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Introduction

Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the harvesting of wild fish. Mariculture refers to aquaculture practised in marine environments.

Particular kinds of aquaculture include fish farming, shrimp farming, sandworm farming, oyster farming, algaculture (such as seaweed farming), and the cultivation of ornamental fish. Particular methods include aquaponics, which integrates fish farming and plant farming.

History

Workers harvest catfish from the Delta Pride Catfish farms in Mississippi

Aquaculture was operating in China circa 2500 BC. When the waters subsided after river floods, some fishes, mainly carp, were trapped in lakes. Early aquaculturists fed their brood using nymphs and silkworm feces, and ate them. A fortunate genetic mutation of carp led to the emergence of goldfish during the Tang Dynasty.

Japanese cultivated seaweed by providing bamboo poles and, later, nets and oyster shells to serve as anchoring surfaces for spores.

Romans bred fish in ponds

In central Europe, early Christian monasteries adopted Roman aquacultural practices. Aquaculture spread in Europe during the Middle Ages, since away from the seacoasts and the big rivers, fish were scarce/expensive. Improvements in transportation during the 19th century made fish easily available and inexpensive, even in inland areas, making aquaculture less popular.

Part 1

Designing, Constructing and Stocking a Fish Pond

There are many smaller and very good set ups that have been built, and it is important to see as many ponds as you can before you decide on a design. This is a big advantage in belonging to a local club because then you can visit other members, and often a club has books in the library which shows photographs of various ponds. There are now quite a few photos of ponds appearing on home pages on the Internet. Let us now start looking at some of the things to consider before designing your pond. The position of the pond and the size and shape will inevitably depend on one another so you can not really decide on one without the other. The order in which they are decided are not necessarily in the order shown below.

Pond Design and Construction

1-Soils should be tested to determine if they are capable of holding water. Soils with clay, clay and loam, or sandy loam are best. Soils with limestone, shale or sand and gravel should be avoided because they will allow seepage.

2- The dam should be constructed with a well-built spillway to allow control of flood waters. It is desirable to install an overflow structure with a bottom drain in the pond. The ability to drain a pond provides options sometimes necessary to properly manage water and fish in a small pond.

3-As a general rule, the deeper the better. The pond should be no less than one acre with at least 24% of the surface area being more than 15 feet deep. This will help keep water levels stable and minimize winter-kill and evaporation during the summer. Ponds with a constant flow-through generally provide better conditions for fish survival.

4-There should be grassy or wooded barrier strips between the pond and cultivated areas to reduce pond siltation and possible pollution from runoff. Steeper slopes demand greater buffer strips.

5-Water quality is important to fish production and survival and includes many factors. Consider having your water tested to make sure it is compatible with your goals and objectives. Some factors to consider include: pH level, alkalinity, amount of dissolved gases such as oxygen, heavy metal concentration, acidity, total dissolved solids, nutrient levels and turbidity.

6- If the primary source of water is from a well, water should be aerated to assure adequate dissolved oxygen content and dispersal of other gases. This can be accomplished by discharging the water over a short run of rocky substrate that creates turbulence before entering the pond. However be mindful of potential soil erosion in the area from the well to the pond.

7-Fences should be erected to exclude livestock. Livestock tend to congregate around ponds, trampling the edges, causing the banks to erode and muddy the water, degrading water quality and limiting the diversity and health of vegetation around the impoundment.

8-Transplanting live fish from other water to your pond without a permit is illegal. This practice can also severely damage your pond by introducing diseases and unwanted fish species that may prevent the creation of a desirable sport fishery.

Position of pond.

1-The first idea is to place the pond near to the house so that you can see the fish even when it is a cold and windy day.

2-You should keep the pond away from large trees as the roots especially in the case of species such as Weeping Willows will seek out water and can damage the pond especially in the case of pond liners.

3-Privet hedges are often suggested to keep the wind off the water surface of the pond, but on a windy day in the Autumn a lot of leaves will fall into the pond.

If possible the pond should be in a sunny open position, but again this is not always possible.

1. Paddy ponds are embankment ponds built over flat ground. They have four dikes of approximately equal height. The size of the dikes, and thus the volume of earthwork, is usually limited to the minimum because of the need to import the soil material or to find it near the site.

Safety.

It must be remembered that with a six foot deep pond below ground then with the foundation and base the initial hole will be eight feet deep and especially if there is heavy rain then there is a danger of the sides collapsing and even undermining the foundations of the house itself.

Never plant large trees on or near dikes

Crops may be planted on top of dikes

1. If the weather is dry, you should plan for regular watering of the newly planted grass. Use mulching to reduce soil evaporation.

2. When it rains heavily, use temporary protection, such as hay or other suitable materials, to avoid severe erosion of the dikes until a grass cover is formed.

3. Never plant large trees on or near dikes because their roots would weaken the dikes. In some areas, vegetable crops and forage bushes can be grown, but care should be taken to select plants with a good ground cover and with roots that do not weaken the dike by penetrating too deeply or disturbing the soil.

4. Care should be taken to keep the dikes in good condition, and only small animals should be allowed to graze or browse on them.

Selecting the grass cover

The best protection is obtained from perennial grasses (Gramineae) with the following characteristics:

fast spread into a dense cover, through creeping, rooting stems (stolons) or underground rhizomes;
well adapted to local climate, particularly if seasonally dry;
easy to propagate vegetatively, for example by transplanting stolons or rhizomes.

Type & Shape.

The first thing to decide is if you want a formal or informal pond. Again this where your research into all the various other ponds and photographs will help you to come to a decision.

In the end it is a compromise and each pond should be built to suit your personal tastes.
Some prefer to have their pond level with the ground as this fits better into the landscape of the garden whilst others prefer to have it raised up by a couple of feet as it is easier to see the fish whilst sitting on the wall.
The pond can be any shape, but for ease of building and especially when using a butyl liner sharp curves should be avoided as much as possible.

Size of pond.

Everybody likes to make their pond as large as possible, but there are several things to take into account.
The larger the pond then the more maintenance and personal effort will be required to keep that pond in top condition for your fish.

Then we have the cost, not only the initial cost of building the pond and the larger filter system required, but of running costs. Items where cost depends on the gallon age of the pond are : -

Electricity for larger pumps.
Cost of replacement pumps.
Chemicals including salt for Spring & Autumn treatments, or any other treatments you need to carry out.

Depth of pond.

the pond should be six feet deep, and if you are building a large pond say 18ft x 12ft this is probably correct and looks right when completed. If, however you are building a much smaller pond then this depth does look completely out of proportion. In these cases it may be much better to have a pond say with a minimum depth of say 4ft 6ins with a depth of 5ft in way of the bottom drains.

Pipe inlet

Stand-pipe outlet

Earthen canal inlet

Monk outlet

Draining from excavation trenches in a paddy pond

Habitat Considerations

1- Ponds and reservoirs should be constructed with an irregular shoreline. This helps reduce wind and water erosion along the banks, which will prolong the life of the impoundment. Irregular shorelines and varying depths also provide a diversity of habitat conditions for various life stages of fish and aquatic organisms.

2- Consider adding boulders or clusters of natural woody debris, such as tree trunks anchored into the deepest portion of your pond before filling. These features can provide cover for various life stages of fish and increase the habitat for a natural food base, such as insects. Keep any underwater structure well below the surface water elevation to avoid accidents with any surface

3- Extensive shallow areas (less then three feet) should be avoided when constructing your pond because they encourage growth of aquatic vegetation, cause oxygen depletion during winter, and may emit unpleasant odors.

4- Some aquatic vegetation in pond is good for fish cover and forage production. Too much can contribute to fish mortality and make your pond unsightly. Minimize excessive vegetation growth by limiting the contribution of nutrients that enter your pond from adjacent areas of livestock use and fertilized fields. Supplemental feeding of fish and waterfowl should be avoided due to the added nutrients that can be introduced into the water.

Part 2 Fish Pond Water Quality

Water quality is one of the most overlooked aspects of pond management - until it affects fish production. Clay turbidity in ponds is one of the most common quality issues we address. However, several other variables influence water quality for fish including water temperature, phytoplankton, photosynthesis and pH, carbon dioxide, alkalinity and hardness. Additionally, water quality can be affected through the interaction of these factors.

This is a composite of a series of articles dealing with the chemical makeup of pond water. How to measure what is in it, what is good, what is bad, and what to do about it.

By introducing fish into your pond, you have assumed the responsibility for the care of these creatures. This includes not only feeding them but also providing them with a healthy environment in which they can live and thrive.

Partial determination of the quality of this liquid environment can be made through chemical measurements. An established pond with the fish appearing healthy should be checked every month or so. It is only when something out of the ordinary is observed and possibly during seasonal changes when an additional test or two might be needed.

A simple test at the right time may prevent a small problem from becoming a catastrophe. When starting up a new pond or bio-converter system, daily tests may be required until the converter comes on line, then weekly for a couple of months until the system has stabilized.

Do not confuse the terms water quality and water clarity.

1-Crystal clear water can contain compounds that are deadly to your fish.

2-Green water, caused by excessive phytoplankton growth can actually be beneficial to the fish although not very beneficial to the pond keeper who can't see them.

3-Water clarity can give some indications as to mechanical filtration effectiveness.

Biological Filtration / The Nitrifying Cycle

The Nitrifying Cycle:
A biological filter is a filter that houses and encourages the colonization of good, nitrifying bacteria. The nitrifying cycle must be active for a pond to be healthy. Fish and dying plants give off waste. This waste must be converted to fertilizer or it will kill the fish in the pond. It is the job of the nitrifying cycle to do the conversion.

Pond Nitrogen Cycle

Each component of this system requires the other components to survive and prosper. The basic portion of the cycle is shown above.

1-Fish waste and other organic waste is converted by bacteria and fungi to Ammonia compounds. These compounds can be injurious to the fish, but a healthy biologic converter populated with Nitrosomonas bacteria consume these Ammonia compounds and convert them to Nitrites. Unfortunately, the Nitrites are just as toxic to the fish as the Ammonia.

2-Again, the biologic converter comes into play with a population of Nitrobacter bacteria that convert the Nitrites to Nitrates.

3-The Nitrates are basically inert to the fish but usable by plants and algae within the pond.

4-The Nitrosomonas and Nitrobacter bacteria are called aerobic since they require Oxygen to convert their "food" to energy just like the fish.

Ammonia

The waste from fish and dying plant material is called Ammonia. Ammonia burns the gills of the fish and they will die. No reading of Ammonia is acceptable.

Nitrosomonas is the bacteria responsible for changing Ammonia to Nitrites and that is the first leg of the nitrifying cycle. If any reading of Ammonia is present you know that there's not enough Nitrosomonas growing in the filter.

NH3 Nitrosomonas ——> NO2

Ammonia, NH3, measured in parts per million (ppm), is the first measurement to determine the "health" of the biologic converter.

Ammonia should not be detectable in a pond with a "healthy" bio-converter. The ideal and normal measurement of Ammonia is zero.

When ammonia is dissolved in water, it is partially ionized depending upon the pH and temperature.

The ionized ammonia is called Ammonium and is not toxic to the fish.

NH3 ——> NH4

As the pH drops and the temperature decreases, the ionization and Ammonium increases which decreases the toxicity.

As a general guideline for a water temperature of 70°F., most Koi would be expected to tolerate an Ammonia level of 1 ppm if the pH was 7.0, or even as high as 10.0 if the pH was 6.0. At a pH of 8.0, just 0.1 ppm could be dangerous.

Test kits are available in two basic types. Both read the total of Ammonia and Ammonium, so without knowing the temperature and pH, the toxicity cannot be determined. Suffice it to say that the only good Ammonia reading is zero.

The Nessler method type test normally uses drops with a colormetric chart. The Nessler test detects both free Ammonia/Ammonium and also that chemically bound with anti-Ammonia chemical treatments (more about these later).

The Salicylate type test is a dual step, using liquid, pill or powder also with an associated color chart. It takes longer to perform and measures only the free Ammonia/Ammonium. Since only the free Ammonia is harmful to the fish, the Nessler test can be misleading under certain conditions but provides additional information under others.

The recommended test kit should be able to detect 0-1 ppm of Ammonia particularly for ponds with normal pH levels above 7.0. A wider range kit, 0 - 5 ppm, would also be useful, particularly for those ponds with a typical pH of under 7.0. An Ammonia test kit is considered to be a requirement for all pond keepers.

Effects:
Ammonia tends to block oxygen transfer from the gills to the blood and can cause both immediate and long term gill damage. The mucous producing membranes can be destroyed, reducing both the external slime coat and damaging the internal intestinal surfaces. Fish suffering from Ammonia posioning usually appear sluggish, often at the surface as if gasping for air.

Source:
Ammonia is a gas primarily released from the fish gills as a metabolic waste from protein breakdown, with some lesser secondary sources such as bacterial action on solid wastes and urea.

Control:

1-Ammonia is removed by bacterial action in the bio-converter and some is directly assimilated by the algae in the pond.

2-Nitrosonomas bacteria consume the Ammonia and produce Nitrites as a waste product. A significant portion of this bacterial action can occur on the walls of the pond as well as in the bio-converter.

3-Ammonia readings may increase with a sudden increase in bio-converter load until the bacterial colony grows to accept the added material. This can happen following the addition of a large number of new fish to a pond or during the spring as the water temperature increases.

4-Fish activity can often increase faster following a temperature increase than the bacterial action does.

5-A bio-converter that becomes partially obstructed with waste and/or develops channels through the media may operate at a reduced effectiveness that can also cause the Ammonia levels to increase.

Treatment:
Chemical treatments to counteract Ammonia toxicity are available commercially under various trade names. These treatments, most of which are based on Formaldehyde, form a chemical bond with the Ammonia that prevents it from being harmful to the fish.

They do not remove it from the pond. The bio converter does the actual removal. Although most of these products use a dosage of 50 ml per 100 gallons to chemically bind up to 1 ppm of Ammonia, be sure and check the manufacturer's directions before use.

Note that Nessler type test kits will still show chemically bound Ammonia to be present until the bio-converter bacteria actually consume it.

If a pond has a healthy bio-converter, there is not only no need to treat with Ammonia binding chemical agents, it is better not to use them at all.

When Ammonia is detected (assuming a pH of about 7.5):

Increase aeration to maximum. Add supplemental air if possible.
Stop feeding the fish if detected in an established pond, reduce amount fed by half if starting up a new bio-converter/pond.
Check an established pond bio-converter for probable clean out requirement.
For an ammonia level of 0.1 ppm, conduct a 10% water change out. For a level of 1.0 ppm, conduct a 25% change out. CAUTION: If the tap water has a higher pH than that of the pond, adding the replacement water may make the situation worse.
Chemically treat for twice the amount of Ammonia measured.
Consider transferring fish if the Ammonia level reaches 2.5 ppm.
If starting up a new bio-converter/pond, discontinue use of any UV Sterilizers, Ozone Generators, and Foam Fractionators (Protein Skimmers).
Retest in 12 to 24 hours.
Under Emergency conditions only, consider chemically lowering the pH one-half unit (but not below 6.0).

Nitrites

Nitrites, having been converted from Ammonia, are still very deadly and need to be converted to Nitrates (fertilizer) by a good bacteria called Nitrobacter.

NO2 Nitrobacter——> NO3

If a Nitrite test shows any amount of Nitrites it shows us that our biological filter is lacking enough Nitrobacter to do the job.

Regardless of which bacteria it is, if our biological filter is lacking either or both of the two, it sets up a dangerous situation for the fish. Steps must be taken immediately to keep the pond and its inhabitants healthy.

Immediately perform an 80% water change.
Stop feeding the fish until you've attained a week of negative test results.
Add BioSeed to encourage the growth of the two nitrifying bacteria.
Add adequate biological filtration.

Nitrite, NO2-N, measured in parts per million (ppm), is the second chemical measurement made to determine the "health" of the biologic converter. Nitrite should not be detectable in a pond with a properly functioning bio-converter. Thus the ideal and normal measurement of Nitrite is zero.

A low Nitrite reading combined with a significant Ammonia reading indicates the Ammonia- Nitrite biologic converter action is not established, while a low Ammonia reading with a detect able Nitrite

reading indicates that the Nitrite-Nitrate bacterial conversion activity is not yet working.

Test kits are available in pill, powder, or droplet forms with color charts. Recom mended test kit range 0 - 4 ppm. A Nitrite test kit is considered to be a requirement for all pond keepers.

Source:
Nitrite is produced by the autotrophic Nitrosomonas bacteria combining Oxygen and Ammonia in the bio-converter and to a lesser degree on the walls of the pond.

Just as with Ammonia, Nitrite readings may increase with a sudden increase in bio-converter load until the bacterial colony grows to accept the added material. This can happen following the addition of a large number of new fish to a pond or during the spring as the water temperature increases.

Fish activity can often increase faster following a temperature increase than the bacterial action does. A bio converter that becomes partially obstructed with waste and/or develops channels through the media may operate at a reduced effectiveness that can also cause the Nitrite levels to increase.

Effects:
Nitrite has been termed the invisible killer. The pond water may look great but Nitrite cannot be seen.

1-It can be deadly, particularly to the smaller fish, in concentrations as low as 0.25 ppm.

2- Nitrite damages the nervous system, liver, spleen, and kidneys of the fish.

3- Even lower concentrations over extended periods can cause long term damage. Short term, high intensity, "spikes" which often occur during bio-converter startup may go undetected yet cause problems to develop within the fish months later.

4-A common indication of a fish that has endured a Nitrite spike in the past is that the gill covers may be slightly rolled outward at the edges. They do not close flat against fish's body.

Control:

About the only control of Nitrite is through the maintenance of a "healthy" bio-converter. Within the media, Nitrobacter bacteria combine Oxygen with the Nitrite to convert it to the relatively benign Nitrate.

The Nitrobacter bacteria receive considerably less energy from this conversion process than do the Nitrosomonas bacteria in the Ammonia to Nitrite process. For this reason, they are not as hardy and tend to be the last to come and the first to go when a problem occurs within the bio-converter.

Water change outs can reduce the levels temporarily by the same amount as the percentage of water changed. The addition of salt helps reduce the toxic effects significantly but should only be used as a interim measure, not as an ongoing treatment.

Whenever 0.25 ppm of Nitrite or more is detected in a pond:

Increase aeration to maximum. For a Nitrite level of 1 ppm or greater, add supplemental air, if possible.
Stop feeding the fish if detected in an established pond, reduce amount being fed by half if starting up a new bio-converter/pond.
Discontinue use of any UV Sterilizers, Ozone Generators, and Foam Fractionators (Protein Skimmers).
For a Nitrite level less than 1 ppm, conduct a 10% water change out and add 1 pound of salt per hundred gallons of changed water.
For a level between 1 and 2 ppm, conduct a 25% water change out and add 2 pounds of salt per hundred gallons of changed water.
For a level greater than 2 ppm, conduct a 50% water change out and add 3 pounds of salt per hundred gallons of changed water.
Retest and repeat above in 24 hours.
For Nitrite levels of 4.0 or greater, consider transferring fish.

NITRATE

Nitrate, NO3-N, measured in ppm, is the third and last measurement used to determine the "health" of the bio-converter. Nitrate is produced by the autotrophic Nitrobacter bacteria combining Oxygen and Nitrite in the bio-converter and to a lesser degree on the walls of the pond.

A zero Nitrate reading, combined with a non-zero Nitrite reading, indicates the Nitrite-Nitrate bacterial converter action is not established. Test kits are available with dual droplet or pill form with color charts. The recommended test kit range 0 - 200 ppm. A Nitrate test kit is considered nice to have but not required for the average pond. In an established pond with part of the routine maintenance including 5% to 10% water change outs every two to four weeks, Nitrate levels will normally stabilize in the 50-100 ppm range. Concentrations from zero to 200 ppm are acceptable.

Where Ammonia and Nitrite were toxic to the fish, Nitrate is essentially harmless. There have been reports that high nitrate levels may weaken the colors in Koi but there have also been reports that high nitrate levels can enhance the colors.

Nitrate is the end result of the nitrification cycle and is very important to plants in their life cycle. This is why the plants in your garden can flourish from being watered with the waste water from your pond (assuming you haven't added too much salt).

Note the large difference in the ranges of the test kits being used to measure Nitrate (200 ppm) as opposed to those for Ammonia and Nitrite (1-4 ppm). Assuming our the bio-converter was converting the equivalent of 1 ppm of Ammonia to the equivalent of 1 ppm of Nitrite to the equivalent of 1 ppm of Nitrate per day, it would take 100 days or over three months, (longer with any water change outs), for the nitrate levels to build up to the 100 ppm level. The Nitrate concentration is controlled naturally through routine water change outs and to a lesser degree through plant/algae consumption.

Heavy metal

Heavy metal contamination or loading into receiving water bodies may cause physiological and neurological burdens upon aquatic organisms as well as the bioaccumulation of these metals in fish tissue. Predatory birds and mammals also accumulate these toxins through consumption of fish. Pertinent to this study, chromium, copper, lead, and nickel all have moderate to high environmental hazard and ecological risk rankings due to known toxicity and persistence.

Many of these monitored elements are heavy metals such as cadmium, copper, mercury,

decreased aquatic insect abundance below a Wisconsin pond, which was attributed to a combination of low food quality and direct chemical effects.

The toxicity of heavy metals will be affected by their bioavailability. Organisms uptake metals through the food they consume, through absorption onto gills and through the skin. Bioavailability in turn is affected by water hardness, PH, temperature and age of the organism

Temperature

Whether you measure your pond's temperature in degrees Centigrade or degrees Fahrenheit or both, a thermometer is considered a requirement for all ponds. A floating pool or spa thermometer is good. It is recommended that it be floated in the filter/converter system or tied to an easy access point at the edge of the pond. At a slightly higher cost, the electronic indoor/outdoor thermometers on the market (i.e. Radio Shack) provide a continuous digital readout. Just drop the end of the waterproof outdoor probe into the water. (

Temperature Ideal Range 65°F-75°F (20°C-25°C), Acceptable 35°F-85°F (2°C-30°C)

The temperature of the pond normally follows that of its surroundings although with a delay related to the size of the pond. Direct exposure of the pond to open sky can cause larger swings in temperature. Direct sunlight during the day can cause the temperature to rise higher and heat loss on clear nights can cause the temperature to drop lower than shaded ponds. A clear night sky can absorb a large amount of heat from a small pond and actually drive the pond temperature below air temperature.

Events generally happen faster at higher temperatures and in smaller ponds. Over normal temperature ranges, biologic activity doubles for each 10° rise in temperature. The toxicity of Ammonia increases as the temperature rises and the amount of Dissolved Oxygen that the water can hold decreases.

Although Koi have been known to survive for limited periods at 100°F and even higher, the mortality rate of fish conditioned to 75°F water increases rapidly above 85°F. Above 80°F, supplemental air may be required. Below 55°F (12°C), Koi stop producing antibodies and at about 45°F (7°C) enter a state similar to hibernation. Bio-converter bacteria reproduction ceases at about 40°F (5°C).

Feeding fish versus temperature.

Less than 50°F........Do Not Feed

50°F-60°F.............2-4 times weekly

60°F-85°F.............2-4 times daily

Above 85°F............Do Not Feed

In all cases, try to feed only what the fish will normally consume in 10 minutes. Remove any uneaten food within an hour.

Fish do not like changes in their environment of any kind including temperature. Any changes add stress to the fish and the larger and faster the changes, the greater the stress. This is considered by many to be the primary reason that fish do better in larger ponds.

Water temperature influences the

1-onset of fish spawn,

2-aquatic vegetation growth and

3- the biological demand for oxygen in ponds.

As water temperature increases, it holds less oxygen. Additionally, plants and animals use more oxygen due to increased respiration rates. These factors commonly result in less available oxygen for fish during the summer and fall months.

Thermal Discharge

Elevated temperatures may increase the quantity of blue-green algae, a group known to produce compounds that are toxic to fish and livestock,

Other temperature impacts to stream ecosystems may entail the modification of crucial life history phenologies in fish and shellfish resulting in unsuccessful reproduction, premature death, and alteration of community structure.

1-Cool water species:

• require cool, but not cold water for survival and growth. These species can survive in warmer water than the previously discussed coldwater species, but still must be in water that is in the 60's and 70's degree range Fahrenheit for growth.

• Some commonly sought after cool water species are Walleye Pike or Walleye for short, and Muskellunge or Musky for short.

• Cool water species require slightly less oxygen for survival and growth than the coldwater species.

• Minimal levels of dissolved oxygen for cool water species is 4 PPM and lethal levels are around 2 PPM.

2-Warmwater species:

• require warm water, and since warm water holds less dissolved oxygen, they require less oxygen to survive and grow.

• Warm water species grow best in water that is 80 degrees Fahrenheit or warmer, depending on the exact species.

• Some common warm water species are Large Mouth Bass, Catfish, Bluegill, and Tilapia.

• Minimal levels of dissolved oxygen for warmwater species is 2-3 PPM and lethal levels are around 0.5-1 PPM.

• Within each category, the oxygen consumption rates vary according to size and species.

• The below table shows some typical oxygen consumption rates of adults and juvenile fish in each category . The numbers are in pounds of oxygen per 100 pounds of fish per hour.

Temperature Problems

Water Stratification

Another temperature-related phenomenon is water stratification. This occurs in deeper ponds as increased ambient temperature causes a warm, less dense layer of water to stratify over a cool, dense layer of water. Most of the oxygen is produced in the warm surface layer of water and over time oxygen can be depleted in the cooler layer. These layers may not mix for a long period until a cold front or thunderstorm cools the surface layer allowing the two layers to mix. This is often referred to as "turn-over." The result is a sudden dilution of oxygen and a simultaneously increased demand for oxygen from decaying organic matter. This can cause severe fish kills.

• Temperature problems are caused from uneven warming or cooling of the pond. During the summer, the surface water is warmed and the colder, denser bottom water does not get warmed as much.

• This causes two distinct layers of water with a dividing line, called a Thermocline The problems associated are due to inadequate mixing of the water.

• Oxygen diffused into the water from the air is not mixed with the cooler bottom water.

• Therefore, you have a warm, oxygenated layer of water on top of a cool, low oxygen level layer at the bottom.

• When the surface cools in fall, it becomes denser than the bottom and the pond "turns over" call Turnover.

• This causes a mixing of all water and an overall decrease in dissolved oxygen levels.

• Turnover can lead to massive fish die off and major problems with the pond.

• Now that we understand some basics of dissolved oxygen, we can get back to the temperature problems in the pond.

• Temperature problems are a seasonal issue. As the sun exposure to the pond increases through spring and into summer, the water warms.

• As the summer progresses, the water at the surface continues to warm faster than the water below because not as much sunlight penetrates the lower portions of the water column.

• The area of the water column that receives sunlight is called the Euphotic Zone. The layer of warm water is known as an epilimnion.

• Also, warm water is less dense or lighter than cooler water, so warm water stays at the surface and colder water sinks to the bottom.

• As the summer continues, this temperature difference expands. The surface water is very warm and the water below much cooler.

• The cold water layer is known as the hypolimnion.

• As stated earlier, the cooler the water the more oxygen it can hold. However, if the cool water has no exposure to the air or oxygen, it cannot hold the oxygen, no matter how cold it is.

• Therefore, the cooler water near the bottom does not have a continuous oxygen supply, and over time can turn anoxic or have all of its oxygen used up.

Dissolved Oxygen

Although water molecules contain an oxygen atom, this oxygen is not what is needed by aquatic organisms living in our natural waters. A small amount of oxygen, up to about ten molecules of oxygen per million of water, is actually dissolved in water.

This dissolved oxygen is breathed by fish and zooplankton and is needed by them to survive.

Rapidly moving water, such as in a mountain stream or large river, tends to contain a lot of dissolved oxygen, while stagnant water contains little.

The process where bacteria in water helps organic matter, such as that which comes from a sewage-treatment plant, decay consumes oxygen.

Thus, excess organic material in pond can cause an oxygen-deficient situation to occur.

Aquatic life can have a hard time in stagnant water that has a lot of rotting, organic material in it, especially in summer, when dissolved-oxygen levels are at a seasonal low.

Is a measure of whether water is acidic or basic. Fish have an average blood pH of 7.4, so pond water with a pH close to this is optimum. An acceptable range would be 6.5 to 9.0. Fish can become stressed in water with a pH ranging from 4.0 to 6.5 and 9.0 to 11.0. Fish growth is limited in water pH less than 6.5, and reproduction ceases and fry can die at pH less than 5.0. Death is almost certain at a pH of less than 4.0 or greater than 11.0. Pond water pH fluctuates throughout the day due to photosynthesis and respiration by plants and vertebrates. Typically, pH is highest at dusk and lowest at dawn. This is because nighttime respiration increases carbon dioxide concentrations that interact with water producing carbonic acid and lowering pH. This can limit the ability of fish blood to carry oxygen.

The pH of a pond fluctuates. It's at its highest in the afternoon and lowest in the morning. When the pond water's pH reading is below 7.0 the water is too acidic and is harmful to both plants and fish. Simply raising the pH is only a temporary fix to the problem. It needs to be stable. To correct the problem raise the pH to a point between 7.2 and 7.8 then stabilize it.

Alkalinity

Is water's ability to resist changes in pH and is a measure of the total concentration of bases in pond water including carbonates, bicarbonates, hydroxides, phosphates and borates. These bases react with and neutralize acids, buffering changes in pH. Carbonates and bicarbonates are the most common and important components of alkalinity. A total alkalinity of at least 20 ppm is necessary for good pond productivity. Water with high alkalinity and similar hardness levels has a neutral or slightly basic pH and does not fluctuate widely.

Hardness

Is a measure of alkaline earth elements such as calcium and magnesium in pond water. Hard water has a higher concentration of alkaline earths. Calcium and magnesium are essential to fish for metabolic reactions such as bone and scale formation. Additionally, hardness and total alkalinity can affect pH through interaction with the carbon dioxide cycle.

This is just a brief overview of some of the variables that influence water quality. Interactions between these variables can become complex and would require much more explanation. The take home message is that there is much more than clay turbidity influencing water quality, and, consequently, fish health and productivity.

Phytoplankton

Are microscopic plants that produce most of the oxygen and are the base of primary productivity in a pond. Phytoplankton depend on sunlight for photosynthesis and produce oxygen during the process. Phytoplankton use oxygen at night through a process called respiration. Extended periods of cloudy weather can cause a phytoplankton die-off, using oxygen during decomposition.

If phytoplankton are too abundant in a pond, the amount of oxygen used during nighttime respiration can cause oxygen depletions for fish. Oxygen levels are usually lowest during the hour just before daylight. Ideal phytoplankton bloom in water should result in visibility between 12 and 30 inches. Anything less than 12 inches can compound the above mentioned problems and anything greater than 30 inches begins to lower pond productivity.

Algae control

What is algae?

Algae (sing. alga) are simple organisms that derive energy from the sun by carrying out photosynthesis. The higher land living plants are believed to have originated from algae and they are quite similar to each other. You will however find a series of distinct organs in higher plants that can not be found in algae. Algae can be unicellular as well as multicellular and some types form large and complex forms. The “seaweeds” that you can encounter in the ocean are for instance algae; not aquatic higher plants.

Algae are an important part of the ecosystems where they occur, but they can also become a nuisance for aquarists, pond keepers and swimming pool owners. In order to successfully combat algae it is important to understand what algae are and how they subsist. Just like a land living plant, algae need light, water, nutrients, carbon dioxide and oxygen. Oxygen is produced as a bi-product of photosynthesis and getting enough carbon dioxide and water is rarely a problem in aquariums, ponds and swimming pools. The main limiting factors are therefore light and nutrients. By controlling the amounts of light and nutrients, we can carry out successful algae control in ponds, aquariums and swimming pools.

Pond algae control

Many different methods can be used to combat pond algae and the bests results are normally achieved by combining several different methods.

1-As mentioned above, limiting the amount of light and nutrients will make the habitat less suitable for algae.

2- Introduce algae eating organisms to the pond and/or use some type of algaecide.

Disadvantage of algaecide.

Before you decide to use an algaecide for pond algae control, you should keep in mind that

a- algae mass-death can have a devastating effect on water quality and make the oxygen levels of the pond decrease sharply. This can in turn harm or even kill fishes and other aquatic organisms in the pond.

b-Algaecides are a short-term solution; unless you combine it with other actions you will never achieve a stable pond with suitable amounts of algae growth.

3-Limiting the amounts of nutrients that reaches the pool is usually easier than limiting the light.

Algea Eating Fish

Algae Eating Freshwater Fish

Algae can become a problem in both marine and freshwater aquariums. In this article, we will focus on a few algae eating fishes that can be kept in freshwater aquariums to help keep algae under control. The causes of algae in an aquarium can be widespread, e.g. too much light, too many plant nutrients, or certain deficiencies in water quality. Many enthusiasts have turned to freshwater algae eating fish to be a natural “cleaning crew” in helping keep algae from overtaking an otherwise beautiful tank.

There are several species of fish to choose from when shopping for a “cleaning crew”. Each species is known for eating a certain type or types of algae, but few are known for eating more than one type.

Siamese Algae Eaters (Crossocheilus siamensis)
Otherwise known as SAE’s, many consider these to be the best algae eaters of them all. They are commonly mistaken for Chinese algae eaters, and many pet stores label species of fish as SAE when in fact they are not. The SAE is diligent when it comes to eating red algae, which most algae eating fish will not touch. They are a peaceful fish, although when older may become aggressive towards their own kind. They are also known to eat hair and beard algae.

Siamese algae eater

Siamese algae eater- picture by Spyder

Common name: Siamese algae eater, Siamese flying fox, Flying fox, Siamese fox
Scientific name: Crossocheilus siamensis
Max size: 6 inches / 15 cm
pH: 6.5-7 (tolerates a much larger range span)
Temperature: 75-79˚F / 24-26˚C

The Siamese algae eater is also known as the Siamese flying fox, Flying fox and Siamese fox. It is common in aquarium stores and a very good algae eater. A very similar species, Garra taeniata aka Epalzeorhynchus sp, is sometimes sold as Siamese algae eater which have earned that species the common name False siamese algae eater. A majority the Siamese algae eaters that are (or at least used to be). Siamese algae eaters need to swim to float. If they stop they sink to the bottom.

Diagnose Pond Water Quality Problems

Use this handy page to find problems with your pond water's quality and clear them up. Most of the time there is a simple solution. Every pond should have good water quality and it's for certain koi and goldfish cannot live without it.

Symptom	What It Is
Green Water / Pea Soup	http://www.ponddoc.com/Topics/DiagnoseWater.htm#Al Currently 0/5 Stars. 1 2 3 4 5 0 تصويتات / 349 مشاهدة نشرت فى 6 فبراير 2013 بواسطة husseinelshafe احفظ عدد زيارات الموقع 17,705

Dr.Hussien Mohammed Elshafei

Pond Water Chemistry

History

Selecting the grass cover

Part 2

Fish Pond Water Quality

Algea Eating Fish

Algae Eating Freshwater Fish