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Fish Health Management Lab 1: Water Quality

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Poor water quality causes more losses in aquaculture than any ... pH increases toxicity Nitrite Brown blood disease ... Design Fish Health Management ... – PowerPoint PPT presentation

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Title: Fish Health Management Lab 1: Water Quality


1
Fish Health Management Lab 1 Water Quality
  • January 25th, 2010
  • David Burbank
  • burb2155_at_vandals.uidaho.edu

2
Aquatic Environment
  • Water quality is one of the most important
    factors to maintain fish health.
  • Poor water quality causes more losses in
    aquaculture than any other problem.
  • Factors that influence water quality/quantity in
    aquaculture
  • Feed rates
  • Feed types
  • Flow rates
  • Tanks/containers (flow dynamics)
  • Temperature

3
Water quality testing
  • Daily or weekly tests
  • Basic tests
  • Relatively quick and inexpensive
  • i.e. Temp, DO, Cl, ect
  • Semi-annual or annual
  • Extensive more precise
  • Expensive and time consuming
  • i.e. Heavy metals
  • Are catered to specific
  • concerns for the facility

4
Daily or Weekly
  • Dissolved oxygen
  • Temperature
  • Nitrogen compounds
  • Ammonia (NH3)
  • Nitrite (NO2-)
  • Nitrate (NO3-)
  • pH
  • Alkalinity
  • Carbon Dioxide
  • Hardness
  • Hydrogen sulfide
  • Total suspended solids
  • Chlorine

5
Dissolved Oxygen
  • Inadequate DO can cause mortality and contribute
    to chronic stress and ill health
  • Solubility
  • dependent on
  • Temperature
  • Elevation
  • Salinity
  • Safe levels
  • greater than 5 mg/L for salmonids
  • greater than 3 mg/L for warm water fish

Mg/L
6
Dissolved Oxygen
  • Uptake influenced by condition of gills
  • Partial pressures are important
  • If lamellae are not healthy, the demand may not
    be met.
  • Water DO levels below saturation can adequately
    provide saturation of hemoglobin, however a
    safety margin should be maintained.

7
Oxygen Requirements
  • Dependent on Temperature
  • Metabolic increases with temperature
  • Dependent on demands of organism
  • Energetic demands swimming, digestion, etc.
  • Energetic costs of ventilation
  • Efficiency of uptake varies in species

8
Temperature
  • Effects
  • metabolic rate doubles for every 8C increase
  • Influences spawning
  • Influences growth
  • Influences pathogens
  • Fish Categories
  • warmwater
  • coolwater
  • coldwater

9
Nitrogen Compounds
  • Types
  • dissolved gas
  • ammonia
  • ionized (NH4)
  • un-ionized (NH3)
  • nitrite (NO2-)
  • nitrate (NO3-)

10
Nitrification
  • Requires 3 moles oxygen to convert one mole of
    ammonia to nitrate
  • Nitrification is an acidifying reaction

11
Ammonia
  • Ammonia (NH3) results from the breakdown of fish
    feed, and waste
  • Two forms
  • ionized (NH4)
  • unionized (NH3)
  • Unionized ammonia concentration is a function of
    pH and temperature
  • Chronic exposure (unionized form)
  • 0.06 mg/L is toxic to warm water fish
  • 0.03 mg/L is toxic to salmonids

12
Nitrite
  • Nitrite (NO2-) is the intermediate product in the
    breakdown of ammonia to nitrate (nitrification)
  • Nitrite levels greater than 0.5 to 0.6 mg/L or 10
    times higher than the toxic threshold for
    unionized ammonia are toxic to fish
  • Catfish will tolerate 13 mg/L
  • Salmonids will tolerate lt0.3 mg/L
  • Decreasing pH increases toxicity

13
Nitrite
  • Brown blood disease (Methemoglobinemia)
  • Iron in the heme molecule is reduced and cannot
    transport oxygen
  • Blood appears dark in color and fish cannot meet
    oxygen demands
  • Treatment
  • Salt
  • Chloride ions out-compete nitrite
  • Recommend 101 ratio
  • Hypertrophy and hyperplasia in the gill lamellae
  • Lesions/hemorrhaging in thymus

14
Nitrate
  • Nitrate (NO3-) is the final breakdown product in
    the oxidation of ammonia
  • Nitrate is relatively nontoxic to fish at
    concentrations up to 3.0 mg/L
  • May be problem in embryo development

15
Nitrogen thresholds for salmonids
16
pH
  • Measure of the hydrogen ion concentration
  • 1-14 scale
  • less than 7 acidic
  • greater than 7 basic
  • Safe range
  • generally 6.5-9.0
  • (species variable)

17
Carbon Dioxide
CH2O (food) O2 ? CO2 H2O
  • Sources
  • bi-product of respiration of fish and
    phytoplankton
  • wells
  • carboniferous rock
  • (i.e. black shale, coal)
  • Removal
  • intense aeration
  • buffers
  • calcium carbonate
  • sodium bicarbonate

18
Alkalinity
  • Alkalinity is the capacity of water to buffer
    against wide pH swings
  • Acceptable range 20-300 mg/L

Bicarbonate CO2 H2O ? H HCO3-
Carbonate HCO3- ? H CO3-
Effects of calcite lime
CaCO3 CO2 H2O ? Ca2 2HCO3-
Dolomite CaMg(CO3)2 yields 4HCO3-
19
Hardness
  • Hardness is the measure of divalent cations
  • Calcium
  • Magnesium
  • Suggest gt 50 ppm
  • Hardness is used as an indicator of alkalinity
    but hardness is not a measure of alkalinity
  • Magnesium or calcium sulfate increases hardness
    but has no affect on alkalinity
  • If hardness is deficient then fish grow poorly

20
Hydrogen Sulfide
  • Source
  • Well water
  • Ponds
  • shift from aerobic to anaerobic breakdown of
    wastes
  • Can develop under net pens
  • Extremely toxic to fish
  • Removal
  • Intense aeration
  • Draining and drying of pond

21
Total Solids
  • Types
  • suspended
  • settleable
  • Sources
  • runoff
  • uneaten food
  • feces
  • Safe levels
  • less than 1,000 mg/L
  • Removal
  • filtration
  • settling chambers

22
Suspended Solids
  • Potential problems
  • Source of irritation/nutrients on gills
  • Inflammation and damage to gills
  • Bacterial or fungal colonization on gill surface
  • Reduce oxygen transport
  • 80 - 100 ppm TSS reasonable for salmonids

23
Chlorine
  • Chlorine, (sodium hypochlorite or calcium
    hypochlorite) reacts with water to form strong
    acid
  • Cl2 H20 H0Cl H Cl -


24
Chlorine
  • Disinfectant
  • municipal water
  • cleaning tanks and equipment
  • Safe levels
  • less than 0.03 mg/L
  • Removal
  • intense aeration
  • sodium thiosulfate
  • 1 mg/L for every mg/L chlorine
  • Sunlight
  • Filtration (carbon filters)

25
Chlorine toxicity
  • Acid is more toxic than hypochlorite ion
  • Destroys epidermal surfaces (especially gills)
  • Toxicity depends on temp, DO, free chlorine
    present, presence other pollutants
  • Residual chlorine (free plus chloramine) 0.2 -
    0.3 ppm kills fish rapidly
  • Chlorine and nitrogenous organics chloramines
    that are very toxic

26
Heavy Metal Contaminants
  • Heavy metals - Cd, Cu, Zn, Hg, must be all lt .1
    mg/L.
  • In aquaculture watch out for plumbing systems
    (copper, zinc alloys) PVC is preferred choice.
  • Soft water makes a difference in toxicity of
    metals

27
Dissolved Gasses
  • Problem gasses
  • nitrogen
  • maintain less than 110
  • Problem sources
  • wells and springs
  • leaky pipes
  • Dams

28
Characteristics of gas bubble disease
  • Bubbles under skin
  • fins
  • tail
  • mouth
  • gas emboli in vascular system death
  • similar to bends or decompression sickness
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