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Best Aquaculture Practices (BAP’s)
and
Feed and Waste Management
Daniel Miller
[email protected]
Florida A&M University
Farmer to Farmer Program
Stellenbosch, South Africa
February, 2010
Upon the completion of this lesson
participants will be able to:
 List and describe 3 types of waste and 3 levels
of water treatment.
 Describe feeding methods and the factors that
influence fish feeding.
 Discuss how feed impacts water quality.
 Describe how to handle and dispose of waste.
 Calculate how much sawdust is needed to
convert fish waste into mulch.
 Describe how to reduce phosphorus in waste.
Waste Minimization in Aquaculture
is critical and economical
Choose high energy formulas for feed.
 Feed Manufacturing Process (extrusion)
 Feed handling and feeding practices.
 Design factors – for rapid concentration and
removal of solid waste
 Although waste minimization is the best first step,
it is not sufficient for regulatory agencies.
 Costlier feed can reduce the cost of production.
Feed Ingredient Options
 Know the nutritional requirements of species.
 Research indicates trout growth is reduced when
phosphorus levels < 1%.
 Work with your fish feed manufacturer.
 Choose a formula low in phytate for phosphorus
reduction.
 Choose a formula with phytase to reduce
phosphorus discharges.
Feed Management
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Keep daily feeding records for each tank.
Try to use feed within 8 to 10 weeks.
After each harvest calculate feed conversions.
Feed Conversion Ratio (FCR) should be around
1.2 lbs. feed / 1 lb. of gain.
 Daily hand feeding is recommended.
 Evaluate feed by Gain / kg. fed (not price)
 Floating, sinking, or slow sink feed?
What influences fish feeding?
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Temperature
Stress
Disease
Weather
Water Quality
Palatability of the feed (fish oil /antibiotics)
Dominant fish behavior
Feed characteristics
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% Protein: % Fat level (ex: 42%P:16%Fat)
Type of protein: plant or animal
Moisture content
Vitamin levels
Density (float or sink)
Pellet diameter: fish size
Freshness (store on pallets in cool room)
Commercial Feeding: how often?
 Young fish: 4 to 10 times per day
 Juvenile fish: 2 to 4 times per day
 Larger fish: 1 to 2 times per day
Commercial feeding: how much?
under ideal conditions
 fry: 5 to 10% body weight / day
 Juvenile fish: 2 to 5% body weight / day
 Large fish: 1 to 2% body weight / day
How do you minimize waste?
 Research shows that high energy feeds (42% protein,
18% fat) can reduce solid waste versus the standard
ration (38:12).
 The “extrusion” process pre-cooks the feed to allow for
higher absorption and lower amounts of solid waste.
 Routinely check feeders for proper adjustment. Hand
feed carefully, record daily feed used.
 Handle feed bags with care.
 Design for best water flow (settle and concentrate
solids)
Fish Feeding Methods
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Hand feeding (observation of behavior)
Belt feeders
Demand feeders
Automated feeders
Medicated feeds can control disease
Specialty finishing feeds can add color
Demand Feeders save labor
but may waste feed or underfeed
Automatic feeders
Need proper adjustments
Feed and Water Quality
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Feed increases oxygen use.
Increases ammonia production
Increases algae in the pond.
Increases bacterial populations.
Reduces water clarity.
In cages: low dissolved oxygen
syndrome (LODOS).
Oxygen Biology
 Trout require at least 5 mg/l dissolved
oxygen for good growth.
 Oxygen is a product of photosynthesis,
which requires sunlight to convert CO2 into
a source of food for fish.
 Plants, fish, bacteria, and algae all consume
oxygen in ponds.
How does oxygen enter a pond?
 At the surface, oxygen enters from the air.
 Aeration will improve the rate that oxygen
enters the water from the air.
 Wind will also improve the rate that oxygen
enters the water from the air (more contact
aera).
 Under the surface, from plant photosynthesis.
 In-flowing water – spring or runoff
What can aeration do?
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Increase dissolved oxygen in water.
Reduce oxygen related stress.
Reduce carbon dioxide in water.
Reduce ice formation with water movement.
Help to precipitate iron (ferric ions).
Increase carrying capacity – feeding rates.
De-stratify (mix) the water layers.
Pond Oxygen Facts
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Algae are the greatest oxygen consumer.
Oxygen is lowest in the early morning.
Early morning is the best time to visit.
Some fish will seek out oxygen when low.
The pond surface is where O2 transfers.
Wind is a natural aerator.
Cloudy days reduce photosynthesis (O2).
Cage culture and LODOS.
Oxygen: Daily Cycles
Metabolic Waste reduction:
dissolved /suspended
 Approximately 30% of the feed will become
solid waste.
 Quick concentration and waste removal
from system is best (in recirculation systems).
 Good feed handling, storage, and routine
on farm will reduce “dust particles”.
 Size of waste matters: settling rates
fragmentation causes leaching of nutrients.
Forms of Waste
 Metabolic Waste (solid and dissolved)
 Chemical Waste (dissolved)
 Pathogenic Waste (microscopic)
 Dissolved Waste: phosphorus, BOD, COD,
nitrogenous waste is toxic to fish (NH3, N02) Each of
these are a result of feed inputs.
 Solid Waste: fish, feces, algae, & bacteria will
contribute to dissolved waste. By reducing solid
waste, dissolved waste will also be reduced.
Wastewater Treatment Options
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Settling ponds ( particles >150 microns)
Sediment traps
Microscreens (>60 microns)
Filters: drum, bead, sand , fluidized bed
Foam Fractionators (<30 microns)
Constructed wetlands (dissolved waste)
Hydroponics (SRAC # 454)
Cornell-type dual drain
For rapid concentration and removal of solids
Low volume (10%)– High solids center drain
High volume (90%) – Low solids side drain
Water Treatment levels
Primary: settleable solid removal…
fish food and feces
Secondary: dissolved solid removal
ammonia, nitrite, phosphorus
Tertiary: chemicals and pathogens
How to Dispose of Waste?
 Permitted Land Application
 Composting: Combine with wood chips
or saw dust to attain a C:N ratio of 30:1
Requires aeration, layering, monitoring
 Constructed Wetlands (dissolved waste)
 Neutralize pathogens with ozone,
chlorine, or ultraviolet radiation (UV).
In-class assignment
 A trout farm needs to produce 100,000 lbs.
of 1 lb. trout for the holiday season. Assume
the fingerlings are 3”-4” (10 gms) and will
convert the feed at 1.3 lbs. feed / lb. fish.
 If high quality trout feed costs $0.42/lb, how
much will it cost to produce 100,000 lbs.
 If the waste has 2% nitrogen, how much
carbon in the form of wood chips or saw
dust would be needed to turn the fish waste
into a mulch.
Paired
Concrete
Waste
Basins
with
Tiles –
Waste is
carried
in trunk
line by
gravity
into the
basins.
photo
Tiles line
the bottom
of the basin.
Sludge is
mixed with
a flocculent
to bind the
solids.
Water then
drains
through the
slots in tiles
and goes
into the
receiving
waters
Geo Bags or Dirt Bags:
Used for Solids Collection and
Removal
Marine Biotech’s “CycloBio”, a fluidized bed
bioreactor is efficient in converting (dissolved)
toxic ammonia to nontoxic nitrate.
Mulching pile with aeration and wood chips
from trout processing plant
Chemical Waste Management
 Proper biosecurity measures will help reduce
the need for antibiotics, disposal of
mortalities, and chemicals to treat sick fish.
 The use of chemicals on fish farms is
regulated by state and federal laws. Very few
chemicals (besides salt, formalin, and a few
antibiotics) are allowed to be used on food
fish. Regardless of the types of chemicals
used, a detoxification procedure should be
followed, according to the manufacturer’s
label. Prevention works best.
Pathogenic Waste Management
tertiary treatment
 Pathogenic waste reduction
 Types: Parasitic, bacterial, and viral
 Methods of reduction: chlorination,
ultraviolet radiation (UV) and ozonation.
 UV does not cause fish kills, is relatively
inexpensive, and is not a threat to workers.
 Most countries laws do not require
pathogenic treatment for fish farms.
Ozone – UV – Chlorine –Virkon-S
 Ozone: very effective, requires monitoring indoors,
can damage lungs, needs special materials,
expensive to use, can kill fish at low levels.
 UV: safe to use, needs particle-free water, low
maintenance , moderately expensive.
 Chlorine: caustic, caution required for safety, can be
inexpensive, some pathogens are resistant.
 Virkon-S: broad-spectrum disinfectant, long lasting
Ultraviolet sterilizers are
safe and efficient in destroying
viral and bacterial pathogens.
Low pressure mercury type UV lamps are best suited for
germicidal action.
Factors that decrease radiation: particles in the water, lamp
sleeve, age of bulb, wavelength (265 nanometers is best).
Waste Generation
per day/ 1000kg live weight
Animals
Catfish
BOD5
(kg)
0.8-1.3
Solids
TKN
Sludge
(kg)
(kg)
Volume
3.9-6.3 0.2-0.32 65-630liters
Beef
Cattle
Dairy
Cows
Poultry
1.6
9.5
0.32
30 liters
1.4
7.9
0.51
51 liters
3.4
14
0.74
37 liters
Swine
3.1
8.9
0.51
76 liters
Review of Best Aquaculture
Practices (BAP’s)
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Minimization of waste: management
Use high energy (extruded) feeds.
Good feed management. (method, pellet size)
Design: rapid concentration and removal.
Use settling ponds, clean regularly.
Use dual drains in circular tanks.
Keep good records. Monitor results.
Maintain water treatment system.
Answers
 100,000 lbs. of trout x 1.3 (feed conversion) =
130,000 feed x $0.42/lb. = $54,600
 130,000 lbs. feed x 30% waste = 39,000lbs.
so 39,000 lbs of waste x 2% nitrogen = 780lbs
so 780 lbs. nitrogen will need (780 x 30) 23,400
lbs. of carbon to create mulch from the waste.
Additional Resources
 A Fish Farmers Guide to
Understanding Water Quality:
http://darc.cms.udel.edu/AquaPrimer/wqualityas-503.pdf
 Aquaculture Network Information Center:
www.aquanic.org/oindex.htm
 WVU Aquaculture website:
www.wvu.edu/~agexten/aquaculture/index.htm
 Aquatic Eco-Systems – www.aquaticeco.com