Maintaining a healthy and stable pond environment is the single most effective method of ensuring fish stay in top condition. This is best achieved by filtering the pond, introducing fish gradually, feeding wisely and not over stocking. Fishkeeping perfection must be so easy!
Alas, if we had complete control over the above factors, then true, we could prevent the vast majority of health problems (those that are linked directly to water quality). But even then, there are factors completely out of our control, such as a pump failing or a heron injuring a fish which can lead to fish health problems. In many instances if foreseen, disease can be prevented by dosing with one of the many appropriate treatments available. However, they are most commonly used to treat problems that have already manifested themselves.
Furthermore, ponds themselves can develop problems that may require a remedy through chemical control. At the top of the list, we find algae problems, both blanketweed and green water. There are non-chemical methods to control green water that are very effective (a UVc clarifier) but the resultant clear water encourages the rampant spread of blanketweed, prompting us to treat against it. Other potions that we can add for the benefit of the pond (and ultimately the fish) include treatments that make tapwater safe for fish, speed up the rate at which a new filter may mature and even remove ammonia from the water during an acute water quality problem.
How to Dose
The methods used to treat fish in a pond are quite unique compared to other pets as the pond water itself is treated rather than the fish. The chemical dose is determined by the volume of the pond rather than the numbers or the size of fish. Consequently, when using a treatment it is necessary to know the precise volume of the pond (not forgetting the filter) or there will be the danger of imprecise dosing.
Formal ponds are relatively straightforward to calculate, using length x width x depth in feet x 6.25, giving the volume in gallons. Multiply this by 4.55 to get the volume in litres. Problems can arise in more irregularly shaped ponds. If dosing a preformed pond then the manufacturer will state clearly the precise volume of each of their ponds. If the pond is home-designed, using a liner or concrete then the most accurate way of determining the volume is to fill the pond through a water meter and record the volume.
Pond medications are formulated to precise concentrations and are added by volume using a dosing device to treat specific pond volumes Eg 10ml treats 500 gallons. Most disease treatments are toxic chemicals (how else would they kill disease?) so there is a danger of over-stressing or even killing pond fish by getting the dosing wrong.
By under dosing, the fish are being subjected to the mildly irritating treatment but for no long-term benefit, where as by overdosing, concentrations of chemicals that come into contact with the fish may be toxic to the fish as well as the disease-causing organisms. The main consideration is to treat with the dose that is sufficiently concentrated to kill the disease but not the host, and following the manufacturer’s instructions, this should be straightforward.
Furthermore, some medications against parasites or bacteria will recommend a multi-dose course of treatment to ensure that the treatment is completely effective as some organisms are only susceptible to treatment at certain life stages.
One final precaution when using medications is to provide additional aeration. Medications are highly active compounds and will cause oxygen levels to drop through a number of direct and indirect interactions with the pond environment. This can be achieved by using a particularly vigorous fountain head or by adding an air pump and airstones to both the pond and filter during treatment. UVcs should also be turned off.
Types of pond treatment.
Pond treatments can be divided into 2 groups; Those that treat fish disease and those that improve water quality.
Fish medications can be used as both a preventative and cure for many diseases and ailments. There is a definite seasonal cycle for diseases and by fully appreciating when fish are at their greatest risk of disease, ponds can be treated to reduce the likelihood of fish health problems.
Winter. Winter is the quietist period in a pond as fish and disease organisms are at their least active with little need to dose.
Spring. The period between the long dormant months of winter and the lengthening spring days is probably the period when pond fish are most likely to suffer health problems. Physiologically, having not eaten for several months, pond fish will be at their weakest point and as water temperatures start to rise, pathogen populations will start to proliferate. This is the period that it would be wise to consider treating your pond speculatively, reducing the risk of disease. Dosing the pond with a broad spectrum antibacterial or antiparasite treatment will reduce pathogen numbers to levels which will not pose as great a threat to your weakened fish.
Summer. Warmer pond water will mean that fish are most active at this period, but so will their disease organisms. However, by feeding regularly and maintaining a good water quality, fish should be capable of defending themselves against disease. Be vigilant for any abrasions or tissue damage that may result from spawning activity and be prepared to treat the pond against secondary infections.
Autumn. Just as you will have prepared fish for their winter break by feeding them regularly through the summer, they can also be eased into the winter by treating the pond, as you would have done in the spring to reduce pond pathogens.
There is a wide range of broad spectrum treatments available to treat bacterial problems. Symptoms such as ragged fins and reddened areas of tissue are all signs of bacterial infection that are likely to respond to treatment. In extreme cases, such as open sores or ulcers, fish may respond to topical treatment where medication is applied directly onto open wounds.
The classic symptoms of fish showing obvious signs of irritation by flicking and scratching against objects are a fair indication of fish suffering from parasites. Both microscopic parasites (such as Costia, Trichodina and Chilodinella) and larger parasites (such as anchor worm and fish lice) can be treated by dosing a pond with a course of medication. Perhaps the most common parasitic disease is white spot, where fish appear to have been sprinkled liberally with granulated sugar. A course of antiparasitic pond medication will also treat this frequent offender.
Fungus is most common in spring and autumn, invading lesions and tissue that has been previously exposed. Seen as cottonwool-like growths, fungus too can be treated effectively with proprietary pond treatments.
Pond water treatments. These can help to address any problems with the pond environment.
Algae problems. A range of treatments are available to treat, control and kill algae and blanketweed. They are effective through a range of methods from starving algae of light or nutrients or being wholly toxic to algae. Barley straw is a ‘greener’ method of controlling algae problems, releasing mild algae inhibitors as it breaks down steadily in water.
Tap Water Conditioner.
An effective treatment to neutralise toxic chlorine and chloramine and lock up toxic heavy metals in tapwater, making it safe for fish. This is a must in completely new ponds and its use should always be considered during top-ups and water changes.
Filter Starters Enzyme Treatments.
A new generation of treatments have appeared over recent years that harness natural solutions to pond problems. It can take months for a filter to fully mature, so filter bacteria cultures are available to put bacterial life in a filter, speeding up the whole process.
Enzyme preparations are also available that will ‘consume’ sludge and other organic debris that may accumulate in a mature pond. Simply pour in the solution and let nature take over.
Preventing water quality and fish health problems is our first priority as pond keepers, however, should problems arise, for whatever reason, there is likely to be a treatment that will address the problem and work in conjunction with an improving water quality as you address the causative problems.