Antiseptics and disinfectants in aquaculture can be accepted alternative in minimizing use of antibiotics, if they meet maximum efficiency and minimum impact on fish health and the environment.

1. R. K. Brahmchari
Assistant Professor
College of Fisheries, Dholi
(RPCAU)
Muzaffarpur, Bihar
Antiseptics
& Disinfectants
in Aquaculture

2. Definition
Antiseptics are used to kill or eliminate
microorganisms and/or inactivate virus on living
tissues (intact or broken skin and mucous
membranes).
Disinfectants are used to kill or eliminate
microorganisms and/or inactivate virus on inanimate
objects and surfaces (devices, instruments,
equipment, walls, floors, ponds, tanks).
Certain products are used both as an antiseptic and
as a disinfectant

3. Context to Aquaculture
Different approaches has been tested with more and
less success to avoid disease appearance and spread
in Aqua hatcheries, ponds and nurseries.
One way is to employ anti-infectives for preventive
and curative purposes, to avoid use of antibiotics in
aqua practices.
In that context, older anti-infectives like
disinfectants and antiseptics could be again
observed with full of interest….

4. CLASSIFICATION OF ANTI-INFECTIVES
1. Anti-infectives with unspecific mode of action:
 Disinfectant
 Antiseptic
2. Anti-infectives with specific mode of action:
 Antibiotic
 Antifungal
 Antiviral
 Antiparasitic

5. COMMON CHARACTERISTICS
 Substances which inhibit or destroy various micro-
organisms, mainly bacteria and fungi, eventually
virus and parasites.
 By an unspecific action
 Working at high concentrations
 Characterized by a quick and short action,
 Owning a general toxicity that is to high for an
internal use in animals.

6. Distinction between DISINFECTANT & ANTISEPTIC
 This is mostly a difference of use, as the majority of
these molecules is employed for both : antisepsis and
disinfection; this is often a difference of concentration.
 Some disinfectants are strictly reserved for inert
materials because they are too toxic for living
organisms, even in external administration.
Disinfectants :
reserved for inert materials
(premise, rearing equipment),
Very high concentrations of
active ingredient(s)
Antiseptics :
reserved for an external
administration on animals,
High concentrations of active
ingredient(s)

7. Screening of Antiseptic & Disinfectant
used in Aquaculture
IMPORTANT CONSIDERATIONS
 Goal? SANITIZATION and not sterilization
 Destruction of pathogens in priority
 Keeping other agents at a small & harmless level.
CRITERIA OF SELECTION
 Efficacy
 Safety
 Ease of use
 Cost

8. 1. Pond/ Topical Disinfectants
1.Lime
 Liming is considered an integral part of pond management.
 These include improvement of soil chemistry – like ↓ soil
acidity, ↑ total alkalinity, neutralizing sulfides and acids,
precipitating suspended organic material, ↓ BOD, and
improving nitrification
 There are several types of lime that are used in grow-out
ponds - most common is Agricultural lime (CaCO3).
 To disinfect, 100-300 kg/ha is applied in fish ponds during
the culture period

9. 2. Formalin
 Formalin has a very old history as an aquatic chemotherapeutant.
 The first recorded use of formalin in the treatment of fish disease
was in 1909 (Alderman and Michel 1992).
 Formalin kills microorganisms by condensing with amino acids to
form azomethines.
 It is active against a wide range of organisms, including fungi,
bacteria and ectoparasites.
 However, its action is slow.
 At a concentration of 5,000 ppm, 6-12 h is required to kill bacteria
and 2-4 d to kill spores.
 It is also ineffective againstinternal infections.
 Formalin has been approved by most of countries including US
FDA for use in treatment of food fish.

10.  The recommendeddosage rates are 150 ppm for a 1 h bath
and 25ppm for long-term treatment.
 Formalin is also applied directly in ponds at rates varying
from 10-25 ppm, especially during protozoan outbreaks, as a
cure-all remedy.
 However, formalin also causes oxygen depletion and this
excess can be deleterious in the long run

11. 3. Benzaklonium Chloride (BKC)
 BKC is a cationic compound that, like formalin, is toxic to a
wide range of bacteria, fungi, and viruses.
 Unlike formalin, it is non-irritating to tissue and has a rapid
onset of action.
 BKC has been recommendedas a bactericide and fungicide
in hatcheries.
 Suggested dosages are 1-1.25 ppm.

12. 4. Acriflavine
 Acriflavine is a mixture of 3,6-diamino-10-methylacridinium
chloride and 3,6-diaminoacridine, Known also as
Trypaflavine.
 It has been used extensively in egg disinfection; as an
antiseptic for treating wounds, ulcers, and bacterial lesions;
and in protozoan and monogenean infections.
 Acriflavine is normally used as a long-term bath and is
known to kill plants.

13. 5. Malachite Green
 Malachite green is the common name for p,p-
benzylidenebis-N,N-dimethyl aniline.
 It was originally developed in the 1920s as a textile dye.
 Malachite green has been extensively used in controlling
infections due to bacteria, fungi, protozoans and
monogenetic trematodes on eggs, fry and adult fish.
 In recent years, however, there have been strong moves
against malachite green application, especially with respect
to its use in food fish.
 This is because the chemical has a moiety that is known to
be carcinogenic.

14.  It is usually applied at 1-2 ppm for short exposure, and for
long baths at 0.01 ppm for fry/fingerling/PL and 0.1 ppm
for juveniles.

15. 6. Hypochlorite
 Both sodium and calcium hypochlorites have a long tradition
of use in the aquaculture industry.
 Hypochlorites act by releasing hypochlorous acid, which is
the primary active ingredient.
 Hypochlorites are potent germicidal agents.
 They are particularly effective in acidic conditions. For
example, the bactericidal effect of hypochlorite is 10 times
greater at pH 6 than at pH 9.
 At pH 7.0, a 0.1-0.25 ppm hypochlorite solution will kill most
organisms within 15 to 20 sec.

16.  Hypochlorites are too toxic to be used directly on tissues
and therefore cannot be used for treatment or prophylaxis.
 Both products, however, are used extensively as
disinfectants.
 In ponds, hypochlorites have been traditionally used as
piscicides. However, a more recent use has been their
application to disinfect incoming water.

17. 7. Polyvinyl Pyrrolidone Iodide (povidone-iodine)
 Polyvinyl pyrrolidone iodide (PVPI) is an iodophor
compound sold under the name Betadine .
 An iodophor compound is basically a complex of iodine
with a solubilizing agent or carrier that liberates free iodine
in solution.
 Iodine, like chlorine, is a halogen and has a strong oxidizing
capability.
 It is lethal to microflora and to viruses, which are killed
within 15 min in a 50 ppm solution

18.  Like chlorine, PVPI can be used only for disinfection and is
too toxic for treatment or prophylactic purposes.
 However, it has a much lower toxicity as compared to
chlorophors (such as hypochlorite) and thus can be used to
treat eggs of shrimp and fish.
 Even a solution as dilute as 10% PVPI will exert adequate
bactericidal action in the presence of organic matter.
 Used as a fish egg disinfectant at rates of 50 mg/L for 30
minutes during waterhardening and 100 mg/L solution for
10 minutes after water hardening.

19. 8. Zeolite
 Zeolite is often used by fish and shrimp farmers to improve
pond bottom condition.
 This is related to its capacity to absorb ammonia and
metabolites from water.
 However, the efficacy of zeolite in this respect diminishes
with increasing hardness.
 Recommended doses for Pond preparation: 50 kg/ha;
during culture: 10-20 kg/ha

20. 9. Copper Sulphate
 Copper sulphate is a broad-based disinfecting agent used in
fish/ shrimp farms.
 It is effective against a wide range of organisms including
blue-green algae, bacteria, fungi, protozoans, digeneans,
leeches and monogeneans.
 Copper sulphate is used at a rate of 1:2000 with water/acre
or 0.5 ppm in freshwater ponds.

21. 10. Potassium permanganate (KMnO4)
 KMnO4 , is a oxidizing agent that will react with any organic
matter in a pond including algae, bacteria, fish, and organic
bottom sediments.
 It has been used in fish ponds to treat common fish
pathogens such as gill parasites and external bacterial and
fungal infections.
 Contrary to some reports, KMnO4 does not add significant
amounts of oxygen to water and actually decrease dissolved
oxygen concentrationsby killing algae that produce much of
the oxygen in ponds.
 Common treatment rates are 2 ppm or mg/L for an
indefinite pond application or 10 mg/L for a 10-minute tank
treatment.

22. 11. Organophosphates
 Organophosphate pesticides are used in both freshwater fish
ponds and marine shrimp hatcheries to control infections by
crustaceans, and monogeneans and ciliates, respectively.
 The main organophosphatesused are Malathion, Dipterex,
Dichlorvos, and Dursban.
 In many freshwater fish farms, these organophosphates are
also used to control aquatic insects that prey upon fish fry,
such as dragonfly larvae.
 Dosage is usually about 0.5-1 ppm for 3 to 7 day.

23. 12. Sodium chloride (Salt)
 Used as a 0.5-1% solution for an indefinite period as an
osmoregulatory aid for the relief of stress and prevention of
shock.
 Used as a 3% solution for 10-30 minutes as a parasiticide.