Fish Nutrition
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Fish Nutrition

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Fish Nutrition Fish Nutrition Presentation Transcript

  • Aquaculture Nutrition
  • Feed Conversion Ratio
    • The measure of an animals efficiency at converting pounds of food to pounds of body mass.
    • Examples:
      • Cows 8:1, 8 lbs of food for 1 lb meat gain
      • Pigs 4:1
      • Chickens 2:1
      • Fish
        • Tilapia 1.7:1
        • Atlantic Salmon 1.2:1
  • Fish Conversion Efficiency
    • The basic principle in feeding is that the fish should be fed exactly to satiation.
    • Reasons for efficiency
      • the biology of the fish,
      • the way the fish live and
      • the high nutrient concentration of fish feed.
  • Nutrition
    • Fish have a low body maintenance requirement.
      • Fish are cold-blooded:
      • Floating in the water consumes less energy than standing and walking on legs.
    • Fish feeds are also more concentrated than those for pigs or cattle, since they do not need ‘filler’ ingredients such as fiber.
    • Fish use oils and fats as their prime energy source - more concentrated than the carbohydrates needed by land-living animals.
    • Most fish are carnivorous while most farmed land animals are basically herbivorous
  • Nutrition
    • Protein
      • Balanced mix of amino acids builds muscle
    • Fat
      • Provides dense energy for metabolism
      • Oxidizes rapidly – becomes rancid
    • Carbohydrate
      • Fish can only digest simple sugars
    • Vitamins & Minerals
      • Included in mixed rations
  • Food Storage
    • Keep cool – slows oxidation
    • Keep dry – prevent mold growth
      • Mold produce mycotoxins
    • Keep covered
  • Water quality elements
    • Oxygen
    • Temperature
    • Sunlight
    • pH
    • Alkalinity
    • Hardness
    • Ammonia
    • Nitrite
  • Oxygen
    • Minimum: 4 ppm ,
    • Saturated is better. 10ppm at 25 °F
    • More air can be trapped in cold water than hot.
    • In ponds,
      • O 2 ↑ during the day
      • O 2 ↓ during the night and on cloudy days
      • O 2 can become stratified.
  • pH
    • Scale of 1 – 14, 7 is neutral
    • Preferred range 6 – 9
    • CO 2 from respiration lowers the pH ( ↑acidity)
    • Photosynthesis removes C O 2 from the pond and makes the pH higher (more basic)
    • Ammonia is more toxic at high pH levels
    • Pond water is more acidic in the morning and basic in the afternoon
  • Alkalinity/Hardness
    • Buffering capacity: ability to resist changes in pH
    • Comes from dissolved limestone
    • 20 ppm CaCO 3 acceptable, 100 ppm or more is ideal.
    • Add lime to adjust
  • Ammonia
    • Excess nitrogen from fish metabolism & waste
    • Consumed by algae (ponds) and bacteria (tanks)
    • Toxic to fish especially at high pH level
    • Closely monitor pH.
      • More Adjustable
    • If level gets too high, ↓ density of fish and feeding levels
    • Level should be less than 2mg/L (ppm)
  • Salinity
    • Salinity – measure of salt in water in ppt (multiply by 1000 for ppm)
    • Our aquaculture tanks are ~ 1.5 ppt
    • Fresh water is less than 0.5
    • Brackish water is 0.5 to 17 (Estuaries)
    • Ocean water averages 35
  • TDS - Total Dissolved Solids
    • Related to salinity
    • Ca, Na, Mg, Cl ions in water necessary for homeostasis
    • Desired level: 1500 -1900 ppm
      • 3 - 3.8 ms/cm
    • Convert by multiplying EC (electric conductivity, mS/cm) by 500 to get ppm
  • Today
    • Water tests
    • Tomorrow –
      • Aquaculture quiz
      • Start shop safety