DK ENCYCLOPEDIA AQUARIUM AND A POND FISH

50 ● F R E S H W A T E R F I S H : M A I N T E N A N C E

Routine tasks

A well-set-up tank that is functioning properly will only require
a minimal amount of time spent on its maintenance.The
aquarium should develop into a stable ecosystem, in which
toxin levels are kept in check as part of the natural
cycle.With regular checks and a few simple
“housekeeping” tasks, such as partial water
changes, your aquarium will look its best
and your fish will stay healthy and content.

Regular partial water changes ensure that toxic chemicals do Emperor tetras (see p.100) are very sensitive to accumulations of
not build up in the tank and harm the fish.They should be nitrogenous compounds in the tank water. Regular partial water changes
carried out once a month or when indicated by water test are therefore especially important for the well-being of these fish.
results (see p.46). Start by turning off the power to the tank.
Fill a length of siphon tube (see box, opposite) with tap water, the bucket; water should flow from the tank into the bucket.
adding a drop of water conditioner to dechlorinate it, just in A gravel cleaner can be attached to the end of the siphon tube;
case any should escape into the tank.With a finger over each as you move the cleaner over the substrate, the water flow stirs
end of the tube, place one end in the tank and the other into a up the gravel and sucks out particulate waste.When you have
bucket. Release the tank finger first, followed by the finger in removed enough water, simply lift the tube out of the tank.

REGULAR MAINTENANCE TASKS

DAILY WEEKLY MONTHLY

● Check the thermometer; if the water ● Carry out water tests to monitor levels of ● Carry out a partial water change—
temperature has changed, the heater or the nitrogenous waste. Keep a check on the pH approximately 25 percent of the functional
thermostat may be faulty. as well, using either test kits or a meter. tank volume—using a gravel cleaner as well.

● When feeding the fish, watch out for any ● In a newly established aquarium, carry ● Trim dead stalks and leaves from plants.
decline in appetite, since this is usually a out a partial water change of up to Add aquarium plant fertilizer to the water.
sign of illness. 20 percent every week, since the filtration
system will not yet be fully functional. ● Remove any buildup of algae in the tank
● Check the lights above the tank; replace by cleaning, and then adjust the period of
a burned-out tube without delay. ● Check for any change in the appearance light exposure within the aquarium.
or behavior of the fish that may indicate
● Make sure the filter is working effectively; that they will soon be breeding. ● Where an internal power filter or an
if it is not, there may be a blockage in the external filter are being used, strip down,
system or even a power failure. ● Siphon out any mulm accumulating on check, and clean the filtration system.
the substrate. This will reduce the burden
● Reposition any substrate plants that have on the filtration system.
become uprooted and floated to the surface.

R O U T I N E T A S K S ● 51

Long-handled algal scrapers
are invaluable for keeping the
sides of the aquarium free of
algal growth, enabling you
to reach right down to the
base of the tank. Magnetic
scrapers use a short handle
on the outside of the
glass to control a scraper
blade on the inside.

Algal overgrowth Some algal growth can be
on aquarium plants is beneficial to fish, because it
not only unsightly, but can forms part of the natural
also prevent them from diet of a number of species,
photosynthesizing, which including this Electric Blue.
will cause them to die back.
Problems with algae
Before refilling the tank, add a suitable amount of water Excessive algal growth may occur if the aquarium lights are
conditioner to the fresh water, and make sure that it is at left on for too long. It is especially likely if there are no plants
the same temperature as that within the tank, or the fish will in the tank, or if the plants in a new tank are not yet fully
be stressed by the sudden change. Pour the water in slowly, established, because plants naturally compete with algae for
taking care not to disturb the roots of the substrate plants. nitrates and other key growth compounds in the water.
Without competition, algae spread more easily, not only
If your tank has a biological filter, switch the power back growing on the glass but also covering rockwork and other
on as soon as possible, because the aerobic bacteria that
provide the basis for filtration will die if they do not receive
oxygenated water for some time. Should you need to replace
the filter sponge, be sure to add a seed culture of bacteria.
Be prepared for an initial deterioration in water quality, since
the biological filter will not work efficiently again until the
bacteria have colonized the surface of the new filter sponge.

PARTIAL WATER CHANGE

Cleaning the gravel while siphoning
water from the tank improves the
filter’s efficiency and ensures that
the gravel bed does not
become compacted. Save
the tank water that you
siphon into the bucket;
you will need this to
rinse the filter sponge.

Cleaning the filter sponge ᕡ Siphon out the water ᕢ Clean the gravel

Rinse out the sponge in water Place the bucket below the tank to ensure a good Take care not to uproot any substrate plants when
taken from the tank, to remove flow. Never suck water through the tube to start using a gravel cleaner.The water flow will not be
any debris that has collected. the flow—you could swallow harmful microbes. strong enough to suck gravel up the tube.

52 ● F R E S H W A T E R F I S H : M A I N T E N A N C E

tank decor. Reducing the length of time that the aquarium nitrite poisoning when this chemical is present in concentrations
lights are on will help to curb this problem, as will making of just 0.5 mg/liter, whereas most other fish will be unaffected
regular partial water changes (which keep the nitrate levels until the level rises to 10–20 mg/liter. Ammonia can be
low) and introducing fish that browse on algae. removed by the chemical zeolite, which is either added to the
filter (if present) or simply dropped into the water.
Monitoring water quality
Test kits and meters (see p.46) should be used to make weekly NEW TANK SYNDROME
checks on the water quality. Daily visual checks are also vital;
any unexpected change in the appearance or behavior of your Water conditions in a new tank take time to stabilize. There is an
fish may indicate that there is a problem. For example, if the initial rise in the level of ammonia, which the fish excrete as waste.
gills of a fish become brown instead of the normal pink, it is As the biological filter starts to work, beneficial bacteria break down
likely that there is too much nitrite in the water.This will the ammonia into slightly less harmful nitrite, which is eventually
interfere with the ability of red blood cells to carry oxygen. converted into nitrate. Although this is called new tank syndrome, a
Regular partial water changes will usually cure nitrate excess. similar situation can arise in a mature tank if the filter’s efficiency is
A rise in the level of nitrite or toxic ammonia may be due to dramatically reduced. This could be caused by the use of antibiotics
“new tank syndrome” (see right), caused by overfeeding on a (which will kill the bacteria), a breakdown in the oxygenation of the
regular basis (see p.49), or a result of overstocking the tank, filter bed, which is essential for the survival of these aerobic
which places extra demands on the filtration system. microbes, or simply the replacement of the filter sponge.

Fish differ in their susceptibilities to dissolved chemicals, Level (mg/liter) 11 The rapid initial
which is often a reflection of their habitat in 10 peaks of ammonia
the wild.Those occurring in fast-flowing 9 Ammonia Nitrite and nitrite in a new
water where there is little opportunity 8 tank are followed by
for pollutants to accumulate, such as 7 a slower climb in the
discus (see pp.142–3), are much more 6 nitrate level. It takes
vulnerable than those that naturally inhabit 5 about seven weeks
small ponds. Discus show obvious signs of 4 for a biological
3 filter to become
2 fully functional.
1
0 Nitrate

0 4 8 12 16 20 24 28 32 36 40 44 48
Time (days)

The stocking density of the tank VACATION ISSUES
has a direct impact on the efficiency
of the filter. The larger the number ● Arrange for a friend or
of fish, the more difficult it will be neighbor to check the tank
for the filter to deal with their every day in case there is a
accumulated waste (see p.30 power failure or any of the
for more on stocking densities). equipment malfunctions.

● If someone else is to feed
the fish, show them exactly
how much food they should
give each time, in order to
prevent overfeeding.

● As an alternative, consider
using an automatic feeder
or a food block.

● Carry out a partial water
change and check all the
equipment before you leave.

● Leave a contact number
in case of emergencies.

FRESHWATER FISH

ILLNESS AND
TREATMENT

54 ● F R E S H W A T E R F I S H : I L L N E S S A N D T R E A T M E N T

Health concerns Eyes are bright Body appears plump,
and must rather than saggy
Fish are susceptible to a wide range of bacterial, viral, not appear
fungal, and parasitic diseases.The artificial conditions swollen Scales evenly cover the
in the aquarium tend to concentrate the risk of disease body and must lie flat
and increase the speed at which illnesses spread,
because fish health is strongly influenced by the quality Gill movements Fins and tail
of the environment. Early intervention can head off may increase should not
many of the most common conditions, but, as with under stress normally be
humans, prevention is always better than cure. ragged at
A healthy fish appears active and feeds well. This Cockatoo the edges
Dwarf Cichlid (Apistogramma cacatuoides) demonstrates
what to look for in a well-kept specimen.

Minor injuries, such as the rip in Fungal infections are opportunistic, Risk factors
the dorsal fin of this corydoras lurking in the tank and invading at
catfish, can provide an entry point sites of injury. If untreated, they spread A fish housed alone is less likely to succumb to illness than
for life-threatening infections. fast and may kill the fish. one in a community aquarium because it is not subject to
bullying by tankmates.This often causes minor injuries, such
Get to know your fish as damaged fins and scales, which may then become infected.
Aggression usually increases at the beginning of the spawning
Most common diseases of aquarium fish are treatable, period, so a close watch should be kept on fish at this time.
provided they are identified in their early stages. Later in
the course of a disease, obvious symptoms, such as major The greatest risks to health occur when fish are introduced
color changes or large parasites, will become apparent, to the aquarium. New acquisitions should be held in a simple
but it may be too late for successful intervention.The best isolation tank for two weeks before transfer to the main tank,
strategy for disease prevention is therefore close observation; by which time any serious health problems should have
knowing how your fish look, feed, swim, and interact with emerged.With new fish, it is often helpful to remove all the
others allows you to spot subtle changes in appearance and occupants from the tank, rearrange the tank decor, then
behavior that may signal stress or the early stages of disease. introduce new fish together with the previous occupants.
This strategy significantly reduces outbreaks of bullying.
If you suspect that a fish may be ill, check the tables on
pages 56–8 and attempt a diagnosis. If in doubt, consult an WHITE SPOT White spots on the
expert at your local aquarium store. Move the affected fish fish’s body contain
out of the main tank into a hospital tank (see opposite) for Tomites in the mature protozoan
further observation and treatment.This will isolate the fish water find new parasites
from its tankmates and prevent cross-infection. Always check fish to attack
the quality of water in the tank; dirty or unbalanced water The spots rupture,
may cause illness directly or put the fish under stress, so The cysts break releasing parasites
predisposing it to attack by pathogens that may already be in open, releasing into the water
the tank. Most healthy fish carry a natural burden of parasites, tomites into
but environmental stress may lower the immune resistance of the aquarium
the fish and allow the parasites to multiply.
Each cyst can Parasites
produce up to 1,000 form cysts
tomites, which are
the free-swimming Cysts sink and attach to
form of the parasite the aquarium floor

Protozoan parasitic infections, such as white spot (also known as “ich”),
spread fast within the aquarium. The life cycles of the parasites are
completed rapidly and thousands more can be produced in a single cycle.

H E A L T H C O N C E R N S ● 55

Effective treatments ISOLATION AND MEDICATION

The effective commercial remedies now available treat the In some cases it is desirable or essential to treat a fish in a separate
great majority of tropical fish conditions; a knowledgeable hospital tank—a relatively stress-free environment where sick fish
retailer should be able to guide you to the most suitable one. can recuperate. This should be a small tank (about 12 gallons or
The treatment may be given in the home tank, in a stripped- 50 liters) containing no living plants, but with a simple filtration
down hospital tank, or in a small bath. Carefully follow the system, and perhaps a flowerpot or plastic plant as a refuge.
instructions given on the medication. Overdosing is likely to
be harmful, especially for a fish already weakened by illness; Using a hospital tank
similarly, do not stop the treatment earlier than advised if the to quarantine new fish
fish seems to be recovering. Remember to dechlorinate any before transferring them
water used to make up treatment solutions and make sure it to the main tank is a
is at the same temperature as that in the main tank, in order sensible way of reducing
to lessen the stress on the fish. the risk that you will
introduce diseases to
If an outbreak of unspecified disease occurs in an your other fish.
established group of fish (rather than in one individual that
can be isolated from the group), regular partial water changes Simple filter in hospital tank
will always help, because they lessen the concentration of
disease-causing organisms present. Eyedropper

Some illnesses simply defy treatment. If you need to kill a Main tank
fish painlessly, carefully cut through the spinal cord behind the
head with a sharp knife or take it to your veterinarian. Never Glass cover prevents
be tempted to flush a fish—living or dead—down the drain. fish from jumping out

Home test kits include a wide variety A small glass dish can be used Methylene blue is a traditional
of chemical analyses that can be to give concentrated medication— remedy used for a range of
carried out to identify almost any for example, to remove external ailments. It will, however, stain
problem associated with water quality. bacteria, parasites, and other silicone sealant, and should never
disease-causing organisms. be added to the main aquarium.
The design of the aquarium
itself is influential in keeping
the fish healthy. A well-
planned tank provides retreats
for shy species, and lessens
the risk of bullying in more
territorial species.

HUMAN HEALTH

● Switch off the power
before placing your hands
in the water.

● Always wear a pair of
rubber gloves when coming
in contact with tank water.

● Never try to create a flow
of water through a siphon
by sucking it.

● Don’t dump dirty water
down the kitchen sink; use
an outside drain if possible.

56 ● F R E S H W A T E R F I S H : I L L N E S S A N D T R E A T M E N T

DIAGNOSIS OF COMMON PROBLEMS The tables on the following pages will help you diagnose the most
common conditions affecting freshwater species, and point you toward
It is not always easy to distinguish between the different ailments appropriate treatments. First, in the table below, identify the part of the
that can affect tropical fish, especially in their early stages. Diagnosis fish’s body that appears to be affected. Next, find the signs of illness
may be further complicated by the fact that more than one infective that most closely match those displayed by the fish. Note the number(s)
agent is often responsible for the visible symptoms. For example, associated with the relevant signs, and refer to pages 57 and 58 for a
when a fish develops white spot (see p.54), bacteria and fungi may fuller description of the possible conditions and their treatment.
gain access to the body at the site where the parasites initially
attacked, confusing the diagnostic picture.

EYES SIGNS OF DISEASE • One or both eyes missing from their sockets, with no other
SKIN obvious physical symptoms or behavioral abnormalities ቢ
FINS • One or both eyes appear to be bulging abnormally from their
COLOR sockets ቦ ቪ ቮ • Area around the eyes becomes abnormally white ቪ

• Bulging eye or eyes, accompanied by loss of appetite and • Eyes develop a glazed appearance, and the fish has difficulty
color change ቢ co-ordinating its movements

• One or both eyes have a cloudy appearance in the central
pupillary area ቢ

• Skin loses its color, becoming paler than normal, and the fish • Skin has a more slimy appearance than normal ቯ ቲ ታ ቴ
appears less active than usual ቱ ት ት

• Growth resembling cotton fluff appears on an area of the • Straggly pieces resembling cotton appear to trail down from
body or on a fin ቤ ቨ the sides of the body ታ

• White, pus-filled pores develop near the head, becoming • Strangely shaped blemishes become evident on the sides
ulcerated. Whitish feces may hang from the body ተ of the body ቧ ታ

• Fins develop an abnormally ragged appearance, especially • White spots appear over the surface of the fins as well as on
evident in the caudal fin ባ the body ቯ

• Red streaks start to develop in the fins, which appear to be • Fins are clamped down against the body, making it difficult for
congested with blood ባ ቦ the fish to swim normally

• Areas missing from the fins; especially evident in fish with • Splits develop in the fins, vertically in the dorsal fin and more
unusually long fins horizontally in the caudal fin

• Fish becomes paler in color and loses its appetite ቱ ት • Body color alters, with markings appearing less well-defined
than normal ቢ ቯ ቲ ታ ቴ ት
• Reddish areas become evident on various parts of the body,
including the mouth, anal region, and bases of the fins ቦ ቧ • Pale areas develop on the head ተ

• Body develops a yellowish-gray cast, which extends to the fins • Eggs develop an abnormal cloudy, milky appearance, especially
as well as the body ቴ if infertile ቩ

SHAPE • Abdominal area swells significantly, to the extent that the fish • Surface of the body erodes, forming ulcers ቦ ቧ ቯ ተ ታ ቴ
BEHAVIOR has difficulty swimming ቢ ቮ
• Fish’s profile alters, with its belly area starting to bulge
• One or more unusual swellings appear anywhere on the noticeably upward, indicating emaciation ቢ ተ
surface of the fish’s body ቪ ቲ

• Fish undergoes a progressive loss of weight, in spite of the fact
that it appears to have a healthy appetite ቢ

• Fish starts to spend longer than normal at the surface of the • Loss of appetite, with the fish becoming less active, and lying
tank, sometimes hanging there at an abnormal angle ቲ ቶ on the floor of the aquarium ቦ ቧ ቪ ቫ ቭ

• Gill movements become very apparent, causing the fish to • One individual starts to be picked on by other fish in the tank,
appear as if it is gasping ቴ ቶ and starts to hide away ቢ ቱ

• Fish starts to rub itself against rockwork and other objects in • Fish begins to swim at a strange angle in the tank, sometimes
the aquarium ቯ ቲ ታ ቴ ት even upside down ብ ት