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Aquaculture Systems Water Exchanges Dilutes waste products, corrects pH pH Organics Nitrite Nitrate Ammonia Water Change TIME.

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Presentation on theme: "Aquaculture Systems Water Exchanges Dilutes waste products, corrects pH pH Organics Nitrite Nitrate Ammonia Water Change TIME."— Presentation transcript:

1 Aquaculture Systems Water Exchanges Dilutes waste products, corrects pH pH Organics Nitrite Nitrate Ammonia Water Change TIME

2 Water Quality Management Raceways: water flow = carrying capacity Ponds: pond depth and photosynthesis dissolved oxygen ability of pond to conduct nitrogen cycle to detoxify N-compounds Cages: total carrying capacity = that of the body of water had the cages not been present

3 Water Quality Management (cont.) Recirculation Systems: Water must be managed/monitored carefully DO: provided mechanically Detoxification of N-compounds: performed by large biofilters Need to carefully monitor the performance of these life support systems

4 Water Quality Management (cont.) Recirculation Systems: Need to carefully monitor the performance of these life support systems Computerized monitoring: My opinion – Computers are OK for record keeping, but you need to take corrective action in 5 minutes or the system will go down. You have to have a person at a recirculation production system 24/7.

5 Fish Physiology Basics The Fish as a Cold-blooded Animal Physiology Oxygen Requirement Growth Food Requirements Immune System Interactions between host and pathogen

6 Fish Physiology Basics Osmotic Regulation Importance of the skin as an osmotic barrier Importance of the kidneys in maintenance of osmotic balance

7 Fish Physiology Basics Osmotic Regulation.. Freshwater Saltwater Osmotic Pressure Excrete high volume of dilute urine Drinks water

8 Fish Physiology Basics Osmotic Regulation.. Freshwater Saltwater Osmotic Pressure In both freshwater and saltwater fish, the skin is an extremely important organ for maintaining proper osmotic balance. Drinks water

9 Fish Physiology Basics Gills Respiration Excretion of nitrogenous waste Ion balance Gills are vulnerable to various forms of damage

10 Fish Physiology Basics Nutrition Most of fish nutrition information is for important aquaculture species Channel catfish, trout, salmon Information on other species is lacking Know specifics for your species Use a variety of foods from reputable manufacturers; rotate manufacturers

11 Disease Diagnosis Basic Necropsy Procedure Quality of the specimen Live fish showing the signs of the disease in question “Fresh dead” – still has red color to the gills A fish with white gills has started to under post-mortem decomposition – will be of little value

12 Disease Diagnosis Shipping Specimens –See “General Fish Health Management” –NRAC Bulletin Live Iced Frozen Formalin Fixed Issues of shipment of hazardous materials

13 Disease Diagnosis Basic Necropsy Procedure –External examination Gills Fins Skin Any external lesions –Examine grossly and microscopically –Fresh material: can see living organisms

14 Disease Diagnosis Basic Necropsy Procedure –Internal Examination Disinfect External Surface Aseptically open abdomen (avoid contamination) Bacterial culture from posterior kidney and any visible lesions Specimens for viral isolation Specimens for histopathology Complete exam of internal organs

15 Disease Diagnosis Basic Necropsy Procedure –Internal Examination

16 Disease Diagnosis Basic Necropsy Procedure –Follow-up Culture, ID, antibiotic sensitivity of bacteria Culture, ID of viruses Identification of parasites Evaluation of histopathology Evaluation of case history –Many times the case history can be of paramount importance in resolving the case

17 Disease Diagnosis Case History (examples of information) Water sourceTemperature Dissolved OxygenTotal ammonia, pH NitriteHardness, Alkalinity Any new fishnew food System breakdownRapid temperature change Change in water color Source of foodHow food stored Age of food Mortality pattern: acute, chronic, recent increase etc.

18 Your “Fish Room” A Constant Environment is Important –Water temperature –Dissolved oxygen –General water quality parameters Ammonia Nitrite Nitrate Change is not good for FISH

19 Your “Fish Room” The Quality of the Fish –Captive bred fish –Wild fish –Fish health implication of Facultative vs. Obligate Pathogens

20 Your “Fish Room” Equipment –Nets –Tanks –Tank cleaning equipment Benzalkonium Chloride (50%: 1 oz/5 gal = 750 mg/L

21 Your “Fish Room” Lids on tanks –Keep fish in (fish jump) –Keep pathogens out (some fish pathogens can move via aerosols; fish tank rooms have high humidity) Transmission of pathogens via aerosols

22 Your “Fish Room” Tank Records –Water quality data – decide on the frequency of testing based on the type of system (tank, flow-through tank, static tank, pond) –Consider the density of fish –This is not a “one-size-fits-all” – But you must decide for your system

23 Your “Fish Room” Tank Census –Your ability to count number of fish vs. a good faith estimate –Daily mortality records (will help in Dx investigations) Disease TX –Records of what has been found and the management to correct/TX the problem FORMS SERVE AS AN EXCELLENT REMINDER TO DO THE TANK CHECKS

24 Your “Fish Room” Electricity –Water and Electricity don’t mix –Exercise caution –Ground-fault interrupt circuits –Back-up systems; fish depend on life-support systems that are powered by electricity

25 Your “Fish Room” Disease Management –Have SOP’s –Quantity of therapeutic compounds required to Tx systems of different sizes –Avoid mistakes when you (and the fish) are stressed

26 Disease Diagnosis General Comments –Can’t Dx over the phone –Can’t diagnose based on grossly visible signs –We need to examine a fish using a variety of Dx tools –Case history can be extremely important

27 Disease Diagnosis Exam –Work from the outside of fish to internal exam at the later stages of the exam Skin scrapings Gill clippings Fin clippings –Examine under a microscope

28 Disease Diagnosis Exam –Culture for bacteria from the posterior region of the kidneys Identification of any bacteria – various biochemical tests Determination of antibiotic sensitivity Size of zone of inhibition provides an indication of relative sensitivity to the antibiotic

29 Disease Diagnosis Viral Exam –Collect select internal organs (usually kidney, spleen, liver) –Prepare cell-free filtrate –Inoculate fish cell culture –Examine for cytopathic effects (CPE) Appropriate cell lines are not available for all species of fish for Dx of viral diseases

30 Disease Diagnosis Histopathology –Remove organs and fix in 10% neutral buffered formalin 10:1 Rule 1 cm rule Plastic New considerations with shipment of hazardous materials via commercial shippers

31 Disease Diagnosis Evaluation of all information –Parasites –Bacteria –Viruses –Non-infectious –Case history Arrive at a diagnosis –Tx –Change in management

32 A few comments on occupational health

33 Fish Health and Your Health Puncture wounds from spines Toxic fish (i.e.. Madtoms, other Ictalurids) Fish pathogens and you –Mycobacteriosis Mycobacterium marinum Mycobacterium fortuitum Mycobacterium piscium Mycobacterium sp. –Other opportunistic bacteria (for puncture wounds)

34 Mycobacteriosis “Typical” signs of disease – any combination of: hemorrhageanorectic (reduced feeding) swollen abdomen exphthalmia (“pop eye”) ulcers lethargic

35 Mycobacteriosis Striped Bass Lesions: Multifocal hemorrhagic lesions on body Lethargy Anorectic (poor feeding) On microscopic exam – gralumomas with acid-fast bacteria (Mycobacterium sp.)

36 Mycobacteriosis “Typical” internal signs of disease: “nodules” (= granulomas)

37 Mycobacteriosis Gram Stain Acid Fast Stain Histopathology

38 Mycobacteriosis Mycobacteriosis is zoonotic! Mycobacteria enter the skin through small abrasions Lesions appear as severe swelling; sometimes the lesions will ulcerate Need to work with the human medical community

39 From: New England Journal of Medicine (2004) Vol. 350;9,e8 Photo credit: C. Nguyen, M.D. Mycobacterium marinum infection

40 What Should You Do Some common sense: hand washing, handle fish carefully to avoid injury to you and the fish If you sustain an injury (spine wound, a raised ulcerated area that does not heal) Seek medical treatment

41 Questions?


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