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Hongtai Aquarium Pharmaceutical Products

Hong Tai Aquarium Products PTE LTD


Preventive treatment is extremely important for fish heath.  Prevent the above ten environmental problems and you will find your aquarium fish facing very little health crisis.  If your fish fall sick they may be treated by three major  routes of drug administration – in-feed or in-water medications and  by injections.


To make in-feed medication for ornamental fish, mix flake food, pellets or minced prawns with the drugs (usually antibiotic drugs or drugs that are almost insoluble in water) and solidify in warm agar or gelatin which is allowed to cool off before using as medicated feeds.


For in-water treatment of aquarium fishes the chemicals or drugs are added to the water for use as a bath, flush, a dip or as a prolonged bath.

  • As a bath – a low concentration of drugs is added to the water and the fish are placed in the solution for 30 to 60 minutes
  • As a prolonged bath – the concentration of drugs is even lower so that it is suitable for prolonged immersion for several hours or even days.
  • As a flush – a higher concentration of drugs are added to the water which is then flushed through with fresh incoming water. This means the fish will be in contact with the drug for 15 to 20 minutes.
  • In a dip – a highly concentrated solution of the drug is prepared and fish are netted into the solution for 30 to 60 seconds and then replaced in their original tank.  The concentrated solution in a dip is also commonly used as a direct application for infections due to external injuries or lesions on the body.


For big fishes like Koi, “Big-sized” Goldfish, Arrowanas, cichlids, you may consider using injections.  I would suggest, as a lay hobbyist, you should leave this to the veterinary surgeons or the professionals.

For aquarium fish there are three main methods of injections: (1) Intraperitoneal or IP, (2) Intramuscular or IM,  and  (3) Dorsal sinus.  A small gauge needle such as the 25GA or less is required.

In Singapore, you need a poison license to buy controlled drugs and one to store them.  Most injections are antibiotics or sulpha drugs and they are mostly classified as scheduled poisons (under the Poisons Act) in Singapore.  These regulations make injecting sick fish a real professional matter!

General identification of common fish diseases

As aquarium fish hobbyists we will only identify fish diseases by their visual signs in colour or growth (if any) on the diseased fish body and fins.  The behaviour of the diseased fish will also be taken  into consideration.

We leave the definitive identification procedures of diseases by using  the microscope and waiting for the bacteria cell growth to appear on culture media to the experts. After all, not all fish hobbyists own high power microscope or facilities to prepare culture media. To simplify the procedures in diagnosis and treatment of diseases, we separate them into the following groups:

( A ) Diseases caused by bacterial infections

Bacteria occur everywhere and come in various forms.  They can be shaped like sphere, rod, or spiral and arranged singly in clusters or chains. They are very numerous and most are useful to humans and fishes.

They are responsible for the decay of dead plants and animals, a continuous process which releases nutrients to be recycled repeatedly.  In the aquatic environment, the result  of  bacterial activities are responsible for the nitrification process, whereby the ammonia and nitrites are converted to the less harmful nitrates in the biological systems.   Bacteria are always present in aquarium water but those which causes outbreaks of fish diseases occur only when the fishes are kept in unsuitable conditions such as deteriorated water quality.  Bacteria that cause diseases or problems in aquarium water are known as “pathogenic” bacteria.  Many pathogenic bacteria live with our fishes and us.  We will never totally get rid of them in our aquariums or ponds; we can only control and contain them.

The main bacterial diseases in Aquarium fishes are:

FURUNCULOSIS – a very infectious diseases caused by Aeromonas Salmonicida. Affects mainly trout, salmons and ulcer diseases of Koi and goldfishes.  There are rod-shaped short gram-negative bacteria measuring about 2 microns.  The pathogens are transmitted through infected fish, skin parasites. Poor water quality foster a wider spread of the diseases.

DIAGNOSIS:  External signs are swollen abdomen, redness at the base of fins, in the mouth, in the grooves under the lower jaw, gill cover and around the anus and sometime the body wall are covered with boils and lesions as big as long as 20 mm.  These lesions will develop into ulcers in some species, such as carps and Kois.

In Kois, the ulcers will further develop into Carp Erythrodermatitis, a skin disease which will quickly lead to secondary fungal infections or invade the body leading to internal lesions and septicemia.

The affected fish usually looks lethargic,  darker in colour.  It loses appetite, stays at side of aquarium or pond and remains near the surface and is occasionally swept to downstream where there is less water disturbance. Internal organs and body tissues are also inflamed.


There is no low cost effective treatment for this disease.  If the fishes are cheap, destroy the whole lot, disinfect all the utensils, equipment, tanks and ponds with calcium hydroxide for one week before restarting your new stock.  If you have expensive fish such as Koi or some rare species, then you will have to try to save them.

The cheapest drug to use are the sulpha drugs such as combination of sulphamerazine (0.20g/kg of fish per day for 7 days) and  sulphaguanidine (0.10g/kg of fish per day for  seven days) powders incorporated into feeds for controlled feeding of sick fishes.  Oxytetracyclines ( 55 mg. per kg. of fish per day for 10 days) and Furazolidone (35 mg per kg. weight of fish per day for 20 days or more) are most commonly used in feed to treat affected fish except that the latter is known to be carcinogenic and banned for use in food fish farms.

Potentiated sulfonamides such as Tribressen (1mg/kg of fish per day for two weeks) are effective against Furunculosis therapeutically, but the cost is very high.  Oxolinic Acid (5mg/kg of fish per day for 10 days), Furazolidone (35mg./kg of fish per day for 14 days), Nitrofurazone (75 mg/kg of fish per day for 14 days ) and Oxytetracycline (55 mg/kg of fish per day for 10 days) have been prescribed frequently as additive to feed affected fish in their medicinal diet with good results.

Some Koi  breeders claimed to use Powders of Azactam  Gentamycin,  Kanamycin, and  Augmentin with great results! – but I believe that their wallets become very much lighter even before they can see any real result.  Alternatively, all fishes with external lesions or visible injuries must be dipped in undiluted RID-ALL ANTI FUNGUS for at least 5 minutes before placing them in the bath of the same medication of 5 ml. to 10 litres for big fish or 25 litres for small fish for about 3 days, then add in more medication for another week until the ulcer area begins to turn white.

If your fishes are mainly goldfish or Koi, then bath in RID-ALL KOI AND GOLDFISH SPECIAL instead.

COLUMNARIS INFECTION  (Tail and Finrot, Peduncle Diseases, Saddleback, “Cotton Wool” Diseases, Black Patch Necrosis, Haemorrhagic and Ulcer Disease) mainly caused by Flexibacter columnaris and various types of bacteria such as Aeromonas, Pseudomonas, and Cytophaga (myxobacteria).

Water with too high pH value and high temperatures, oxygen depletion, water contaminated  with faecal matter,  poor water quality poorly maintained aquariums or ponds and acute stress can encourage the disease.


COLUMNARIS is primarily an epithelial disease.  It causes erosive and necrotic skin and gill lesions that may become systemic.  It often appears as whitish plaques (or thick mucus) with red periphery on the head, percula and fins especially around the caudal fin.

Fragments of the fin rays may remain after the epithelium has sloughed leaving a ragged appearance (fin rot).

Lesions rapidly progress to ulcers usually within 24 hours, which may be yellow or orange due to masses of pigmented bacteria.   Lesions may also form black patches on body, fin and back (black patch necrosis).

The body, in severe cases may become bloated or swollen in some areas.  Ulceration spread by radial expansion may penetrate into deeper tissues producing a bacteremia (haemorrhagic septicemia and ulcer) and with external fungus growth (cotton wool diseases).

Columnaris gill infection are less common but with high mortality because of impaired gill filaments and tissues due to infections.

Peduncle Diseases are caused by several species of Cytophoga psychrophilus formally known as myxobacteria..  If the bacteria invaded the fins causing necrosis of  tissue and confine to the fins alone is called fin rot disease, but when the necrosis enters tissue at the base of the caudal fin or peduncle it is called the peduncle diseases.

The treatment  regime for the above group of bacteria diseases are the same.


Antibiotics such as Oxytetracycline hydrochloride  (100 mg per litre as prolonged bath daily for 3 days), and Neomycin sulphate (250mg. per 100 g feed every four hour for three days) or use 50mg/litre of water as long bath for at least three days), are effective treatment.

For prolonged immersion, use nifurpirinol 0.1mg. per litre and treat for 4 or 5 days.  Alternatively non-antibiotics treatments are also as effective.

Dilute RID-ALL COPPER AID from 5 ml. to 15 liters.  Dipped the affected fish in the final solution for about 5 to 10 minutes, before transferring them to another tank for a long bath with a normal dose of RID-ALL ANTI FUNGUS for at least three days.


EGG FUNGUS AND FISH FUNGUS – Fish and Egg fungi are caused by various species of aquatic fungi such as Saprolegnia and Acharya.  There are thousands of fungi in the aquatic world and most are saprophytes, feeding on dead organic matter. Some are parasites of animals and plants and some are an important source of antibiotics such as Penicillin.  Popular types of fungi are yeast and mushrooms.  Another type of fungal disease affecting gill tissue is known as Branchiomycosis.  It attacks mainly guppies.

DIAGNOSIS: A Cotton Wool-like growth or tufts on damaged skins and fins of fishes.   Generally, the fish might have already suffered from other forms of infections (ich, ulcers, etc.) which caused the mucus layer to become damaged.

The fungus will then attack the damaged area forming the well-known thin white threads known as the fungal mat or mycelium.  Large amounts of fungus and fungal spores are always abundant where there is plenty of decaying organic matter.  As a result,  the moment there is a dead fish egg available,  the spores will settle on the dead egg and the fungi grow rapidly to spread to the adjacent healthy eggs killing the whole lot.

Some fungi developing on or in gill tissue penetrate blood vessels which cause the gill to appear bright red from impaired circulation.  These groups of Branchiomycosis fungi produce spores that attach to the gill, germinate and produce hyphae that penetrate the gills epithelium.  The infected fish may be weak and lethargic with respiratory distress and sudden deaths are common.  The dead fish usually has bright red gills and if the pH of the water is acidic the mortality rate could reach 50%.


Fungi are very infectious but fortunately, they attack only damaged areas or lesions caused by other diseases.  They are usually secondary infections caused by insufficient care given to a series of serious bacterial infections or physical damage.  The natural layer of undamaged mucus that covers the healthy fish is the best protection against fungus attacks.  There are many effective remedies available for the treatment of fungus infection.  Most antibiotics (use the same dosage as in bacterial infections) can be used against fungus but not as effective as against bacteria.

Rid-All Anti-fungus at a dose of 5 ml. to 25 liters kills most fungi in the aquarium environment.  For better and quicker results remove the white threads or white mat with a twister and apply the damaged area with undiluted Anti-fungus before the general treatment.

(C) Parasites

There are thousands of various types of parasites infecting aquarium fishes.  Protozoan ectoparasites are the most common parasites encountered in the aquarium and cultured fish.  This group is a diverse array of mainly ciliates and flagellates that feed on the most superficial skin layer, known as the epithelium.

Most feed only on the epithelium’s surface, while some, (e.g. Ich)   penetrate into the epithelium.  The feeding activities cause serious visual damage to the hosts.  One of the most common damages caused by the parasites is reactive hyperplasia of the epithelium and an increase in mucus production.

When the hyperplasia is severe, it appears as a white cyst or peppered with white dots and cloudiness to the skin. The same problems can occur on the gills and lead to hypoxia (insufficient oxygen intake).

All protozoan ectoparasites have a direct life cycle and reproduce faster at a higher temperature.  The generation time of some species may be as little as 24 hours under favorable conditions.  This will quickly overwhelm a host population.

Effective treatment of these parasites depends on an understanding of the two major types of lifestyles:  nonencysting and encysting.

Another type of parasite is living worms in the internal organs of the host, especially the intestines, swim bladders, peritoneal cavities, and even the gonads. Most of them have a very complicated life cycle.

Nonencysting Protozoan – Attached to gills, fins, in muscle tissue, and on skins (e.g., Trichodina, Ichthyobodo or Costia necatrix) and complete their life cycle on the host and are easily treated, usually with a single short-term drug application. However, if the infections are found in the internal organs, the treatment can be difficult and unpredictable.

Encysting Protozoan – The feeding stage feeds in a nodule formed in the skin or gill epithelium and when mature they break through the epithelium, fall off the host and form an encapsulated diving stage known as a comment which secretes a sticky capsule.

These reproductive capsules adhere to plants, nets, ornaments, and any object found in the aquarium.

They multiply by binary infusion and within 8 to 24 hours, large numbers of new swarmer cells are formed. They then break through the nodules (or cyst) and actively swim for a new host fish.

The reproductive cysts (e.g., Ichthyophthirus,   Amyloodinium) are resistant to treatment, so therapy must be directed at the free-swimming, infective stage.

This requires that drugs and chemicals be present for a longer period or requires several treatments to be applied to ensure that all infective stages are destroyed.

DIAGNOSIS:   There are more than 60,000 known types of parasites, which affect the health of living things on earth.  Several types of parasites also plague aquarium fish, which makes fish keeping a real nuisance.  We will deal with some of these which are commonly encountered by the Aquarius.

Unicellular (Protozoa):

CHILODINELLA – infects gill mostly – whitish or bluish sheen on body, “tattered” appearance to skin – feed by penetrating the host cells or directly on epithelium – advance infestations cause skin ulcers, sliminess of the skin and secondary bacterial infections and death.

TRICHODINA – High mortality if infects small and baby fishes – attacks marine and freshwater fish – infest both skin and gills – fish rub and scratch themselves against rocks and plants or jerk violently with their fins.

COSTIA – also known as Ichthyobodo necatrix  – White-Coat diseases – bluish or whitish film on the body – penetrates, the epithelium causing tissue irritation.  Also leads to epithelial hyperplasia and increase mucus production.

ICHTHYOPHTHIRIUS  MUTIFILIIS (White sports diseases – Ich) – The most common disease of freshwater fish.  Virtually all freshwater fish are susceptible to this infection, although scale-less fish, such as catfish and loaches are especially vulnerable with a possible 100% mortality rate.  They appear as white cysts or salt-like dusting on the skin, fin, and gills.  A common temperature for ich outbreaks is 150 C to 250 C and complete their life cycle in 3 to 6 days.

OODINIUM – MARINE (amyloodinium) and FRESHWATER (piscinoodinium)  (red -velvet diseases) – Both diseases have golden, dust-like sheen (velvet) on the skin.  The life cycle is the same as for Ich but completed in 10 to 14 days under optimal conditions.

GILL FLUKES  (Dactylogyrus)  – a monogenean infection that attacks mainly the superficial layers of the gills and causes the fish to suffer dyspnea and hypoxia.

SKIN FLUKES (Gyrodactylus) – another common monogenean infection, but this disease causes cloudiness to the skin, grey-white caste or irregular areas on the skin, eroded fin, focal hemorrhages on the skin, and incite excess mucus production or pruritus.

FLAGELLATE PROTOZOA – (Hexamita or Hole-In-The-Head Disease) – This disease mostly affects cichlids such as Angelfish, Discus, Oscars, large South American Cichlids, and even Gouramis.

Almost all known information regarding this disease is based on popular aquarium literature and there are no published scientific reports.  Some aquarium experts believe that the diseases are caused by a mineral imbalance that results in skeletal damage leading to pitting lesions.  Some claim that the disease is due to the lack of vitamin C in a normal diet.

Some speculate that a heavy concentration of flagellates in the intestine can cause malabsorption, leading to mineral imbalance.

Another hypothesis is that a Hexamita-like flagellate, which is present as a latent intestinal infection, spreads by both extension and hematogenous to the gall bladder, peritoneal cavity, spleen, kidney, and associated vasculature.  In later stages,  the hole-in-the-head lesions appear, first as pinpoint lesions that may discharge small,  white short “threads” of material containing the parasites and looks like a white worm.  The pinpoint lesions become bigger as time goes on and maybe as big as several millimeters across.  Secondary infections such as bacteria and fungi may set in and the ultimate cause of death may be secondary microbial infections.

2. Complex Parasites:

These Groups Of Parasites attack the host either externally or internally or both.  Most are introduced into the aquarium from wild or pond-raised fish and mostly from live food such as tubifex worms and live plants.

We only look into a few that commonly affect the freshwater aquarium keepers.


LICE ( Argulus) – A saucer-shaped crustacean that affects mostly Koi and gold fish.

Attack by inserting a pre-oral sting (stylet) into the host and sucking body fluid or blood with its sucker mouth.  Fish display violent erratic swimming and other abnormal behavior because of the skin damage caused by the repeated piercing of the skin by the stylet which injects toxic enzymes, causing irritation.  Focal red lesion and focal darkening of color on the skin.

ANCHOR WORM (Lernae) – A lernacid copepod that possesses anchor-like processes for securing itself to the host.  Koi, Goldfish, and carp are most commonly affected.  Various sized (from barely visible to about 10 mm) copepods attached to the oral cavity, gill arches, or skin; erosion or ulceration; red area on the skin, may be raised up to 5 mm in height.

LEECHES – A parasitic species of annelids having a complete digestive tract with a

mouth in the anterior sucker and an anus in the posterior suckers. They are hematophagous and suck blood even during the night.  Hosts usually suffered severe chronic anemia, small red or white lesions on the skin and some can cause large ulcers on the skin and in the mouth.


TAPEWORMS (CESTODES) – Usually appear as a white, elongated, tangled piece of segmented ribbon-like string and may grow up to several centimeters long.  In the case of heavy infestations, the fish may become emaciated with heavy worm burdens with some parasites protruding from the vent.  By then the adult worm may have already infested the peritoneal cavity, liver, or muscle and the intestine, which may become obstructed or perforated.

ROUNDWORM (NEMATODE) – The adult forms are normally found in the digestive tract where some can cause chronic wasting if present in high numbers.  Heavy infestation emaciates the host, producing a sharp ridge under the dorsal skin.  The adult worms’ bodies are thin, unsegmented, round, spindle-shaped, or thread-like cross-sections.

PINWORMS or TREADWORMS (OXYURIDA) – These worms, experts claimed affect only the discus.  They feed on the intestinal contents and damage the host by depriving nourishment of them.  The host becomes timid, darkens, and finally wastes away.



Luckily for the fish hobbyist, the treatment procedure for most parasite infections in this classification is all the same:

  1. If the parasites are visible ,first remove them carefully with a surgical forceps.  Pull out slowly but some may still  have their head embedded in the epithelium.  Dab the affected area with undiluted Rid-All Anti-Fungus or lotion Potassium permanganate 1:1000
  2. Use Rid-All Copper Aid at normal dosage for one day.  Add Rid-All Anti-Ich on the next day.  On the 3rd day displace 25% water and add Copper Aid and Anti Ich together at normal dosage of 5 ml to 25 litres for both types. Keep a good look out on the 4th day and 5th day.  If there is sign of improvement repeat the procedure on the 6th day.  If there is no improvement at all, change to one of the following treatments.
  3. Malachite Green 0.75% in formalin 40%.  Use 2 drops for five litres as bath for 3  days.
  4. Most effective treatment for nonencysted nematodes – Levamisole Hydrochloride at the dose of 10 mg per litre for prolonged immersion.
  5. The best treatment is to use a pesticide or insecticide known as Dimilin manufactured by Union Carbide Company also known as Diofluorobenzuron.  Usually one dose of 1 gm in 1000 Gallons of water is more than enough to kill all Lice and Anchor worm in one single prolonged bath.  Unfortunately you may need a permit to use it.
  6. Another popularly used Insecticide is an Organophosphorous known as Trichlorfon or Masoten or Dipterex.   Same dosage as Dimilin but much more toxic to fish and the applicator.  When added to water Trichlorfon degrades to the more toxic Dichlorvos (DDVP).  Both can cause neurotoxic poisoning in humans. So avoid inhalation or absorption through the skin.  This item is available from flowers and nurseries shops.  The liquid form is very unstable and if the solvent is water, the potency is less than one week. If the powder looks wet, lumpy or translucent it has degraded to the toxic Dichlorvos and should not be used. Therefore if you buy a liquid form of Trichlorfon make sure you buy a reputable products such as the Neguvon (an 8% Trichlorfon in a specially prepared solution) otherwise you are wasting your  money and time.  This item may also need permit to use in some countries.


The most efficient way to treat internal parasites is to feed the fish orally with the drugs.

The following drugs are used in order of my preference for all known internal parasites

  • Praziquantel at 50 mg. per kilo of body weight per day.  One dose is enough to clear the body of adult cestodes, monogeneans, and possibly larval digeneans.
  • Mebendazole at 1 mg. per litre as long bath for 24 hours
  • Fenbendazole  at 25 mg. Per kilo of body weight for 3 days and repeat one week later.

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