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How to use Coptrol to Control Algae in Aquaculture

Free floating and filamentous algae are a constant problem

in aquatic environments. In the nutrient rich, oxygenated

waters found in aquaculture algal blooms compete with fish

and crustacea for oxygen and nutrients. Coptrol a new-generation

algaecide remains soluble and active at lower rates for longer

periods.It is environmentally friendly. It offers a new approach

in the prevention and control of algae in aquaculture.

Algae and Algal Blooms

There is no easy definition of an alga. Algae are generally microscopic organisms, are generally thought of as simple aquatic plants which do not have roots, stems or leaves and have primitive methods of reproduction.

Click here for further information on algae.

Use of Coptrol in aquatic environments is a more efficient and

effective means of controlling algae than environmentally damaging

copper sulphate(bluestone).

Coptrol eliminates the problem of copper precipitation in "hard" water.

Coptrol permits lower concentrations of copper to be used in algae control. Because Coptrol does not precipitate in hard water the application rates are less critical.

Coptrol achieves longer copper persistence in water at levels that are toxic to algae.

Coptrol is non-corrosive, non-irritant and easy to use.

Coptrol works in all kinds of water, salt or fresh, hard or soft, turbid

or clear.

Copper has been used in balancing pond and water

environments

since the inception of the aquaculture industry. However, the concentrations of copper are critical and the "copper demand" of water varies widely. It is essential that this demand be known, as copper will combine with carbonate ions in water (which give the water its "hardness") to form insoluble copper carbonate. Thus, the copper goes out of the system and more must be applied to achieve the correct balance. This is often a trial and error process, which is costly in terms of time and money.

Copper in its ionic forms, e.g copper sulphate, is potentially hazardous to fish and presents some risk even when great care is taken in treating algae‑infested waters, that contain fish. However, Coptrol (a chelated

copper compound) is highly specific to algae and has been shown to

present a minimum hazard to fish when used in accordance with the label.

When Coptrol is used, protection from copper toxicity is provided where

water hardness is more than 50 ppm(50 mg/litre expressed as calcium-

carbonate). Below a level of 50 ppm of hardness, copper in a toxic form

may be liberated thus harming fish and crustacea.Water hardness

may be tested by using a commercial hardness test kit, or having

a small sample (about 250 mL) tested in any NATA registered laboratory.

Water temperature is also important. Below 16°C spatiation may occur

where copper can separate from the chelating agent, potentially being

harmful to fish and crustacea.

Where fish are a valuable resource, it is important to test the water for hardness, and then to test Coptrol application on a few fish before applying Coptrol to the main fish biomass. If water hardness is below 50 ppm or temperature below 16°C Coptrol should not be used in the presence of valuable fish and crustacea.

Application to fish impondments: Decomposing algae that has

been treated with Coptrol may lead to oxygen depletion of the water.

Lack of oxygen may cause fish to suffocate.

Therefore, in bodies of water containing fish, it is best to kill algae

slowly. It is recommended to treat only one third of the area, then wait

10 days to allow the oxygen level to build up again. Then, resume

the treatment beginning from the shore and moving outwards in bands

to avoid trapping fish in treated areas.

Effects of copper on fish

A large number of studies have been conducted on the toxicity of

copper to fish, whether the copper is naturally occurring or

introduced.

Note ‑ the label cautions against the treatment of waters containing trout and other species where water hardness is lower than 50 ppm

Moore (1984) describes naturally occurring copper in the ionic form as potentially

more toxic to fish than any other heavy metal except mercury. However, he notes

that copper is much less toxic to fish in waters with a high complexing capacity,

such as salt water. He also quotes data to confirm that copper is significantly less

toxic to trout in hard waters.

Moore (1984), Stiff (1971) and Pagenkopf (1974) are in general agreement that

ionic copper (Cu) and ionised hydroxides (such as CuOH) are the forms of copper

most toxic to fish. Coptrol contains copper only in the chelated form, in contrast

to copper sulphate which presents copper only in the ionic form.

Stiff (1971) noted that "natural" complexing of copper ions with glycine and humic

substances caused some reduction in copper toxicity. Sprague in 1968 suggested

that the chelating agent NTA (nitrilo-triacetic acid) could be used as an

anti‑pollutant to protect fish from copper poisoning.

Boyd (1979) reported that chelated copper algaecides are often recommended for

application to softwater ponds to prevent copper poisoning in fish. He further noted

that "The toxicity of the chelated (copper) compound to fish is less than that

of an equal concentration of copper in copper sulphate, so that species

with a high susceptibility to copper are not harmed in waters of low alkalinity".

Moore (1984) reported, "In copper polluted fresh waters, maximum concentrations

in muscle tissue seldom exceeds 1 mg/kg wet weight. Because muscle residues

are generally low, copper does not pose a threat to most fisheries, even those

in polluted waters.

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Coptrol has been proven to be highly specific to algae and presents minimal

risk to fish providing label instructions are followed exactly. Copper in

any soluble form is potentially toxic to fish and crustacea. Extreme care

should always be exercised in ensuring directions are accurately followed

when treating algae infested waters containing fish.

When Coptrol is used, protection from copper toxicity is provided where

water hardness is more than 50 ppm. (50 mg/litre calcium carbonate).

If water hardness is below 50ppm, Coptrol use is not recommended.

Shrimp/prawn Farms

Coptrol will eliminate a broad range of algae and control the growth of resistant species.

Coptrol will aid in the cure and control of diseases commonly found in shrimp.These include bacterial and gill diseases, tail ulcers and protozoan infections.

Treat shoreline first to avoid trapping aquatic livestock in shallows.

It is best to treat only 1/3 of the area at a time to avoid oxygen depletion of the water caused by decaying vegetation

Shrimp, Eel & Fish Dosing Table

Eel Ponds
To improve water quality and reduce "off flavour" and lower bacterial/parasitic load.	Use 1.7-2.0 p.p.m. 1.7-2.0 cc (ml) for 1 tonne of water	Dilute the required amount with 10 times the required volume of water. Pour or spray the resultant mixture evenly over the pond. After 2-3 days when algae dies, remove by hand. Repeat every 1-2 weeks.
Fish Ponds
Refer to eel ponds		Do not treat trout with coptrol unless water hardness is more than 50 p.p.m.

Warning

Do not use Coptrol in the rare cases where total water hardness (measured in grams of calcium carbonate (CaCO₃) is less than 50 p.p.m. Do not treat water if water temp is below 16 degrees C.

Purpose	Dose of Coptrol	Comments
	For young shrimp	For young shrimp
To maintain water colour	Use 0.4-0.5 p.p.m equivalent to 0.4-0.5cc(ml) in 1 tonne (1000 litres) of water	If water colour is normal, continue dose after 5-7 days using low dose,frequent application method.
	For adult shrimp	For adult shrimp
To inhibit algal growth	Use 0.85-1.7 p.p.m concentration 0.85-1.7cc(ml) added to 1 tonne (1000 litres) of water.	One application every 1-2 weeks
	For young shrimp	For young shrimp
To induce moulting	Use 0.4-0.5 p.p.m equivalent to 0.4-0.5cc(ml) in 1 tonne (1000 litres) of water.	Continue after 5.7 days.
	For adult shrimp	For adult shrimp
To induce moulting	Use 0.85-1.7 p.p.m concentration 0.85-1.7cc(ml) added to 1 tonne (1000 litres) of water.	One application every 1-2 weeks.
To maintain water quality reduce off flavour Lower bacterial and parasitic loads.	Add 1.8cc(ml) per 1 tonne(1000 litres) of water.	Apply every 30 days as required.
Disease Prevention
Bacterial/Algal disease Including Black Gill and Red Gill disease. Tail Ulcers. Protozoa Infections. Mould Infections	Use.85-1.00 p.p.m. 1.every 1-2 weeks as a preventative measure. .85-1.00 cc (ml) in 1 tonne (1000 litre) of water.
Disease Treament
Bacterial/Algal disease Including Black Gill and Red Gill disease. Tail Ulcers. Protozoa Infections. Mould Infections	Use 1.7-2.00 p.p.m. 1.7-2.00 cc (ml) for 1 tonne (1000 litres) of water. After 2-3 days use 1-2 p.p.m. concentration again.	When disease is under control revert to prevention concentration of .85 p.p.m.
To eliminate heavy filamentous algal infestations such as cladophora, chlorella etc.	Use at a rate of 1.7-2.5 p.p.m. 1.7-2.5 cc (ml) for 1 tonne (1000 litres) of water	Treat 2 or 3 times. When algae starts to die and turns yellow remove by hand.

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