Aqua Medicines for Sustainable Fish Farming

Posted by HANGSHAKALI CHAKRABORTY on

Aqua Medicines for Sustainable Fish Farming

Himadri Saha and Mukta Singh

College of Fisheries, Central Agricultural University (I), Lembucherra, Tripura, India

1. Introduction

    Global aquaculture has grown drastically in the previous 50 years to around 106 million tonnes in live weight, which comprises of farmed aquatic animals, aquatic plants and non-food products (pearls and shells). At present, India is the second largest producer of aquaculture in the world (DADF, 2016) and the country has plans to increase the annual growth rate mark by 8 percent in coming years by 2020 (Press Information Bureau, 2017).

    Vertical expansion is the ultimate way out as the scope for horizontal expansion is very limited. However, the vertical expansion of aquaculture practices with the introduction of diversified species and higher stocking density has resulted in a more frequent incidence of disease outbreaks often leading to higher morbidity and mass mortalities with reduced overall production. In recent years, aquaculture has been adversely affected due to the frequent occurrence of disease outbreaks mostly due to intensified culture system for higher economic gain (Walker and Winton, 2010).

    Occurrence of different fish microbial and parasitic diseases in India (Nayak et al., 2007; Sahoo et al., 2013) and other Asian countries (Bondad-Reantaso et al., 2005; Faruk et al., 2004) has promoted the use of aqua medicines to control production as growth loss in fish (Ali et al., 2014; Burridge et al., 2010; Chowdhury et al., 2012; Costello et al., 2001; Joshua et al., 2002; Pathak et al., 2000). Various USFDA approved drugs to be applied in aquaculture are listed in Table 1 and 2 along with their recommended dosage. Along with their significant role in fish health management, aquaculture drugs and chemicals are also used in various other aquaculture activities like pond preparation, soil and water management, natural aquatic productivity enhancement, feed additives and growth (Plumb 1992; Subasinghe et al., 1996; Gesamp, 1997; Alam et al., 2015). Drugs and chemicals used in grow-out farms and hatchery operations in India can be classified into the broad categories as water/soil treatment products, disinfectants, piscicides, herbicides, therapeutants, anesthetics, feed additives, growth promoters, vaccines, and probiotics. List of commercially available drugs and chemicals with their recommended dosage and trade names are given in Table 3.

    i.Water and Soil Treatment Products

    Water and soil treatment is the prerequisite for the pond preparation. Many chemicals are being used in aquaculture ponds/hatcheries for mineralizing excess organic matters, adjusting pH, and for disinfection. Traditionally, lime in the form of lime stone (CaCO3), slaked lime (Ca(OH)2) or un-slaked lime (CaO) were used for preparing pond. However, for maximum output several innovative compositions have been developed to maximize production. Some of the innovative compositions are Eiffer, Geotox, Zeolite, Zeocare, Lime, Bio Aqua, Aquanone, Zeo prime etc., are used for the pond preparation and water quality management. Disinfection and sterilisation of dried ponds are also done using active iodine or potassium permanganate (KMnO4). Commercially available zeolite and porous aluminium silicate are applied along with lime for re-activating the soil to stabilize algal growth and to absorb fouling materials.

    ii. Disinfectants used in Aquaculture

    Disinfectants are used extensively worldwide in different aspects of aquaculture. The greatest quantities are used in intensive culture, particularly in finfish and grow-out facilities. They are used in site and equipment preparation, to maintain hygiene throughout the production cycle and, in some cases, to treat disease. Bleaching, Beize, Aquakleen, BKC, EDTA, Efinol, Formalin, Water clear are the aquamedicines used for disinfecting pond as well as to treat diseased conditions. Formalin is also used to control the protozoan disease. Beize is a product can be used during the ulcerative disease, bacterial infection, fungal attack as well as in any other kind of infectious conditions. Most commonly used agent for controlling the bacterial disease is BKC (Benzal Konium Chloride) and to increase stress resistance, Efinol can also be used. Sodium hypochlorite, BKC, calcium carbide and Na-EDTA are some commonly used disinfectants. These are applied mostly in hatcheries and also in grow-out ponds, to a limited extent.

    iii. Piscicides and Herbicides

    In aquaculture practices, eradication of unwanted predatory fishes is a common pre-stocking management step. Most frequently used fish piscicides are mahua oil cake, tea seed cake, other plant derivatives and anhydrous ammonium substances.

    Aquatic weeds are of common occurrence in fishponds in the country and are undesirable, as they pose serious problems by upsetting the oxygen balance and removing nutrients from the aquatic systems. Various pesticides like algicides and herbicides are being used in ponds to reduce/remove  the number of unwanted aquatic plants from the pond.. Larger aquatic plants create dense communities that interfere with feeding and harvest. Herbicides used to control aquatic weeds are 2,4-D, Dalapon, Paraquat, Diuron, and many others ammonia derivatives.

    iv. Commonly Applied Therapeutants

    Intensification has resulted in an incidence of several bacterial diseases in aquaculture leading to the increased application of antimicrobials agents (Defoirdt et al., 2011, 2007). Antibiotics are frequently administered for short periods of time as therapeutics to groups of infected fish. Food and Drug Administration (FDA) has approved florfenicol, sulfamerazine, oxytetracycline dihydrate, oxytetracycline hydrochloride, as well as a drug combination of sulfadimethoxine and ormetoprim for use in aquaculture as long as the fish contains less than a mandated maximum residue limit. Various vaccines have also been developed and commercialised for use in aquaculture against various bacterial and viral pathogens.

    Parasitic infestations are widely distributed in freshwater fish which include single celled protozoan and multi-cellular trematodes, crus­taceans and arthropods (Woo, 2006). The drugs and chemicals frequently used in aquaculture to control parasitic infestations included Nuvan, Butox Vet, Cliner, Ectodel (2.8%), Emamectin Benzoate (EB), Hitek Powder, Paracure-IV etc. Among these Butox Vet and Cliner has comparatively higher market demand than other products. However, there has been no official recommendation for use of such products in aquaculture, although many such products have been permitted for use in veterinary animals.

    v. Anaesthetics Used for Fish

    Anaesthetics are chemical or physical agents used to calm animals and cause them to lose their mobility, equilibrium, consciousness progressively, and finally their reflex action. In fisheries and aquaculture, anaesthetics are helpful for reducing the stress caused by handling and transport. The use of anaesthetics in aquaculture in India is particularly in the long distance transport of brood-stock and fish seed. The most common anesthetic drugs used in fish are MS-222 (Tricaine), benzocaine, isoeugenol, metomidate, 2-phenoxyethanol, and quinaldine (Summerfelt and Smith, 1990; Ross and Ross, 2008; Neiffer and Stamper, 2009; Ackerman et al., 2011).

    vi. Feed Additives

    Advancement in aquaculture practices causes major shift from using supplementary fish feeds comprising of agricultural by-products to nutritionally balanced species specific complete feeds. This balanced feed contains various additives in the form of pigments, vitamins, chemo-attractants, and preservatives, like mould inhibitors and antioxidants. Some of the additives are used for enhancing the digestibility as well as to reduce the anti-nutrient effects such as acidifiers, exogenous enzymes Other additives, such as probiotics, prebiotics, phytogenics, and immune-stimulants target the improvement of intestinal health, stress and disease resistance. Aquakure and Immstim are used as probiotic and immunostimulant, respectively for better harvest by the farmers of India.

    vii. Growth Promoters for Fish

    Various growth promoters are used by the farmers of India are Megavit Aqua, Aqua Boost, Aqua Savor, Vitamin premix, Fibosoel, Grow fast, Orgavit auqa, AQGrow-G, Fish vita plus, AQ Grow-L, Nature Aqua GP, Vitamix, F Aqua, ACmix, Min all, Immstim and many more. Aqua boost contains immune stimulant which enhances non-specific immunity in fish. However, Immstim is one of the immunostimulant developed by the Central Institute of Brackish Water, ICAR, Govt. of India and have shown significant increase in the production at farmers filed.

    viii. Probiotics used in Fish Farming

    The common probiotics used in pond management are live bacterial culture (non-pathogenic organisms) and fermentation products rich in extracellular. Benefits of using probiotics in aquaculture ponds include enhanced decomposition of organic matter; reduction in nitrogen and phosphorus concentrations; better algal growth; greater availability of dissolved oxygen; control of ammonia, nitrite, and hydrogen sulfide; lower incidence of disease and greater survival and fish production. However, studies have shown very few positive benefits resulting from the addition of probiotics (Boyd and Gross, 1998; Queiroz and Boyd, 1998; Queiroz et al., 1998). The probiotic contains a mainly different concentration of beneficial bacteria which include Bacillius sp., Rodobacter sp., Rodococcus sp., Streptococcus faecalis, etc. No food and environment safety hazards are thought to be presented by addition of probiotics to aquaculture ponds. Progut, Aquakure like product are very much beneficial for the gut as well as environment health, respectively.

    2. Mode of Drugs administration in Aquaculture

    Water medication and medicated feed are the two most common routes for the administration of antimicrobials in aquaculture. Medicating fish through the water is done when the fish biomass is small, such as with fry, and when adequate oral therapy is impractical. Water medication is simple and it can be simply broadcasted over the pond based on the volume of water present in the tank. Generally, low molecular weight aquamedicines  are recommended for water medication as they can be distributed thoroughly throughout the water. Drugs are absorbed by the fish through the gills epithelia, skin and mucosa and kill pathogens.

    Medicated feeds are prepared by the addition of a small amount of the aquamedicines to a homogenised and extruded diet, or sometimes the drug may be sprayed over the feed or top-coated onto the feed. The advantage of in-feed medication over water medication is the reduced wastefulness of the expensive medicines. It also reduces undesirable exposure of the environment and other fish to the drug. This is a standard method to treat a large population of diseased fish. The only limitation of this method is that the fish under treatment must be feeding actively.

    Gavage method is used in experimental work as oral administration because the precise dose is known. In this method, stomach tube is attached to a syringe containing a drug, and the drug is pumped into the stomach of the affected fish. However, fish need to be anaesthetised before administration of the drug. The applicability of the method is less in the aquaculture industry because it is labour intensive and stressful for the fish.

    Injection methods are used extensively for vaccine administration and treating a limited number of fish or valuable fish, but they are labour intensive. The intramuscular, intra-peritoneal, and dorso-median sinus injections are common routes of injection for fish.

    3. Problems Associated in Use of Aquaculture drugs

    Various problems were recognized linked with the application of aquaculture drugs which included lack of proper knowledge regarding the use of chemicals, lack of knowledge of the method of application of chemicals and antibiotics, indiscriminate use of drugs, lack of knowledge about the residual effect and expiry date and lack of diagnostic facilities for proper disease diagnosis. Farmers usually do not maintain the recommended dose. Sometimes farmers apply a higher dose of drugs and chemicals than the recommended dose. This higher dose cannot be tolerated by other organisms which can result in serious biodiversity loss of aquatic organisms.

    4. Conclusion

    Considering the present senario, it can be said that with the further development of the aquaculture industry, particularly in the intensified system, the applications of chemicals would be increased. The present article described the different types of aquaculture drugs which are used for fish growth and health management by the fish farmers. However, researchers and policy makers should work together to address the issues of drugs use and abuse in aquaculture with the view to nullify their negative impacts in the environment and human health. Therefore, both the government and nongovernment organizations should take the initiative for a better understanding of chemical and drug use in aquaculture management.

    Table 1. FDA Approved Aquaculture Drugs (permitted for application in fisheries and aquaculture) (US FDA, 2017)

    Sl.No.

    Drug

    Commercial Name

    Usage

    Approved Species

    1.                   

    Chorionic gonadotropin

    Chorulon®

    For improving spawning function in male and female brood finfish

    Brood finfish

    2.                   

    Formalin

    Formaldehyde solution

    For the control of Protozoa and Mono­genetic Tremetodes, and on the eggs of Salmon, Trout and Pike (esocids) for control of Fungi of the family Sapro­legniacea

    Finfish and their eggs, Penaeid shrimp

    Salmon, Trout, Catfish and Bluegill

    3.                   

    Florfenicol

    Aquaflor® Type A

    For the control of mortality due to en­teric septicemia of catfish. The toler­ance for florfenicol amine (the marker residue) in muscle (the target tissue) is 1 ppm.

    Channel catfish

    salmonids

    4.                   

    Tricaine methanesulfonate

    Tricaine-S

    MS-222

    It may not be used within 21 days of harvesting fish for food. The drug should be limited to hatchery or labo­ratory use.

    Ictaluridae (catfish), Salmonidae, Esocidae and Percidae

    5.                   

    Oxytetracycline dihydrate

    Terramycin® 200

    For feed use. In Salmonids,

    21 days; Catfish, 21 days; Lobster, 30 days. Oxytetracy­cline tolerance in the flesh is 2.0 ppm

    Catfish, Salmonids, Lobster

    6.                   

    Oxytetracycline hydrochloride

    Oxymarine™ ,

    Terramycin 343, Phennoxy 343, Tetroxy Aquatic

    For feed use. In Salmonids,

    21 days; Catfish, 21 days; Lobster, 30 days. Tolerance in the flesh is 2.0 ppm

    Finfish fry and fingerlings

    7.                   

    Sulfadimethoxine/Ormetoprim

    Romet-30®

    Withdrawal times are: Salmonids, 42 days; catfish, 3 days

    Catfish, salmonids

    8.                   

    Sulfamerazine

    Sulfamerazine

    It may not be used within

    21 days of harvest.

    Note: This product is currently not marketed

    Trout (rainbow, brook, brown)

    9.                   

    Chloramine-T

    Halamid® Aqua

    -

    Freshwater-reared salmonids,

    Freshwater-reared warm water finfish

    10.               

    Hydrogen peroxide

     

    -

    -

    Fin fish eggs,

    Salmonids,

    Cold freshwater reared finfish

     

    Table 2. FDA low regulatory priority aquaculture drugs permitted for application in fisheries and aquaculture (US FDA, 2017).

    Sl. No

    Name of the Drug

    Recommendations

    1.       

    Acetic acid

    1000 to 2000 ppm dip for 1 to 10 minutes as a parasiticide for fish

    2.       

    Calcium chloride

    Used to increase water calcium concentration to insure proper egg hardening.

    3.       

    CaCO3

    Used up to 150 ppm indefinitely to increase the hardness of water for holding and transporting fish to enable fish to maintain osmotic balance

    4.       

    Calcium oxide

    Used as an external protozoacide for fingerlings to adult fish at a concentration of 2000 mg l-1 for 5 seconds

    5.       

    Carbon dioxide Gas

    Anesthetic purposes in cold, cool, and warm water fish

    6.       

    Fuller’s Earth

    To reduce the adhesiveness of fish eggs to improve hatchability

    7.       

    Garlic (Whole Form)

    Used for control of helminth and sea lice infestations of marine salmonids at all life stages

    8.       

    Hydrogen peroxide

    Used at 250-500 mg l-1 to control fungi on all species and life states of fish, including eggs

    9.       

    Ice

    Used to reduce metabolic rate of fish during transport

    10.   

    Magnesium sulfate

    Used to treat external monogenic trematode infestations and external crustacean infestations in fish at all life stages. Fish are immersed in a 30,000 mg, MgSO4 l-1 and 7000 mg NaCl l-1 solutions for 5 to 10 minutes

    11.   

    Onion (Whole Form)

    Used to treat external crustacean parasites, and to deter sea lice from infesting external surface of salmonids at all life stages

    12.   

    Papain

    Used in a 0.2% solution to remove the gelatinous matrix of fish egg masses to improve hatchability and decrease the incidence of disease

    13.   

    Potassium chloride

    Used as an aid in osmoregulation; Relieves stress and prevents shock. Dosages used would be those necessary to increase chloride ion concentration to 10-2000 mg l-1

    14.   

    Povidone Iodine

    Used in a 100 mg l-1 solution for 10 minutes as an egg surface disinfectant during and after water hardening

    15.   

    Sodium bicarbonate

    Used at 142 to 642 mg l-1 for 5 minutes as a means of introducing carbon dioxide into the water to anesthetize fish

    16.   

    Sodium chloride

    Used in a 0.5% to 1.0% solution for an indefinite period as an osmoregulatory aid for the relief of stress and prevention of shock; and 3% solution for 10 to 30 minutes as a parasitide

     

    Table 3. List of chemicals used in aquaculture along with their trade names and recommended dosage

    Sl. No.

    Trade Name

    Active Ingredients

    Dosage

    Manufacturer

    1.       

    Eiffer

    SiO2, Al2O3, Fe2O3, CaO, MgO, Na2O, K2O

    15-20kg/acre

    Rajshree

    2.       

    AquaKureF

    Water Probiotic

    1kg/acre

    Rajshree

    3.       

    Beize

    Disinfectant

    1-2 litre/acre

    Rajshree

    4.       

    MineAll

    Minerals

    1-2kg/m3

    Rajshree

    5.       

    IMMSTIM

    Immunostimulant

    5-10ml/kg feed

    Rajshree

    6.       

    Super Zeolite

    SiO2, Al2O3, Fe2O3, CaO, MgO, LoI, K2O

    20-30kg/acre

    Avon Animal Health

    7.       

    Aquanone

    Rotenone

    5-7kg/acre

    Square Pharmaceuticals Ltd.

    8.       

    Aqua Lime

    CaCO3, Ca(OH)2

    1–2 kg/dec

    ACI Animal Health

    9.       

    BKC

    Benzal konium chloride

    Spread with water, 0.5 ppm

    Chemical seller

    10.   

    Formalin

    38% Formaldehyde

    1–3 ppm

    Chemical Seller

    11.   

    Lenocide

    Ankul benzyl dimethyl ammonium chloride + poly-2 deoxy-2 amino glucose

    500–1000 ml/acre

    Nature care

    12.   

    Aquakleen

    Tetradesail Tri-methyl Amonium bromid, BKC

    0.5-1 L/acre

    Square pharmaceuticals Ltd.

    13.   

    Oxymax

    H2O2 10%

    250-500 gm/acre (1 m deep water body)

    Eon animal health products Ltd.

    14.   

    Oxy flow

    H2O2 10%

    General dose 250–350 gm/acre. In case of high deficiency 500 gm/acre in the same water body

    Novartis Pharmaceuticals Ltd.

    15.   

    Registrol

    Betain, Calcium, P, Vit-C

    5-10ml/kg feed

    Square pharmaceuticals Ltd.

    16.   

    Oxysentin 20%

    Oxytetracycline HCL BP

    50–100 gm/100 kg feed, 5–7 days (for treatment)

    Novartis pharmaceuticals ltd.

    17.   

    Megavit Aqua

    Vitamin, mineral and amino acid supplement

    100 g/100 kg feed

    Novartis pharmaceuticals ltd.

    18.   

    C-150

    Coated Vit-C

    5 g/kg feed

    CP Aquaculture

    19.   

    Super Biotic

    Bacillus sp.

    1–2 kg/ acre

    CP Aquaculture

    20.   

    Super PS

    Rodobacter sp. Rodococcus sp.

    4–6 L/acre

    CP Aquaculture

    21.   

    Aqua boost

    An organic acid, ß-glucan

    500 g/mt feed

    Novartis pharmaceuticals ltd.

    22.   

    Pond D tox

    Pracoccus pantotrophus

    4 ppm

    Fish tech.(BD) Co. Ltd.

     

    Further Readings

    Ackerman, P.A., Morgan, J.D., Iwama, G.K. (2011). Anesthetics. CCAC guidelines on: The care and use of fish in research, teaching and testing, Canadian Council on Animal Care, Ottawa, CA.

    Alam, C.A., Uddin, M.S., Vaumi, S., Abdulla, A.A. (2015) Aqua drugs and chemicals used in aquaculture of Zakigonj upazilla, Sylhet. Asian Journal of Medical and Biological Research 1: 336-349.

    Ali, M.M., Rahman, M.A., Hossain, M.B. and Rahman, M.Z. (2014) Aquaculture Drugs Used for Fish and Shellfish Health Management in the Southwestern Bangladesh. Asian Journal of Biological Sciences, 7: 225-232.

    Bondad-Reantaso, M.G., Subasinghe, R.P., Arthur, J.R., Ogawa, K., Chinabut, S., et al. (2005) Disease and health management in Asian aquaculture. Vet Parasitol 132: 249-272.

    Boyd, C.E., Gross, A. (1998). Use of probiotics for improving soil and water quality in aquaculture ponds. In: Flegel, T.W. (Ed.), Advances in Shrimp Biotechnology. Proceedings to the Special Session on Shrimp Biotechnology, 5th Asian Fisheries Forum, 11-14 November 1998, Chiengmai, Thailand. The National Center for Genetic Engineering and Biotechnology, Bangkok, Thailand, pp. 101–106.

    Burridge, L., Weis, J.S., Cabello, F., Pizarro, J., Bostick, K. (2010) Chemical use in salmon aquaculture: A review of current practices and possible environmental effects. Aquaculture 306: 7-23.

    Chowdhury, A.K.J., Saha, D., Hossain, M.B., Shamsuddin, M., Minar, M.H. (2012). Chemicals Used in Freshwater Aquaculture with Special Emphasis to Fish Health Management of Noakhali, Bangladesh. African Journal of Basic & Applied Sciences, 4: 110-114.

    Costello, B.M.J., Grant, A., Davies, I.M., Cecchini, S., Papoutsoglou, S, et al. (2001) The control of chemicals used in aquaculture. European Journal of Applied Ichthyology 17: 173-180.

    DADF (2016). Guidelines - Central Sector Scheme on Blue Revolution: Integrated Development and Management of Fisheries. Department of Animal Husbandry, Dairying & Fisheries, Ministry of Agriculture and Farmers Welfare, Government of India, India.

    Defoirdt, T. et al. (2007). Alternatives to antibiotics to control bacterial infections: luminescent vibriosis in aquaculture as an example, In: Trends in biotechnology. 25 (10), pp. 472-9.

    Defoirdt, T. Sorgeloos, P. and Bossier, P. (2011). Alternatives to antibiotics for the control of bacterial disease in aquaculture, In: Current opinion in microbiology. 14 (3), pp. 251-8.

     FAO (2016). Opportunities and challenges. The State of World Fisheries and Aquaculture. Food and Agriculture Organization of the United Nations, Rome, Italy.

    Faruk, M.A.R., Alam, M.J., Sarker, M.M.R. and Kabir, M.B. (2004) Status of fish disease and health management practices in rural freshwater aquaculture of Bangladesh. Pakistan Journal of Biological Science 7: 2092-2098.

    Gesamp (1997). Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection. Pullin RSV, Rosenthal H, Maclean JH (eds.). Towards safe and effective use of chemicals in coastal aquaculture. Geneva, Switzerland.

    Joshua, K., Sujathat, A., Ramana, L.V., Carolin, E., Supraba, V., et al. (2002) Use of various chemicals in shrimp hatcheries and its sustainability in hatchery technology. Paper presented in National Workshop on Aquaculture Drugs, January 18-20, 2002. CFDDM, Cochin University of Science and Technology, Cochin, Kerala, India.

    Murray, A.G. and Peeler, E.J. (2005). A framework for understanding the potential for emerging diseases in aquaculture. Prev Vet Med, 67:223-235.

    Nayak, S.K., Swain, P. And Mukherjee, S.C. (2007) Effect of dietary supplementation of probiotic and vitamin C on the immune response of Indian major carp, Labeo rohita (Ham.). Fish Shellfish Immunol 23: 892-896.

    Neiffer, D.L. and Stamper, M.A. (2009). Fish sedation, anesthesia, analgesia, and euthanasia: considerations, methods, and types of drugs. Ilar J,  50:343-360.

    Pathak, S.C., Ghosh, S.K., Palanisamy, K. (2000) The use of chemicals in aquaculture in India. Southeast Asian Fisheries Development Cente, Iloilo, Philippines.

    Plumb, J.A. (1992) Disease Control in Aquaculture. In: Shariff IM, Subasinghe RP, Arthur JR (eds.). Disease in Asian Aquaculture I. Fish Health Section, Asian Fisheries Society, Manila, Philippine.

    Press Information Bureau (2017). Blue Revolution, Ministry of Agriculture, Government of India, India.

    Queiroz, J.F., Boyd, C.E. (1998). Effects of a bacterial inoculum in channel catfish ponds. J. World Aquac. Soc. 29: 67–73.

    Queiroz, J.F., Boyd, C.E., Gross, A. (1998). Evaluation of a bio-organic catalyst in channel catfish, Ictalurus punctatus, ponds. J. Appl. Aquac. 8: 49–61.

    Ross, L.G. and Ross, B. (2008). Anaesthetic and Sedative Techniques for Aquatic Animals. Oxford, UK, Blackwell Publishing, p 222.

    Sahoo, P.K., Mohanty, J., Garnayak, J.S.K., Mohanty, B.R., Kar, B., et al. (2013) Estimation of loss due to argulosis in carp culture ponds in India. Indian Journal of Fisheries.

    Subasinghe, R.P., Barg, U., Tacon, A. (1996). Chemicals in Asian aquaculture: need, usage, issues and challenges. Arthur JR, Lavilla-Pitogo CR, Subasinghe RP (eds.). Use of Chemicals in Aquaculture in Asia. Southeast Asian Fisheries Development Center, Aquaculture Dept, Asia, Philippines.

    Summerfelt, R.C. and Smith, L.S. (1990). Anaesthesia and surgery and related techniques, in Schreck CB, Moyle PB (eds): Meth ods for Fish Biology. Bethesda, MD, American Fisheries Society, pp 213-272.

    US Food and Drug Administration (2017). Approved Aquaculture Drugs. US Food and Drug Administration, Maryland, USA.

    Walker, P.J. and Winton, J.R. (2010) Emerging viral diseases of fish and shrimp. Vet Res 41: 51.

    Woo, P.T.K. (2006) Fish Diseases and Disorders, (2nd edn). Protozoan and Metazoan Infections. Cambridge, USA.


    Share this post