A Tridacna maxima spawning. Photo courtesy of
Unfortunately, spawning events are very
difficult to predict. Sometimes snails will spawn when they
sense a particular phase of the moon, a sudden or unusual
water condition change (e.g., a large water change), or wide
temperature swings. Often snails spawn if they sense a risk
to their continued survival. The same is true of other organisms
such as sea cucumbers, serpent stars, urchins, anemones, Tridacna
clams and potentially, some corals. Sometimes no particular
stressor can be determined, and it may be a credit to the
aquarist that he has steadfastly maintained a marine organism's
health for years, enabling it to grow to an age at which it
is capable of reproduction. Spawning is a natural and often
fascinating event in an aquarium, but the spawning of large
organisms in a small, enclosed system can cause problems.
A rapid decrease in the water's dissolved oxygen level can
result, as the sudden influx, and subsequent bacterial degradation
from the finely divided eggs or sperm, occurs. Snail spawns
do not usually contain sufficient biomass to overwhelm the
average tank. However, large clams, anemones, corals or the
simultaneous spawning of several organisms might be enough
to drive dissolved oxygen levels dangerously low, even in
a tank with a large skimmer and good water motion. If a large
spawn is detected by an aquarist, having a good canister filter
on hand that can be charged with some diatomaceous earth for
very fine filtration, or activated carbon, can help. The fine-particle
filtration will remove the suspended organic particles from
the water, minimizing the dissolved oxygen depletion that
would otherwise occur as bacteria in the water column consume
these nutrients. There may also be miscellaneous organic chemicals
released during a spawn, or secondary organic chemicals formed
as the materials from the spawn are broken down by bacteria.
Activated carbon can help to bind and remove some of these
organics in the water. In the event of a major spawning, it
may also be advisable to add a working air pump, and several
airstones to the tank to help maintain high dissolved oxygen
levels. If possible, a large water change should also be performed
if the tank's inhabitants begin to show signs of stress such
as rapid breathing and listlessness.
A Sinularia sp. spawning. Photo courtesy of Skip
An unidentified crab releasing eggs. Photo courtesy
of Jamie Cross.
A Plerogyra sinuosa colony spawning. Photo courtesy
of Kedd Lyttonsmith.
Rapid Tissue Necrosis
Red bugs. Photo courtesy of Ximina's Photography.
High temperatures, heavy loads of suspended
particulates, high organic levels and low water motion are
several of the environmental factors that are thought to result
in an outbreak of RTN, or rapid tissue necrosis. Rapid tissue
necrosis can reduce a beautiful, small-polyped stony coral
(SPS) dominated reef tank to a glass box full of bleached,
tissue-denuded coral skeletons in just a matter of hours or
days. While the causes (e.g. bacterial, viral, auto-immune
related) will continue to be debated, certain procedures can
minimize the probability of this occurrence, and can also
slow or stop its progression. I have found that newly acquired
Acropora seem to be particularly susceptible to RTN.
Thickly branched colonies collected from shallow reef environments
with difficult to recreate strong water motion and high light
levels, seem to be particularly prone to RTN. The conditions
common during shipment, i.e., poor water quality, wild swings
in temperature and low dissolved oxygen and water motion,
may also increase the risk of an RTN event. When introducing
a new colony to a tank I've found it best to pre-dip the coral
for 10-15 minutes in a mixture of 5-10 drops of Lugol's iodine
solution per liter of tank water, or to simply follow the
directions on commercially available iodine-based coral dips.
The dip should be performed in an isolated bath with an airstone
to provide some water motion. The coral can then be given
a quick rinse with tank water to minimize introduction of
the dip chemicals into the tank. Ideally, newly acquired specimens
should also be quarantined in a separate and isolated system
until they are well adapted to tank conditions. Such a quarantine
procedure also reduces the chance of introducing any of the
coral parasites that are apparently becoming
more of a problem in the hobby.
If an RTN event starts to take hold in
an established reef tank with no obvious cause other than
the addition of a new, stressed coral, then as a last resort
the progression of the damage can sometimes be halted by using
tank treatment with the antibiotic chloramphenicol as
described by Bingman (1997). If all else fails, fragmenting
affected corals and saving the upper, healthy branches and
moving them to a quarantine tank may allow these specimens
As when using any antibiotic, proper procedures should be
followed when handling and disposing of chloramphenicol. The
use of a dust mask, disposable gloves and safety goggles is
recommended. Wash all utensils and surfaces exposed to the
drug thoroughly with chlorinated freshwater when done. When
disposing of tank water containing chloramphenicol, Bingman
(1997) recommends treating it with bleach at the rate of ¼
cup of bleach per gallon. This destroys the antibiotic and
any resistant bacteria prior to disposing of the water; it
is extremely irresponsible to dump antibiotics into the environment
Additions of Sand
Adding fresh sand to an established tank can sometimes upset
its environmental conditions. Adding new, fine aragonite sand
that is not rinsed well can cause sudden clouding of the aquarium.
Some corals do not react well to this, and such an upset to
the system has been known to start RTN events. Even very well-rinsed,
fine aragonite sand will tend to cloud a tank. For this reason,
it's best not to add too much sand at once. Stop all water
motion, and lower the sand in large cupfuls to the bottom
of the aquarium. Also, it has been noted that new, fresh,
aragonite sand has a chemically very clean surface. Until
the particles are coated with proteins and other substances
from the water, the clean surface may promote the precipitation
of calcium and alkalinity from the water column, possibly
depressing the levels of these important parameters (Holmes-Farley,
Other Tips for Keeping the Gremlins Away:
Another Pair of Eyes
I highly recommend having an experienced reefkeeping friend
occasionally take a look at any new system. Often a fresh
point-of-view is helpful and within just a few minutes an
experienced aquarist may be able identify many of the potential
sources of imminent disaster in the system.
Stinging Critters, Loose Frags,
Snails & Urchins
With their stunning green fluorescent highlights, Hydnophora
(horn coral) can be really beautiful, but after watching it
literally digest an adjacent coral, hobbyists will be certain
to keep it away from any valuable corals. The same holds true
for other stinging organisms such as anemones. Snails, hermit
crabs and particularly, certain sea urchins have a nasty habit
of knocking that "Limited Edition" Superman's Best
Friend's Nuclear Kryptonite Red Acan Lord with Electric Blue
Polyps into your 10-year-old brown frogspawn coral, which
may reduce it to a bare white skeleton in a matter of hours.
SECURE ALL FRAGS! When acclimating a coral fragment to a tank
and slowly moving it to brighter light, consider mounting
it with some epoxy or Super Glue temporarily to a heavy
rock that's difficult for urchins to move. When the coral's
final position is determined, pop it off and securely mount
it permanently in the rock structure.
This brownish plating Montipora was leaning against
this green Hydnophora hard coral for only a few
hours. The Hydnophora is extending mesenterial
filaments, allowing it to literally digest the Montipora.
By the morning, when the filaments have finished their
job, there will be a one- to two-inch band of the Montipora's
tissue completely gone. Nothing but white skeleton will
Corals on the Sand
Certain corals naturally do well simply placed on the sand.
If a sand-moving fish (e.g. a sand sifting goby) or invertebrate
(e.g. a pistol shrimp) is added to the tank, carefully monitor
the new critter until its habits are understood. In a matter
of hours some fish can bury a coral sufficiently to initiate
a bacterial or protozoan infection on the coral that may be
very difficult to halt.
Sea Apples (Paracucumaria
sp. & Pseudocolochirus sp.)
Some species of sea apples can be toxic to fish; either don't
get one, or else consider all the fish in the tank as expendable
at any time.
Rocks on Tank Bottoms
All structural rock in a reef tank should be placed directly
on the tank's bottom, or on some stable support. Do not put
down a layer of sand before building the rock structure. Otherwise,
as the sand shifts or critters move it about, a rock slide
may occur that can damage many corals. If a particularly high
stack of heavy rocks are used in the aquascaping of a glass
tank, it might be advisable to distribute the weight over
a large portion of bottom using inert plastic cushioning material
such as Starboard®.
Water Splashing Fish - Electrical
I have had two powder blue tangs (Acanthurus leucosternon)
with the annoying habit of splashing water about the tank.
The fish rapidly swims the tank's entire length near the surface,
and then flicks its tail as it reaches the end, splattering
water over the light fixtures, and sometimes out of the tank.
One fish splashed so much water that it shorted out an electrical
outlet near the tank. With fish that have this tendency (some
triggers may also do this to get attention/treats), be certain
to take precautions to make ensure saltwater does not make
it to the electrical receptacles. Such precautions include
using drip loops with electrical cords, and covering outlets
with plastic sheeting as necessary. Also consider designing
the hood of the tank to minimize the potential for splashes
to make their way out of the tank.
If new people are cleaning the part of the home where the
tank sits, during their first few visits, or anytime they
add someone new to their team, it is advisable to instruct
them not to use any cleansers near the tank, and in general
to keep an eye on the way they clean. Be particularly wary
of the use of aerosol sprays of toxic cleaning fluids used
in the vicinity of the tank. Is there any chance they might
bump a critical piece of equipment? Any chance they might
unplug tank equipment when plugging in cleaning tools?
Household Pets Around the Tank
Be certain that any pets that can easily jump do not end
up swimming in the tank or sump. Cover the tank or sump if
necessary. Installing some plastic egg crate across tank openings
might also keep pets out. While it might not significantly
affect the tank, the loss of a beloved pet to drowning would
Foreign Objects in the Tank - Children
Be certain that there is no chance that a child could drop
some object or solution into the tank that might prove to
be toxic. If a coin, battery or some such corrodible object
were tossed into a tank and not noticed, the result could
be a slow (or fast) decline of the tank that might be very
difficult to diagnose and rectify. Consider the use of child
proof locks on the doors to the area housing the sump, and
possibly for any doors that allow access to the top of the
tank. For children that are old enough, attempt to educate
them on the harm that could come to the animals in the tank
if foreign objects ended up in the water. There is also value
in educating children to come find you if they think there
is a chance something might have gotten into the water by
accident, or if they see something wrong in the tank (low
water level, fish acting strange, etc.). Keep an eye on neighborhood
children that might be visiting and do not know about what
could hurt the animals in the tank.
Remember the rule that old, salty reefkeepers live by: Any
change; any new reefkeeping technique; a new additive or new
piece of equipment; a change in lighting, water motion or
temperature; or the addition or removal of livestock, rock
or sand, should be done slowly. The results of any changes
made should be carefully evaluated by observing the reaction
of organisms in the tank, and also by monitoring the tank's
chemistry using test kits, if appropriate. It's a good idea
to jot down observations, test kit readings and any corrections/changes
made to the system in a log book for future reference. It
will then be easier to say, "Oh, yeah
with 'X' started just about the time I began using 'Y.'"
While certainly not proving that 'Y' caused 'X,' the knowledge
of the coincidence might help with investigating the problem.
Double-check any unusual results from a test kit. Some values
that I've seen quoted by hobbyists are, quite frankly, chemically
impossible in a reef tank. Look at the critters in the tank,
and if they look okay, chances are that nothing is very far
off. Check expiry dates on your test kit's reagents and make
sure they are all fresh; often, odd readings can be traced
to old reagents. Perform any test at least three times and
average the results, this will reduce the impact of imprecise
Don't go overboard dosing chemicals, as more is not necessarily
better. If calculations suggest the addition of a very large
amount of some chemical, consider having someone review the
calculations or double-check them with an online
calculator. Dose over a few hours or days, and observe
the organisms' reactions. Remember, taking the chemical out
of the water is a lot harder than putting it in.
"Frag" it Out and Spread
I still hear of aquarists who have their main tank crash
for some reason and who moan about how this coral or that
coral are "irreplaceable." News flash: the corals
we grow are capable of nearly infinite vegetative propagation.
Take a fragment of EVERY "irreplaceable" coral and
give it to an experienced reefkeeping friend. He'll likely
share some of his fragments, adding to each other's coral
diversity in case something goes wrong. The same goes for
those who have multiple tanks. If space is available, put
at least one tiny fragment of every "irreplaceable"
coral into a completely isolated system, preferably on a different
electrical circuit. When the next wave of nasty, chemical-resistant,
Acropora eating "monsters from the deep"
sweep through the hobby, this isolated tank will contain the
new seeds to re-populate the system.
Preparing for an Extended Absence:
1. Tank Sitter: Whenever I go away
on vacation I always have someone stay at the house and
look over the tanks. I try to have an experienced reefkeeper
house sit. So many things can go wrong with a tank (particularly
with all my homemade, jury-rigged systems) that I need someone
who knows how healthy corals look and who has some ability
to troubleshoot the system. I always have my tank sitter visit
prior to my trip so I can show him how my system is plumbed.
This visit also allows me to point out the system's known
weak points so he can make a special effort to check these
more frequently. If an experienced reefkeeper cannot be found
to tank/house sit, or if a significant other will be doing
the watching, it's a good idea to have a local expert standing
by who can be called or possibly can rush over to help in
an emergency. Try to leave simple fixes and written instructions
for how things work. For instance, if something goes wrong
with a calcium reactor, it might be best just to inform the
tank sitter to close valves A, B, and C (they should be labeled),
and to start dumping in "X" mL per day of a two-part
calcium and alkalinity solution. Attempting to troubleshoot
a complex piece of equipment over the phone with someone who
does not already understand how it functions is likely to
lead to disaster, or at a minimum, can be quite a strain on
the relationship (be certain to hide all the jugs of bleach
before you leave!). Frequent trips away is one of the best
reasons to join a local reef club, for this is where you will
find the best people to look after your tank while you are
2. No New Plumbing: Never install any new plumbing
or bring a new system on line just before an extended absence.
Be careful not to over-tighten bulkheads or plastic fittings.
Work all the bugs out of any new system or device many weeks
before leaving on a trip.
3. Check Levels Before Leaving: It's a good idea to
make sure that parameters such as alkalinity, calcium and
magnesium levels are all in their proper ranges before leaving
for any length of time. It's also best to perform the testing
at least a few days before leaving so that any necessary dosing
can be done slowly. The last thing anyone wants to do is to
shock the tank with a chemical adjustment (or mistake) just
before leaving for an extended period.
4. Backup Circulation Pumps: Have a backup circulation
pump standing by. Ideally, the pump should have all the fittings
already installed so that installation is as simple as closing
a few valves and opening a union fitting or two. Let a tank
sitter know where the aquarium tools are located.
5. Have Water Standing By: Have saltwater prepared,
aerated and heated, ready to replace at least 20% of the tank's
volume in case of some disaster. Time may be critical if something
goes wrong in the tank. Trying to talk someone through the
proper preparation of saltwater over the phone, or waiting
for an RO/DI system to make additional water, is out of the
question. If different reservoirs are used for saltwater and
RO/DI water, clearly label them so that, in the rush, a water
change is not accidentally performed with freshwater.
Have saltwater and freshwater standing by, and clearly
labeled, in case they are needed in an emergency. This
is particularly important if you are having someone
watching your tank while you are away.
6. Extreme Overfeeding: Be sure to explain how much
to feed the fish. It's a good idea to label a small
bag for each day's worth of food. Sometimes I hide all
the extra fish food so that there is no chance of overfeeding
while I'm away.
I hope this series has been both informative and enjoyable.
Don't put off adding any necessary safeguards. Finally, if
something goes wrong and is luckily caught before a disaster
occurs, learn from the experience. Be a detective and track
down what happened. Whatever is learned and corrected may
ultimately save livestock from a future visit from Murphy.