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Hongtai Aquarium Water Conditioners

Hong Tai Aquarium Products PTE LTD


Effective treatment of diseases for all things on earth depends on accurate diagnosis of the diseases and the correct usage of the best drugs and chemicals available at that point of time.   Most drug failure in treating fish diseases is due to improper diagnosis.  Since fish don’t talk or complain, most diagnosis are based on external observations and their behaviours.  Very few hobbyists will send their fish for pathological tests before giving them any medical treatment.

In the aquarium trade there are many drugs and chemicals used in the treatment of aquarium fish diseases.  Unfortunately most of the scientifically proven treatments are based on work with food fish. There is much information that purports the efficacy of many drugs and chemical formulations for treating aquarium fish diseases, but most lack  reliable scientific data supporting their use.  Most of over-the–counter products are based on the so-called established formulations by the few aquarium fish experts.

Some products are poorly formulated with poor quality pharmaceuticals.  Instead of helping the aquarium enthusiasts to treat their sick fish, they destroy the fish.  This will indirectly discourage the fish hobbyists (especially the new enthusiasts) from pursuing their new interest.  The aquarium trade may also lose a large number of potential customers.

Most of the defects in the formulation of aquarium pharmaceuticals by some over-the- counter aquarium remedies manufacturers arise from the use of substandard raw materials – maybe intentionally to reduce cost. For example: a kilogram of Methylene blue technical grade (used in the tanning and paint manufacturing industries) cost only S$16.00 while one kilogram of Methylene blue B.P.C.(British Pharmaceutical Codex) for medicinal purposes cost about S$100.00!  Another chemical is the Formalin.  The commercial grade is cheaper by almost 30% as compared to the pharmaceutical grade

I have seen Methylene blue Technical Grade packed in 1 kg. plastic containers. The content was plainly labeled as Methylene Blue without stating the qualities or standards with an address of a German Chemical Company as manufacturer. It was being sold at a value meant for medicinal purposes.

If the use of aquarium pharmaceutical, or over-the-counter remedies is required, be sure to purchase them from reliable sources.  Always insist on U.S.P. or B.P. or B.P.C. or their Veterinary grades and qualities.  State clearly the type you required – water soluble or insoluble.  Don’t waste money on the wrong grade of drug.

Unfortunately, some aquarium shops will recommend items which will bring in the most profits for them. The best quality products are not recommended because they usually have a much lower profit margin.

The following drugs and chemicals are commonly used in the aquarium fish culture.  For general information, their dosage, qualities and standards are given as a guide.  Dosages as far as possible are given within a range, since accurate dosage depends on water and environmental conditions.

For in-water treatment, water quality can greatly affect efficacy and ichthyotoxicity.  Related pathogens can also vary in susceptibility.

If you are not sure of the dosage, always start with the lower dosage.  If the disease does not respond adequately, repeat the treatment with a higher dose.  Always look out for adverse reactions.  For oral medication, dosage varies with feed intake.  Make a higher concentration of drug in the feed if the fish eats less.   If the fish is unable to eat use a soluble drug for in-water treatment.

ACRIFLAVINE  B.P.C. – Also known as TYPAFLAVIN, NEUTROFLAVINE, GONOCRINE, OR PANFLAVINE.  A  group of quinoline antimicrobial dyes structurally related to acridine.  Hydrochloride salts are normally used because it is more stable in aqueous form.  Bacteriostatic against many Gram-positive bacteria but less effective against Gram-negative bacteria.  Not effective against spores.  Use for early stages of fungal, bacterial infections and infestations of the diseases.  Very effective for external wounds and cuts.  Use 0.01% as preventive and 0.03% for treatment.

MALACHITE GREEN is a diarymethane dye, which  is the most effective agent for treating water mold infections of fish and eggs.  Also effective against protozoan ectoparasites.  Toxic to some fishes such as fries or baby fish,  tetras, catfish, and loaches.  Be careful and watch out for adverse reactions when treating fish without scales. There are many grades of Malachite green in the market. Make sure you use only the Zinc Free oxalate grade.  Use 0.1 mg per litre for prolonged immersion and 100 mg per litre as swab to skin lesions.

METHYLENE BLUE – An effective agent for treating and preventing bacterial and fungal infections of freshwater fish eggs and for treating ectoparasites of fresh water fish.  Use 2 mg. per litre of water and repeat on alternate days for up to 3 times.  Use the pharmaceutical or B.P.C. grade.

METRONIDAZOLE (Flagyl) – An effective treatment for hexamitosis, spironuleosis and some bacterial infections since the 1970’s.  I normally use the injections (200 mg/ 25 ml. In vial form.) for prolonged immersion at the dose of 20 mg. per litre (i.e. 1 vial for use in 10 litres of water).  Add 1 vial every day for three day before stopping treatment.  It is more efficient to use as feed if the fish will consume food.  For feed use 100 mg. per kilo of body weight.

FORMALIN – An aqueous solution of 37% to 40% formaldehyde gases.  Formalin is volatile and irritating with a very pungent odour.  The commercial grade has darker colour and sometimes with brownish precipitates.  The  better B.P. grade is more stable and the liquid is practically colourless.  As a prolonged immersion in aquarium use, 0.015 ml to 0.025 ml per litre every other day, for three days.  For one-hour bath, use 0.125 ml to 0.250 ml per litre.


These wide range of pharmaceuticals are mainly used for the treatment of bacteria diseases of aquarium fish.  This group of drugs, also known as antibacterial agents, is highly abused in their uses, both therapeutically and prophylactically, by the aquarium industries.  All antibiotics when used therapeutically must be for at least 3 days even if the diseases seem to have disappeared or cured.  The prophylactic use of antibiotics should be discouraged as it is the main cause of a high prevalence of multiple antibiotic-resistant bacteria in aquarium fish.  It is not wise to start your fish on antibiotic therapy without knowing the causative agent (i.e. the type of bacteria ).   However, because it is difficult to pin point the causes of most bacterial diseases in aquarium fish without elaborate laboratory tests, most aquarists will just use any type of antibiotic available.  Fish treated with antibiotics should be monitored closely to ensure that the treatment is effective and complete.

Dosage of antibiotics depends largely on severity of diseases and tolerance of the particular species.  There is no fixed dosage and generally one capsule or tablet meant for human may be used in 1 litre to 5 litres depending on type of fish and severity of their problems  Generally, if the antibiotics are insoluble in water it is better to use in-feed method of administration while the soluble type are more appropriate for in-water treatment.

AMOXYCILLIN and its salt Trihydrate are insoluble in water.  Use 50 to 80 mg. per kilo of body weight as feed for 10 days.  Amoxycillin sodium are the soluble salt and more suitable for in water treatment.  Use 250 mg. to 1 to 5 litres of water.

AMPICILLIN and its salt Trihydrate are insoluble in water, use as feed.  Use the soluble Sodium salt for in-water treatment.  Both dosage are the same as Amoxycillin.

CHLORAMPHENICAL is the drug of choice  for abdominal dropsy and gold fish ulcer diseases caused by Aeromonas Salmonicida.  Very unstable in liquid form but the Chloramphenical Sodium Succinate at the dosage of 40 mg. per litre are poorly absorbed but stable in water for slightly more than 20 hours.  More suitable for use as  injection at the dosage level of 20 to 50 mg. per kilo of body weight once weekly for two weeks.  For Feed use 500 mg. per 100 gram of feed and feed twice daily for 3 days.

CHLOTETRACYCLINE, OXYTETRACYCLINE, and TETRACYCLINE are the most commonly used tetracycline groups of drugs   Use their water soluble  Hydrochloride salts for in-water treatment and make sure that your aquarium water is slightly acidic for best results.  It is better to use the pure powder than from the capsules  which are meant for human use.

Most capsules contain lactose, starch  or even sugar as inert ingredients but these are not suitable for aquarium use.  If water changes to brownish or reddish colour, replace at least 25 %; or better still change to a new tank to avoid adverse reactions.

Dosage for prolonged immersions: 20 to 100 mg. per litre of water for at least 3 days.   As feed, the Oxytetracycline (Terramycin) are preferred at the dosage of 50 to 80 mg. per kilo of body weight for 10 days.

ERYTHROMYCIN and its groups are mostly insoluble in water and as oral feed they have very bitter taste.  They are not suitable to use for prolonged immersion.  The Erythromycin Phosphate or Thiocyanate has been used as feed for food fish at the dose of 100 mg. per kilo of body weight for 10 days.

NEOMYCIN SULPHATE an aminoglycoside antibiotic used for topical administration to damaged skin, open wounds and also infected cavities.  Dosage for prolonged immersion is 50 mg. per litre of water every 3 days for 9 days.  Cross-sensitivity with other aminoglycoside may occur.



These Nitrofurans are an effective group of synthetic antimicrobials.  Some are stable in both fresh and salt water and are rapidly absorbed by fish.  They are effective against many of the common pathogens that affect fish.  A single bath treatment is often effective against susceptible organisms.  Suitable for use as feed and as prolonged bath.

Unfortunately, Nitrofurans are carcinogenic, genotoxic, and mutagenic and are strictly illegal for use in many countries, including United States and Japan.  But the Japanese are exporting the products packed in beautiful 5 gram silver-foiled packings to other Asian Counties like Singapore, Thailand and Malaysia.  The most unfortunate thing is that some aquarium shops introduce these products as a cure – for all fish problems with total disregard for the safety of the people using them.


OXOLINIC ACID –  A popular quinolone, a class of synthetic antimicrobials that are effective against many gram-negative bacterial pathogens of fish.  They are well absorbed orally and can be bacteriostatic or bactericidal.  Oral formulations: 10 mg. per kilo of body weight for 10 days.  For prolonged immersion use 1 mg. per litre for 24 hours.

FLUMEQUINE –  structurally related to Oxolinic Acid and Nalidixic acid and are used for the same purposes.  Dosage:  As feed, use 10 mg. to 1 kilo of body weight for 10 days.  For immersion use 5 to 10 mg. per litre.  Maintain pH between 6.5  to 7.5.   Use higher dosage for marine water.

NALIDIXIC ACID – another  quinolones – more suitable to use as a bath at the dosage of 10 to 15 mg. per litre for 1 to 4 hours.

SARAFLOXACIN – claimed to be the latest addition to the fluoroquinolone family.  Has broad-spectrum potency against many fish pathogens and are being investigated by several commercial fish hatcheries.


SULFAMETHOXAZOL – TRIMETHROPIM (Bactrium) – The most popular Sulpha drug used in the aquarium trade.  Used mainly as feed at the rate of 10 mg. per kilo of body weight for 10 days.  Most drugs in this class are toxic to fish while some are virtually useless because of widespread resistance.


These are series of non-pathogenic, dorman or sporulated (not freeze dried) bacteria specially designed to overcome a variety of aquaria waste problems.  A specially designed synergistic combination of bacteria such as Bacillus Subtilis, B. Licheniformis, B. Polymyxa, Pseudomonas Aeruginosa, P. Putida, P. Fluorescens, and Escherichia Hermannii are used to degrade organic matter.  The other two species of popular nitrifying bacteria  (Nitrosomonas, Nitrobacter) are used for ammonia removal.  They are effective only if used correctly.  Their shelf-life is about 6 months if properly stored.

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