Chloramine / Halamid in aquaculture

Halamid® in aquaculture (Chloramine-T trihydrate)

Buy a 1 kilogram pack at the Ecotao shopping site.

Aquaculture requires strict hygiene rules to prevent diseases resulting in fish welfare problems and heavy economical damages. Halamid®, also known under its generic name chloramine-T in this market, is the internationally accepted product for hygiene in the aquaculture farm. Very effective against fish and shrimp pathogenic microorganisms, it has proven already for many years to be an indispensable product in any aquaculture operation, from the nursery and growing tanks to the fish processing plant.

See this article on the use of Halamid with fish

“Can Halamid be used in the presence of fish?

Yes, Halamid has the unique feature that it can be used as disinfectant in presence of fish.

Fresh water raceway set up:

Halamid® is added at a concentration of approximately 10-20 ppm (10-20 g/m3). After 1 hour, flush with fresh water to remove residual Halamid®. This can be repeated up to 4 times on consecutive or alternate days.”

The safety margin between the concentration effective against microorganisms and the one toxic for fish makes Halamid® of special interest in aquaculture. Well known applications of Halamid® include use against pathogenic bacteria, such as the ones responsible for Bacterial Gill Disease (BGD) or external columnaris. Halamid® is also useful against many parasites related to the aquaculture industry, for example the Gyrodactylus and Neoparamoeba pemaquidensis (Amoebic Gill Disease) parasites.

Aquaculture needs a universal and versatile disinfectant in order to ensure the best health and hygiene status. Disinfection with Halamid® of tanks and ponds, nets, equipment, well boats and in the fish processing industry ensures that pathogenic microorganisms (bacteria, viruses and parasites) are rapidly and effectively destroyed.






Tank and pond disinfection

1% – 2%


Equipment disinfection



Net disinfection



Well boat disinfection





Renew as often as needed

Water treatment – Fresh water raceway ponds

10-20 mg for 1 hr

Can be repeated up to 4 times of consecutive or alternate days

Water treatment – Stagnant water ponds

3 ppm once a week


General disinfection in the aquaculture farm

Always remember that cleaning is a required preliminary step before disinfection to ensure the best results. Without proper cleaning, dirt and organic matter protect microorganisms from the disinfectant, resulting in an incomplete operation.

Start by dry cleaning to remove most of the organic matter, followed by cleaning either with water or a detergent solution. Once this is done, disinfect with Chloramine-T / Halamid®. Halamid® is always applied as a water solution: simply dissolve the Halamid® powder into clean water at the required concentration.

Tanks and equipment disinfection

Tank disinfection

During the production stops, it is of major importance to thoroughly clean and disinfect the tanks and ponds when they are empty to avoid contamination of the next production lot. Start by cleaning to remove the organic matter and then disinfect by spraying or rinsing with a 1% Halamid® solution (or with a 2% in case of contamination with resistant microorganisms).

Equipment disinfection

All equipment used in an aquaculture farm should be sprayed with a 0.5-1% Halamid® solution (or with a 2% in case of contamination with resistant microorganisms) or dipped into a similar solution for 30 min.

Net disinfection

Aquaculture nets should not only be cleaned between each production cycles but also disinfected. Compatibility of aquaculture net made of Polyamide 6 with a Halamid® solution was tested by a polyamide manufacturer and the results indicate that Halamid® does not have any negative effect on the net mechanical characteristics. A 1-2% Halamid® solution should be used for net disinfection, with a contact time of 30 min.

Vehicle disinfection

Vehicles are an important way of disease transmission from farm to farm. Make sure all vehicles are well disinfected (not only the wheels) with a 1% Halamid® solution prior entrance to the farm. Equipment used for fish transports or that has been in contact with infected fish should be dried, frozen or disinfected (e.g. in 1% Chloramine-T [Halamid]).

Well boat disinfection

Insufficient well boat disinfection is believed to be responsible for spreading of several pathogenic microorganisms, including the IPN virus in Norway. This underlines the need to apply a strict hygiene management on well boats.

Well boats must be disinfected with a 1-2% Halamid® solution between each transport. Rinsing with water may be required to remove residual Halamid®.


A footbath should be placed at the entrance of each building and you should make sure everybody is using it. A 2% Halamid® solution must be prepared and refresh as often as needed. Additionally, you can also have shoes available for visitors at the farm entrance and place them in a 1% Halamid® solution (to be renewed weekly) at the end of the day.

Water treatment

The efficacy of Halamid® reduces the pathogenic microorganisms level in ponds water and is especially useful against bacteria responsible for the Bacterial Gill Disease.

  • Chloramine T is used to control mortality in fishes diagnosed with Bacterial Gill Disease (BGD) (Flavobacteria branchiophilum and other external flavobacteria) and
  • External flavobacteriosis (External flavobacteria, caused by F. columnare, F. psychrophilum, and other  closely related yellow-pigmented gliding bacteria are often collectively termed external flavobacteriosis€).
    • 1 hour static bath or flow through Chloramine-T treatment.
    • Chloramine-T  may be administered at 10, 15, or 20 mg/L Chloramine-T, and fish may be  treated 1 – 3 times on alternate or consecutive days.
  • antiseptic and odor control agent. It can also eradicate parasites  and bacteria when cleaning tanks and equipment.
  • Chloramine-T is stable  in aqueous solutions for many months when kept in the dark.
  • Can inhibit nitrification and should not be used in systems with a biofilter unless the biofilter is taken offline
  • Use to control mortality:
    • Due to BGD in all freshwater-reared salmonids
      • 12 -20 mg/L for 60 min/d on 3 alternate or consecutive days
    • Due to external columnaris in walleye
      • 10 -20 mg/L for 60 min/d on 3 alternate or consecutive days
    • Due to external columnaris in all warm water finfish
      • 20 mg/L for 60 min/d on 3 alternate or consecutive days
  • readily biodegradable, has none of typical chlorine properties, so safe to the environment
  • effective on a whole range of  micro-organisms, including Gram-negative and Gram positive bacteria,  fungi and naked virus and enveloped viruses.

Fresh water raceway set up

Note that this is done BEFORE and fish are added to the tanks! Halamid® should be added at a concentration of approximately 10 ppm (10 g/m3). After 1 hour, flush with fresh water. This can be repeated up to 4 times on consecutive or alternate days.

Stagnant fresh water ponds

Halamid® should be added at a concentration of 3 ppm (3 g/m3) once a week.

Water pH and hardness are two important parameters to consider in order to optimize the Halamid® concentration. As a general rule, with acidic pH, a lower concentration should be used and with increasing water hardness, a higher Halamid® concentration is recommended.

Also if using a biofilter to purify recirculated water, special attention must be taken. Please contact us or your distributor for more detailed information.

Artemia disinfection

Halamid® is recommended by the FAO (Food and Agriculture Organization) for disinfection of Artemia nauplii at the concentration of 60 ppm with a contact time of 3 min followed by rinsing with clean water. (Health management and biosecurity maintenance in white shrimp (Penaeus vannamei) hatcheries in Latin America, FAO, 2003)


“Chloramine T is the active ingredient of Halamid.

We have tested a US manufactured brand (trade name Halacon) and noted the following:

For Artemia: add 30 ppm at the time that the cysts are being added for
hatching. It eliminates most of the bacteria.

For nauplii: early stage nauplii are very sensitive to the effects of this
and we do not suggest that it be used until N4 or later. They can tolerate a high level (100 ppm for 30 sec). This appears to eliminate all of the  bacteria that might be surface  associated with the nauplii. Iodine eliminates about 50%.

For PLs: add to the hatchery tanks to 6 ppm daily to prevent filamentous bacterial problems. 

 Stephen G. Newman Ph.D.

Fish egg disinfection

To reduce surface contamination, fish eggs can be dipped in a 1 g/l Halamid® solution for 10 min followed by a clean water wash.

Chloramine Fish treatments

Chlorine dioxide (at 25ppm) and Chloramine T (HalamidTM) (at concentrations between 10 and 25ppm) are potential candidate additives in freshwater baths to be more effective in killing Neoparamoeba and removing offensive parasite from the gills of AGD affected salmon. A preliminary cost analysis suggests that Chloramine T is a favored treatment due to lower cost. Chloramine T at 1 hour bath was effective even in seawater and was as effective as at 3 and 6 hours bath.

Control of mortality in freshwater-reared salmonids due to bacterial gill disease associated with Flavobacterium spp.

Use at concentrations of 12 to 20 milligrams per liter water [mg/L;  equivalent to parts per million (ppm)] in a continuous flow water supply or as a static bath once per day for 60 minutes on consecutive or  alternative days for three treatments in fish culture units (ref: ).

Control of mortality in walleye due to external columnaris disease associated with Flavobacterium columnare

Use at concentrations of 10 to 20 milligrams per liter water [mg/L;  equivalent to parts per million (ppm)] in a continuous flow water supply or as a static bath once per day for 60 minutes on consecutive or  alternative days for three treatments in fish culture units.

General disinfection in the fish processing plants

Halamid® is very useful for disinfection in the fish processing plants. For more information about this application, please refer to the specific bulletin on Halamid® in the food industry.

Fish hobbyists (koi keepers / hobbyists, etc.)

Halamid® is widely used by fish hobbyists against external bacteria and some parasites. It is for example particularly useful against external flukes in koi fish. Here again water hardness as well as pH are two important parameters to consider in order to adapt the concentration to your own conditions.

Halamid® is also of special interest for general disinfection of tanks and equipment in order to minimize as much as possible risk of bacterial or viral contamination



  • ingredient: Sodium p-toluenesulfon chloramide
  • treatment:
  • use: Bacteria, bacterial gill disease, gill fluke, protozoa, white spot
  • dosage: 30mg/l (30 grams per 1000 liters)
  • duration: 30 minutes
  • comment :  
  • formula: Sodium p-toluenesulfon chloramide
  • reference :

Fish with parasites, bacteria or blockages of the gills will distend their gill covers out wider and breathe more rapidly than normal to obtain oxygen, before dying. Low levels of dissolved oxygen in the water, in contrast, usually cause the fish to sip repeatedly at the surface.

Careful examination of a few sick or very recently dead fish will help identify the case. If well-defined segments of the normally red gills are white or off-white and slimy, the most likely cause is Bacterial Gill Disease. This is due to an overgrowth of common water bacteria and flexibacteria, which usually occurs following cold snaps or temperature stress, and in crowded unhygienic conditions. These stressful conditions should be removed, then the fish can be treated with Halamid / Chloramine, at 10 mg of active ingredient per litre of water, for 24 hours (ref).


Halamid® is effective against many microorganisms related to aquaculture applications. A few of them are indicated below, but the complete activity spectrum of Halamid® is much wider.


Aeromonas salmonicida (Furunculosis)
Flexibacter maritimus (Marine columnaris)
Flavobacterium branchiophilum (BGD)
Flavobacterium columnaris (Columnaris)
Vibrio anguillarum (Vibriosis)
Vibrio harveyi
Vibrio salmonicida
Vibrio parahaemolyticus
Yersinia ruckeri (Redmouth disease)
Escherichia coli
Salmonella typhimurium
Bacillus subtilus spores


Infectious Pancreatic Necrosis (IPN)
Infectious Salmon Anaemia (ISA)


Gyrodactylus salaris
Ichthyobodo necator (Costia)
Ichthyophthirius multifilis (White spot)
Neoparamoeba pemaquidensis (Amoebic Gill Disease)
Aspergilus fumigatus
Trichphyton equinum

Trematodes & parasites

Halamid® is recommended by the OIE to disinfect equipment against Gyrodactylus salaris at 1% and is also recognized by the same organization to be effective against IPN and ISA viruses.

  • Gyrodactilus salaris
  • Epistylis
  • lchthyobodo necator
  • lchtyophthirius


Toxicity of Halamid® to numerous aquatic species (fish and shrimp) has been established, to ensure safety of Halamid® applications.



Chloramine-T (C7H7CINNa02S. 3H20)

98% w/w (minimum)

Calculations and additional data

For Static Bath Treatment:

HALAMID® needed (grams) = Volume of water to be treated (liters) (gallons) X Treatment Concentration (ppm or mg/L) (X 0.0038 (gallon correction factor1))

e.g. 10ppm in 1000 liters = 10 grams per 1000 liters. (10 x 1000 = 10,000 mg; divide by 1000 = 10g)

For Constant Flow (flow-through) Treatment:

HALAMID® needed (grams) = Water Flow liters per minute (Gallons per minute) X Treatment Duration (minutes) X Treatment Concentration (ppm or mg/L) (X 0.0038 (gallons correction factor1)

e.g. 10 x lpm x 60 minutes x 10 ppm = 6000, divide by 1000 = 6g additional for duration to compensate for additional water (see below explanation)

1Correction (or conversion) factor is equal to:

3.785 L/gal


1000 mg/g


1. STATIC TREATMENT: Shut off water flow to culture unit before adding drug. Completely dissolve HALAMID in a separate container of culture water and thoroughly mix into  the culture unit. The drug solution should be used immediately and not  stored. End treatment by flushing system with fresh water. Resume normal flow.

2. CONTINUOUS FLOW TREATMENT: Determine flow rate for culture  unit. Pre-charge culture unit by administering the amount of drug needed for a static treatment. Meter additional drug solution into culture  unit at a concentration and rate necessary to maintain the target dose  in the culture unit for the duration of the treatment period (see above for calculations).

In aquaculture disinfection is split in two different applications:

Surface disinfection

Surface disinfection is carried out after thorough cleaning. In many countries there is a tradition to combine cleaning and disinfection. Chloramine T can likewise be dissolved in a solution of a preferably neutral- detergent (pH between 6-8). It should be borne in mind that most of the times a one-step treatment is only partially successful. Best results are attained if “dirt” (interfering proteins and encapsulating fatty matter) is first removed so that the disinfectant is able to have an optimum contact with the micro-organisms still clinging to the surfaces thus treated.

Chloramine T can be rinsed, brushed, mopped or sprayed. Spraying devices should use a pressure below 10 bar to produce coarse droplets. This avoids the risk of inhalation and promotes a proper distribution of the active solution. Non-porous surfaces require at least 150 ml of fluid per M2. Higher temperatures of the disinfecting solution are only useful if the materials to be treated are allowed to adopt these temperatures themselves (e.g. in laundering). Allow the treated surface to dry to the air.

Water disinfection

Water disinfection is done to bring or keep the microbial quality of the water to a certain desired level, by simply adding Halamid to the water in the required amount. This is the application where Halamid shows one of its unique properties: the simple applications and the broad range activity combined with the low toxicity of Halamid to fish and shrimps. This means Halamid can be used both for water pre-conditioning (without fish or shrimps in the water) and water quality maintenance.(in the presence of fish or shrimps) This is the best way to grow strong and healthy animals in each stage, resulting in reduced mortalities and increased profits.


At the hatchery level Chloramine T can be used to disinfect a.o.:

Disinfection Procedure

Broodstock tanks   

Tank water – for pre-conditioning

Fish eggs


Feed i.e. Artemia 

Waste water   


At the nursery level Chloramine T can be used to disinfect:

Disinfection Procedure

Nursery tanks  

Tank water – for pre-conditioning  – for quality maintenance


Feed i.e. Artemia

Fish fry


Waste water      

Grow-Out Farm

At the grow-out level Chloramine T can be used to disinfect:

Disinfection Procedure


Pond bottom

Pond water  – for pre-conditioning

                     – for quality maintenance


Waste water

Processing Plant

In the processing plant Chloramine T can be used to disinfect:

Disinfection Procedure



Transport vehicles                               

Waste water                                       

Disinfection Procedure reference

The disinfection procedures mentioned in the Application paragraph are listed below:

1.       Spray, flush or mop with a 20 g Chloramine T/litre solution. After 30 minutes wash with clean water.

2.       Add 15 g Chloramine T per cubic meter water. Wait at least 24 hours before further treatment.

3a.     Dip in a 1 g Chloramine T per litre solution for 15 minutes. Then wash with clean water. (procedure proven to be effective with plaice, cod and halibut eggs)

3b.     Dip in a 50 mg Chloramine T per litre solution for 15 minutes. Hatch in a solution containing 3mg Chloramine T per litre. (procedure proven to effective with grouper, milk-fish and sea-bass eggs)

4.       Spray, flush or mop with a Chloramine T solution of 3 g/1. If necessary wash with clean water after 30 minutes.

5.       Wash for 15 minutes with a Chloramine T solution of 1 g/1. Then wash with clean water.

6.       Add Chloramine T to a concentration of 15 to 50 g/m3 (depending on the organic contamination present). Discharge after 24 hours.

7.       Dip in a Chloramine T solution of 100 mg/1. After 15 minutes wash with clean water.

8.       Dosage and result strongly dependent on actual conditions. Assistance is available on request.

9a.     For race way set up. Add Chloramine T to the tank/basin at a concentration of 10 gram per cubic meter. After 1 hour flush with fresh water.

9b.     For stagnant water ponds. Add 3 gram Chloramine T per cubic meter once a week.



To obtain the optimal surface disinfection results, the surfaces should be almost, but not completely dry at the moment the disinfection operation starts. If the surfaces are too wet instant dilution (lower activity) will occur. If the surfaces are completely dry more Chloramine T solution than strictly required is needed. Allow the treated surface to dry to the air. Unlike cleaning, the disinfection effect cannot be checked visually. Therefore you need a methodical approach to ensure the best results.

Chloramine T is always used in aqueous solutions which are prepared by dissolving the powder in water. Chloramine T is a mild product without any immediate harmful effect on the human skin, the eyes or clothes, but it should not be inhaled or allowed to act on the skin for many hours at a stretch. A dust mask is recommended when a solution is prepared. In case of skin contact the skin section exposed must be washed with water and soap.

Chloramine T itself does not produce foam, but it can very well be used in foaming devices for marking off the surfaces that have to be disinfected. For vertical surfaces using a foam containing Chloramine T adds to the efficacy of the disinfectant solution.


In most of the above mentioned applications Chloramine T is used as a disinfectant and falls under the existing local legislation for disinfectants. However in water quality maintenance, other legislation may be valid because here direct contact of Chloramine T and the life fish or shrimp takes place. To a minor extend the same is true for the treatment of eggs; fry, post-larvae, and artemia.

In the USA Akzo Nobel sponsors a project in cooperation with the Food and Drug Administration, FDA, to obtain a New Animal Drug Approval, NADA, for the use of Chloramine T in fish farms. Field trials are now running for the second year proving the efficacy of Chloramine T for the treatment and/or prevention of bacterial diseases. Residue studies have shown that fish treated with Chloramine T after two weeks no longer contains any traces of Chloramine T or of its metabolites.

In Europe Akzo Nobel is cooperating with farmer organizations and the ECU authorities to come to legislation with respect to the use of Chloramine T in fish farming. This is part of a broader effort to regulate chemicals used in aquaculture.


Extensive toxicity testing shows that Chloramine T can be classified as a disinfectant with low acute toxicity. Its LD~. in rats and mice is 1000 mg/kg. The 90-day-No-Effect-Level (NOEL) in rats is 15 mg/kg/day.

Chloramine T is readily biodegradable, is not adsorbed by soil and sludge and does not show any bioaccumulation.

The unique mode of action of Chloramine T (no chlorine or hypochlorous acid as intermediate) makes the question of formation of chlorinated organic compounds (AOX) irrelevant.

Toxicity to Aquatic Species

The toxicity of Chloramine T to the following species relevant to fish and shrimp farming has been established in tests:

Daphnia Magna (water-flea)                                             48-hour NOEC              
1.8 mg/l

21 -day NOEC               1.1 mg/l

Poecilia recticulata (Guppy)                                            96-hour NOEC              
1.2 mg/l

Lebistes recticulatus (Gold guppy)                                   48-hour NOEC              
20 mg/l

Pimephales promelas (Fathead minnow)                          35-day NOEC               
1.5 mg/l

96-hour LCSO                7.3 mg/l

Salmo gairdneri (rainbow trout)                                       
1 -hour NOEC               
100 mg/l

8hour NOEC                 
50 mg/l

24-hour NOEC              
10 mg/l

96-hour LC50                
2.8 mg/l

Ictalurus punctatus (Channel catfish)                               96-hour LCSO               
3.8 mg/l

Rasbora heteromorpha (Harlequin fish)                             48-hour LCSO               
1.8 mg/l

Rutilus rutilus (Roach)                                                    48-hour LCSO               
60 mg/l

Penaeus setiferus (Gulf white shrimp) (mysis stage)         24-hour LCSO               
20 mg/l

Penaeus stylorostris Post-larvae (30-50 mm)                    72-hour NOEC              
10 mg/l

Penaeus monodon (Giant tiger shrimp)                            24-hour LC5O               
100 mg/l

Artemia (Brine shrimp) (nauplii)                                      
72-hour NOEC               10 mg/l

72-hour EC5O                25 mg/l