Pond TreatmentsPond treatments are big business – as a quick look on the shelves of most aquatic suppliers will make very clear – and although they are often seen as “fish-medicine” they also include types of preparation designed to eradicated pests or improve water quality.

Fish can be affected by a variety of illnesses and unfortunately one ill fish can often mean a pond-full will shortly follow so it is essential to make an accurate early diagnosis and follow up with the correct treatment. However, detected early, most of the commonly encountered diseases usually respond well to prompt treatment.

Fish Health

When using any pond treatment it is essential to read the instructions thoroughly and follow them carefully especially with regard to storage, dosage and handling, since many of the active ingredients in the remedies are also toxic to fish, wildlife, pets and people. For this reason too, it is essential to resist the temptation to add a little more to get the job done quicker – overdosing is counterproductive and can be seriously harmful, not least to fish and beneficial filter bacteria. Of all the chemical treatments in the aquatic medicine chest, the most well known are probably acriflavin, formaldehyde and malachite green.

  • Acriflavin, familiar as an antiseptic from human medicine, is used in a similar way to counter bacterial and fungal infections in fish and can also be valuable in controlling some kinds of parasites.
  • Formaldehyde is a very powerful disinfectant and can be used very effectively to treat a number of external parasites, particularly Gyrodactylus and Dactylogyrus.
  • Malachite Green is commonly used to treat fungus and external parasites. It is one of those chemicals which definitely need to be handled with respect, particularly in its powdered – and highly concentrated – form.
  • For parasite infections such as Costia, Chilodonella, Epistylis, Ichthyopthirius (white spot) or Trichodina, the best treatment is a combination of malachite green and formaldehyde – known as the Leteux-Meyer mixture after the two scientists who discovered it. Today, it is available as a ready-made commercial preparation – marketed as F.M.G Mixture – though it is not recommended for ponds stocked with Orfe, Rudd or Tench, as they seem particularly sensitive to its effect.
  • Methylene blue is one of a range of old traditional fish-keepers remedies for bacteria, fungi and parasites. Although it has become less popular with the development of other treatments – not least because it is also highly toxic to both plants and filter bacteria – it is still sometimes mentioned, especially in older books on pond-keeping. Dosage rates are often surprisingly small – often around 10ml per 1000 litres of pond water – though the exact dose will appear on the product labels – and should be carefully followed.

Other Treatments

Water quality is probably the single biggest factor in fish health and much of the illness and disease in the pond can be traced back to this. While medication can be very effective at treating affected fish, it does not address the underlying cause. With around 90 per cent of the blame for health problems laid at the door of poor husbandry, it is not surprising that some of the pond treatments on sale are aimed at improving water quality. Dechlorinators remove harmful chlorine from tap-water, for instance, while anti-foaming and sludge reducing treatments are also available. There are even specially formulated pond plant fertilizers designed to provide the missing nutrients required by pond plants, but avoiding boosting the nitrate and phosphate levels which could drive unwanted algal growth.

Treatments to help in the perennial struggle against algae are amongst the most commonly used – products such as Aquaclean or Bradshaw’s Get Rid of Green Water are very effective at controlling suspended algae and there are many products to deal with blanket weed also. Of these, barley straw – a natural and environmentally friendly additive – has been widely hailed as something of a “miracle cure”, though not all pond keepers agree. It is an organic, enzyme-based approach which naturally inhibits algal growth, though it can take a few months to have an effect and needs to be repeated several times over the year.

Algal weed killers – algicides – are also available, but they need to be selected with care if the pond has already been planted as they can harm other types of plants too. Other anti-algal treatments work by binding up and removing the nutrients from the water – denying them to the algae – the latest generation of these using a culture of beneficial bacteria, which are supplied either freeze-dried or “dormant” in a solution.

Pond treatments are an important part of the water-gardener’s armoury – both against disease and problems of water chemistry. Although no potion can ever replace good husbandry, used wisely, they can be invaluable aids to providing a healthy and harmonious environment within the pond.

Last Modified: January 25, 2022