Fish Health Management Lab 1: Water Quality

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Fish Health ManagementLab 1 Water Quality

• January 25th, 2010
• David Burbank
• burb2155_at_vandals.uidaho.edu

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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

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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

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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

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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
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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.

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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

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Temperature

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

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Nitrogen Compounds

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

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Nitrification

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

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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

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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

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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

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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

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Nitrogen thresholds for salmonids
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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)

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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

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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-
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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

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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

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Total Solids

• Types
• suspended
• settleable
• Sources
• runoff
• uneaten food
• feces

• Safe levels
• less than 1,000 mg/L
• Removal
• filtration
• settling chambers

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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

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Chlorine

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

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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)

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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

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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

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Dissolved Gasses

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

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Characteristics of gas bubble disease

• Bubbles under skin
• fins
• tail
• mouth
• gas emboli in vascular system death
• similar to bends or decompression sickness