the water quality in the quarantine
tank is good and the fish is exposed to little or no stress,
diseases are uncommon and treatment is rarely necessary.
Why Not Quarantine?
Some people argue against a quarantine
tank as they feel it adds more stress. This would only be
true if the quarantine tank is not set up correctly. If there
are insufficient hiding places or the water quality is not
high, a quarantine tank may be more stressful. However, both
of these problems are easily remedied.
How to Set Up a Quarantine Tank
A tank for quarantining fish does not
have to be elaborate. It just needs to be a stable environment
with good clean water and plenty of hiding places for fish.
A quarantine tank should be at least two
feet in length. Anything smaller may cause stress to the new
inhabitant(s). A standard three foot tank would be better
and this provides enough space for most fish. Even tangs and
juvenile angelfish will do fine in a tank of this size for
the quarantine period. My quarantine tank is a standard three
The tank will need a heater and minimal
lighting. A single fluorescent tube should suffice. You can
get by with a standard daylight tube, and there is no need
to use an expensive aquarium type tube.
My quarantine tank. It is 36"
x 14" x 18" with shell grit and an air-driven
DIY undergravel filter. Hiding places are rocks, coral
skeletons and shells. I cannot treat with copper in
this tank, but to date it has not been necessary. I
have used hyposalinity treatment with success.
Careful thought must be put into the tank
decorations. Calcareous materials should be avoided as calcium
carbonate absorbs copper. This causes two problems if treatment
with copper is necessary:
||It will be difficult to maintain the correct
level of copper as the absorption by the calcium carbonate
will take the copper out of solution.
||A drop in pH can cause the copper to be
released back into solution potentially causing lethal
doses of copper.
PVC piping and ceramic pots make good hiding
places, and they can be easily removed when it comes time
to catch the fish. Live rock should not be used, as these
are coral rubble which is composed largely of calcium carbonate.
Additionally, you do not want or need invertebrates in a quarantine
tank as these will restrict treatment.
As most wrasse species bury themselves
in the sand at night, it may be necessary to provide sand
in the tank. Silica sands and non-calcareous river sands should
be used if you plan to keep wrasses.
A quarantine tank needs some form of biological
filtration. The simplest biological filter is a canister filter
with bio-balls. Another possibility is an undergravel filter
using non-calcareous sand. The tank should be cycled in the
normal way, and should not be used for quarantine until the
ammonia and nitrite levels are both undetectable. Under normal
circumstances, this should take four to six weeks. If the
quarantine tank is set up at the same time as the main display
tank, it will have cycled at some point before you would be
putting any fish into the main tank.
The temperature and salinity of the quarantine
tank should be maintained at the same levels as your display
tank. This should be the same as natural seawater in reef
environments: 26-29° C (79-84° F) and 35 ppt.
The process to quarantine new fish is very
The new fish should be acclimated as you
would any fish. First, the bag is floated in the water to
allow the water temperature in the bag to meet that of the
tank. Ten minutes should be plenty of time. Next, gradually
add tank water to the bag. Continually add water until you
have added around four times the original volume of water
in the bag. Since fish are fairly tolerant of changes to water
parameters, this should only take around 30 minutes. Drip
acclimation is usually the simplest method to achieve this.
Fill a 2L (2 quart) container with tank water and siphon water
from the container to the bag using airline with a clamp or
tap such that it drips quickly. This will provide a consistent
progression from the bag water to the tank water.
Some people recommend discarding the water
in the bag by pouring it through a net into a bucket. The
fish is caught in the net and then dropped into the tank with
almost no water from the LFS.
Personally, I don't see the small amount
of LFS water being much of a problem and most pathogens would
be carried on the fish rather than in the water. I'd prefer
to subject the fish to as little stress as possible and so
I allow it to swim out of the bag.
Once the fish is in the tank, it is a good
idea to dim the lights if possible. Don't shut the lights
off completely, as the fish will need to investigate its new
environment and find suitable hiding places. Give the fish
an hour or so to settle in before switching the lights off
for the night.
On the following day, try to minimize your
movements around the quarantine tank so as not to frighten
the fish too much. Carefully observe the behavior of the fish.
You will need to continue these observations for the time
the fish is in the quarantine tank. Look for any abnormal
behavior such as scratching and flaring that might suggest
infection. A small amount of scratching is normal and some
species will appear to scratch themselves on the sand when
looking for food.
On the day after the fish is placed in
the quarantine tank, you need to start to get it to feed.
Some fish will start feeding almost immediately, however,
others may be reluctant to feed or may not know that the food
you provide is food. Be prepared with a number of different
types of frozen foods. You may also need access to live foods
such as Artemia naupii (baby brine shrimp) or adults.
The movement will often pique interest and stimulate them
The fish should be left in the quarantine
tank for at least four weeks. Six weeks gives more time for
observation. A longer time may be necessary if the fish is
not feeding well on a number of different foods or is not
behaving normally. If the fish shows any signs of infection,
the appropriate treatment should be administered.
If after six weeks, the fish is behaving
normally, eating well and shows no sign of infection or loss
of weight, it can be moved into the main display tank. The
acclimation method above can also be used in the main tank.
Quarantine is a very important practice
to ensure a successful marine tank with healthy fish. It ensures
that any fish placed in your display tank is as fit as it
can be and the most prepared for competition from the other
fish in the tank. Additionally, quarantining fish will greatly
reduce the probability of introducing disease into the display
tank. A quarantine tank is very easy to set up and for the
benefits it gives, it is definitely worth the cost and effort.