Ponds need regular maintenance if they are to provide fish with a
healthy and safe environment.

Problems are most likely to arise in the first year, before the pond
isestablished, and are typically caused by overfeeding or overstocking.

Frequent monitoring and an awareness of seasonal changes will
help avoid the major pitfalls.

Spring checks As fish begin to stir out of their period of winter
dormancy, spent in the depths of the pond, they are very
susceptible to minor illnesses, such as bacterial infections, which
can rapidly overwhelm their weakened immune
systems.

Thorough inspection of individual fish will help identify and treat
illnesses in their earliest stages .

Once the water temperature increases, fish regain their appetites and become

A well-kept pond that has healthy planting and good water quality
is an attractive addition to any garden, and will provide a healthy habitat for pond fish.

Seasonal koi pond plant care

Plants around the pond may benefit from a layer of leaf mulch to protect them in winter.

Plants in the pond itself that are vulnerable to freezing weather
must be transferred indoors before the first frost.

Although the winter pond may look bare (below left), the plants can
be returned to the pond in spring and will grow quickly over the summer (below right).

better able to fight infections.This surge in appetite, and the
resulting increase in waste products, causes a rise in ammonia
levels in the water, so now is a good time to maintain and
service filtration equipment.

The beneficial bacteria in biological filters are inactive during cold
weather, and such filters may need to be reseeded with bacterial cultures.

Live and freeze-dried cultures are available from suppliers of pond
equipment.

The addition of zeolite, a chemical that absorbs ammonia directly
from the water, may also be beneficial until the filter is fully functioning again.

Pond fish begin to show spawning behavior in late spring,
when new plant growth provides surface cover for the fish
and for any eggs and resulting fry in the pond.

Check regularly in case any fish have become trapped in reeds or

Removing leaves in the fall is easier if netting is placed over
the surface of the pond.

other plants, or any females have been driven out of the pond by over-energetic males.

During the summer,the increased temperature of the water and
greater activity levels of the fish result in lower oxygen levels.

If not controlled, plant and algal growth also reduces oxygen levels
in the water.

To maintain oxygenation, fountains and other water features
should be left on overnight, or special aeration equipment should be installed.

Preparing for winter

Pond plants begin to die back in the fall, and excess foliage
should be removed.

Falling leaves should not be allowed to accumulate on the surface of
the pond, because they decompose in the water and can harm the fish.

Covering the surface of the pond with netting keeps leaves out of
the water, and allows them to be collected easily.

If there are delicate fish in the pond, or any young from a late
spawning, they should be caught and transferred to an aquarium
for the winter to ensure their survival.

When the water temperature falls below 43°F (6°C), the remaining
fish may enter an almost completely motionless state, and will
not require feeding until spring.

Below around 39°F (4°C),a warmer layer of water will develop in the deepest part of

Algal blooms—sudden flushes of algal growth—can be a problem in warm weather.

Removing any dying or dead leaves from plants around the pond
will help limit algal proliferation.

Blanketweed is a type of filamentous alga, which can trap fish.
It should be removed regularly using a stick.

Duckweed grows rapidly, and will entirely cover the surface of a pond.

It can easily be controlled by scooping it off the surface.

Regular Pond Maintenance Tasks

• Check to see if fish are showing signs of ill health or behaving strangely.
• Ensure that the filtration system, if present, is functioning correctly.
• Feed the fish, according to their appetite, several times during the
  day, except in the winter or in very hot weather
• Note the water level in the pond; sudden falls indicate a leak in the pond liner.
• Check the ammonia and nitrite levels, especially in a newly established pond.

Weekly

• During the growing season, remove faded flowers of marginals, unless seed is required.
• Top off the water level in the pond if the evaporation level is high,
  using water treated with a dechlorinating product
• Test the oxygen levels in the water, especially in hot weather.
• Check for any signs of plant pests, such as aphids, removing them
  from the vegetation where necessary.

Monthly 

• Check the nitrate level of the pond water. It should not rise above 50 mg/l.
• Remove blanketweed so that it cannot choke other plants and pond fish.
• Prevent any build-up of algae on bridges or decking, which could make them slippery.Remove it by scrubbing the surface of the wood with a clean brush.
• Watch for any signs of moss growing on the surface of paving or
  stepping stones close to and surrounding the pond.
• Rather than stocking the pond to the greatest capacity at the outset,
  add further fish gradually over the spring and summer months.

the pond, where pond fish spend the winter. If there is a submersible pump installed, position it more than 6 in
(15 cm) from the bottom of the pond, and switch off water
features, such as waterfalls or fountains—otherwise, these
will circulate and cool the water by mixing the colder surface
layers with the warm layer below.

In mild areas, a pond heater can help to prevent the surface
of the pond from freezing over in the winter.

It will stop the area around the heater from freezing, allowing
noxious gases produced by decomposing plant matter to escape
from under the ice.

If ice has formed on the surface of the pond, never try to smash it,
because the shock waves will traumatize the fish and may even prove fatal.

Instead, melt the ice slowly by carefully holding a hot saucepan on the surface of the pond.

During the spring, place a net over the surface of the pond
or stretch it across a framework to protect exhausted fish
from opportunistic predators.

Decoys are available to deter birds, but they are unlikely to stop raccoons or cats.

CLEANING OUT A POND

Over time, sediment accumulates in the pond, and plant growth
proliferates, inevitably reducing the area of water that is accessible
to the fish.

At intervals of a year or so, it is a good idea to unertake a major clearout.

The best time is in early spring, because the pond will have time to
reestablish itself in the warm summer months.

If any cases of serious illness have occurred within the pond, it may must disinfection.

Some preformed pond units can be lifted out of the ground to make this task easier.

• Before starting the clearout, catch the fish and move them to a location where they will be safe.
• Siphon or bail out the pond water, removing other aquatic life, such as snails or dragonfly larvae.
• Divide and repot water lilies and marginal plants.
• Remove the silt using a spade or scoop, and hose out the base of the pond. The used silt can be dumped on flowerbeds.
• Refill the pond, adding a suitable volume of water conditioner.
• Allow the water temperature to rise before returning the fish and plants to the pond.

Remove the fish before cleaning, watching closely for small fry;
transfer the fish to a safe container.

Re-introduce the fish only after any replanting is complete; allow
the fish to settle without further disturbance.

The surface of a pond can become choked with aquatic vegetation (top).

Clearingout the pond, by thinning or cutting back the plants and
removing dead matter, provides the fish with a larger swimming
space, and makes the area neater, safer, and more attractive (bottom).