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Caring for your Fish
(Note: includes non-native fish) Fish are very
relaxing and beautiful to look at and many species are kept for these
reasons. They are suitable pets for people living in flats or other confined
areas, but for people with
plenty of outdoor space an in-ground fish pond
can enhance a garden setting.
Whether kept in an aquarium or pond, a great deal of care is required in
looking after fish properly.
Choosing your Fish
The type of fish you keep will depend on the amount of space you have, and
the amount of money you wish to spend on their purchase and the equipment
associated with their care.
There are two broad categories of aquarium fish; freshwater and saltwater
(marine) - and within each of these categories are coldwater and tropical
varieties. Coldwater fish are suitable for coldwater aquariums but
tropical
fish need heated water; outdoor pond fish are normally of the
freshwater-coldwater type.
Choose cheap fish to begin with (because these are generally the easiest to
keep) and buy only healthy specimens; be sure to purchase your fish from a
reputable dealer (dead fish in the sale tanks indicates poor health).
Beginners should start with a small freshwater aquarium and a few coldwater
fish. Saltwater tanks are more difficult to manage than freshwater. Choose
hardy specimens such as goldfish; there are many varieties of goldfish but
only some are available in Australia. Coldwater marine fish such as leather
jackets, breams and small flounder are also cheap and easy to keep.
Tropical freshwater fish suitable for beginners include platties, sword
tails, guppies and mollies. Be sure that you know how to keep fish properly
before buying tropical fish because they are very sensitive to poor water
quality and temperature fluctuations. Tropical marine fish suitable for
aquariums include clownfish, wrasses and tropical seahorses. Seahorses can
be difficult to feed properly as they often require specialised food.
Never keep incompatible fish together as some may eat others. Also, be
careful with aggressive fish such as Angel fish. They can be very aggressive
towards each other, particularly if the space in the tank is limited. For
advice talk to the pet shop and also contact your local Aquarium Society.
Members are usually very helpful with advise, equipment purchases and
sourcing of suitable fish.
Care for your Fish
Housing
A fish tank should
be an appropriate size for the number of fish held. If a non- aerated
aquarium or outdoor pond is used, allow three centimetres of water surface
area for every three square centimetres of fish (including the tail). A tank
should be rectangular; fish bowls have a small water surface area and
therefore limit the amount of oxygen entering the water. In addition, for
each centimetre of fish you will need about five litres of water regardless
of whether the tank is aerated or not.
It is now useful for glass tanks to be glued together with silicone sealant
rather than having a frame as in the past. If a frame is used, marine
aquariums must be framed with aluminium or stainless steel to prevent damage
to the frame by the saltwater. Either way, the glass from which the tank is
made must be thick enough to withstand the weight of the water.
Freshwater should be allowed to stand in a stainless steel or plastic
container for 24 hours before use, to allow dissipation of chlorine (common
in tap water). Seawater is best made up from bottled water or tap water with
the addition of special sea-water mix available from aquarium shops.
Establishing an Aquarium
Place the empty aquarium and stand on a flat solid surface in a
well-lit position but not in direct sunlight.
Direct
sunlight will heat the tank water too much during the day and it will cool
too much at night and as a
result your
fish will suffer stress diseases. Direct sunlight will also cause too much
algae to grow and the
tank will be
difficult to keep clean.
Remember that one litre of water weighs one kilogram and there is the
additional weight of the tank,
stand and
other equipment. The floor surface you have chosen must be able to support
this total weight.
First, half fill the aquarium with water (clean tap water is
suitable). If a bottom filter is to be used, install it
at this
stage. Then place sand on the bottom with pebbles and stones for decoration
and to provide
hideaways for
the fish. Anchor in some water plants which will help oxygenate the water.
Complete the filling of the tank to within five centimetres of the
top. If you have purchased active fish, or
they
are likely to be disturbed, they may jump out of the tank, so cover the
aquarium with a glass top that
is
raised sufficiently to let air in.
A water filter operated by a small electric submersible motor will
help to keep the tank clean, but if your
fish are
being fed too much food, thus excreting too much, algae will still overgrow
in the tank.
The same motor can operate an aerator that pumps tiny bubbles of air
into the water. These aid in
circulating
the water (which helps with oxygenation, since most oxygen exchange takes
place at the
surface).
Bubbles also show that the filter is working properly. Many filters use a
combination of charcoal
filters and
fine sponge filters to remove solids. These will need to be regularly
cleaned and replaced. You
can stock the
tank with 40% more fish if an aerator is used.
For tropical fish a heater and thermometer are also needed to keep
the water at the right temperature
(22 C - 24
C for tropical and marine fish and 15 C - 20 C for coldwater fish). The
effects of central
heating and
other forms of room heaters should be considered. Water temperature in tanks
should be
checked daily
and maintained within a range of 5 C of the optimum temperatures.
Let the newly filled aquarium stand for about 3-4 days before buying your
fish. Fish are usually sold in a plastic bag and this should be floated on
the surface of the tank water for about 30 minutes to allow the water and
fish in the bag to reach the same temperature as the water in the tank. This
way, fish will not get a shock by being moved to water at a different
temperature. A sudden temperature shock of even a few degrees can kill the
fish. After this time, add tank water very slowly to the bag to allow the
fish to acclimatise to the tank water (and thus prevent osmotic shock). Then
decant the fish into the tank.
New aquariums take about 2 - 3 weeks to 'settle down' after the fish have
been added. During this time tanks should be tested daily for nitrates and
ammonia (using kits which can be purchased cheaply). Nitrates and ammonia
are very toxic to fish, however they are converted to more harmless nitrates
by the action of "nitrifying bacteria". Once the bacteria reach equilibrium
in the tank, they will convert the nitrates and ammonia as it is produced.
The plants use the nitrates in the water.
Change about a quarter of the water every week whether it is dirty or not.
Be very careful to ensure that the replacement water is at the same
temperature as the tank (to within two degrees) If the tank is particularly
dirty replace about 1/3 of the water at once, clean the filter and then
remove and replace a quarter of the water each day until it is clear again.
Carefully monitor the nitrate and ammonia levels.
Never overfeed the fish. Add just enough food for the fish to eat
over a five minute period. Carefully siphon off any uneaten food from the
tank floor.

Establishing an Outdoor Pond
Fish
ponds are best if in-ground and made of cast concrete, although some
prefabricated cement constructions and some butyl rubber liners are
suitable. Where plastics are used, ensure that the supplier warrants them
suitable for use with live fish as many plastics are toxic. The minimum
depth of available water must be 30 cm., but it is wise to have even deeper
sections so that fish can reach cooler water areas. As with aquarium fish,
the number placed in a pond will depend on the surface area of the water and
whether or not the water is filtered and circulated.
Adequate aquatic plants must be placed in the pond to help remove nitrates
and phosphates (which cause algal growth) and to provide shelter for the
fish and a place for eggs to be laid. Algae and plants generate oxygen
during the day, but absorb oxygen at night. On still warm summer nights they
can easily remove all of the oxygen and kill the fish. To avoid this, ensure
that pond pumps run at night when there is no wind to ruffle the water.
Rocks must also be strategically placed to provide both good shelter and for
decorative purposes.
Ponds are best sited out of direct sunlight in order to control algae
growth. Watch for predator birds if setting a pond near large trees. A water
filter system is essential to remove algae and other impurities and the
system should be designed so that one-quarter of the water is replaced each
week this is easily achieved by establishing a deliberate leak in the water
filtration system of appropriate volume. Newly poured concrete ponds, and
new butyl rubber liners should be filled with water and allowed to stand for
four weeks. After draining and cleaning it is safe to refill and stock with
fish.
Feeding
If your fish are kept at a constant temperature in the aquarium you should
feed them every day. Allow just enough food for the fish to feed for about
five minutes. Supply a variety of dried food (flakes), frozen food (brine,
shrimp, daphnia) fresh food (earthworms, tubiflex) and green food (algae and
water moss) all of which is available from aquarium shops. Do not overfeed
fish as the uneaten decomposed food will make the water smelly or clouded
and the fish will die.
Pond fish require feeding every two days in summer and once weekly in
winter. Buy suitable pellets from a pet supplier. Trout pellets are
generally too rich in protein for fish such as carp and goldfish, and can
cause pollution problems in the pond.
Health
The principal
causes of death of fish in an aquarium or pond are overstocking and polluted
water. As fish must live permanently in the area where they eat and excrete,
the tank must be cleaned regularly to remove this material which will foul
the water. Learn to recognise normal fish behaviour, and know what to do if
the fish begin to behave in an unusual way. For example, fish gasping on the
surface is a sure indication of a fouled tank or pond with little oxygen
left. Other signs of infections and diseases are change of colour, swollen
skin or eyes, a swollen belly, a rotting tail or white spots over the body
of the fish. Check with your veterinarian for advice.
Remedies for some common problems such as white spot, fin rot and fungus are
sold from aquarium shops. Prevention is obviously better than cure, but
where a fish becomes sick it is best to remove it to a small treatment tank
so that the other fish do not become infected. Seek advice about treatment
from the local Aquarium Society or veterinarian.
Remember that tobacco, dog flea treatments and garden and household sprays
such as insecticide can pollute the aquarium or pond and kill the fish. Read
the labels carefully, seek advice and cover the tank before spraying.

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