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Fish Selection for Tank Culture and Feeding Systems
Gary J. BurtleUniversity of Georiga
Animal & Dairy Science Tifton, GA
Feeding Indoor Tanks
• Absolutely need a complete feed– Also needs to be digestible
• May supplement with natural food or vitamin-rich products
• Feed every day, or multiple times/day
• Use lighting to grow algae on tank sides
Some Food Items
• Natural foods– Fly larvae, worms, brine shrimp, meal worms
• Ground meat– Beef liver, egg yolk, shrimp, fish paste
• Yeast– Brewers, specialty
• Food waste - vegetable
• Fertilizer – for greenwater or biofloc
Tilapia Nutrient Requirements
• 25 to 30% protein
• Can use plant materials effectively
• Fiber should be kept low
• Fat should contain linoleic (n-6) fatty acids, about 1% of diet
• A complete vitamin and mineral supplement is needed for tank culture
Bluegill Nutrition Notes
• Natural diets contain about 20% plant material
• Large zooplankton, insects and crustaceans make up most of the diet
• Therefore, bluegill are carnivorous– A relatively high protein (35 to 40%) and high
fat (10 to 15%) diet is recommended
Catfish Nutrient Requirements
• Protein• Fiber• Vitamin C• Other Vitamins• Minerals
• Note: Stock at >8 catfish per cubic foot
• 28 to 36%• > 4%• 80 mg/kg Stable C• Complete (12 items)• P, Zn, Co, Cu, I, Se,
Mg, Fe, Ca
Potential Bluegill Diets
ZieglerZiegler
SilverSilver
RangenRangen
400400
AquamaxAquamax
500500
Silver Silver CupCup
ProteinProtein 4040 4141 4141 4040
FatFat 1010 1212 1212 1212
FiberFiber 44 55 44 --
AshAsh 88 88 1010 --
Bream Growth in Recirculating System, 200 days (7 months)
0
20
40
60
80
100
120
140
160
0 50 100 150 200
BG-M
BG-F
HY-M
HY-F
1/3 lb
Growth of Israeli Hybrid Tilapia(pounds over weeks)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1 9 17 25 34
Lb/fish
1.3 pounds of gainIn 200 days
Tilapia Feeding System
• Green water or small pellet feed for first three months
• Supplement with a 28% protein feed for final 3 months
• Feed conversion is expected to be 1.5 pounds of feed per pound of fish and could be better
What is Green Water?
• Usually a blue-green algae/water mixture
• Needs open air or greenhouse environment
• Nitrogen and phosphorus provided by feed or fertilization
• Other systems (“green manure”)– Duckweed– Azola water fern
Tilapia in Green Water
• Green water provides a basis for nutrition, usually for smaller stages of fish
• Prepared feed is used to finish the fish later in the growing season– Feed quality and cost can be lowered by the
presence of green water
System Requirements to use Green Water
• Light from the sun or grow lights
• Heat source for the water
• Aerating system
• Sediment collection system
Production from PAS
• Tilapia in two 8 ft compartments of the system (0.33 acres)
• Stocked at 400 to 800 per compartment• Resulted in about 1,000 pounds of Tilapia• Reduced aeration requirement and
improved water quality for catfish/shrimp production (6,000 pounds of catfish)
• Algae was reduced from >100 mg/L to about 50 mg/L by Tilapia (less blue-green)
What is Biofloc?
• Each floc is held together in a loose matrix of mucus that is secreted by bacteria,
• bound by filamentous microorganisms,
• or held by electrostatic attraction.
• also includes animals that are grazers of flocs, such as some zooplankton and nematodes.
• NEEDS A HIGH RATE OF AERATION.
The effects of feeding tilapia increasing levels of DUCKWEED. Tilapia were held in static water in concrete tanks (Hassan and Edwards 1992). The fish initially weighed approximately 41g
Feeding rate Lemna Survival rate Mean LW gain Conversion
(g DM/kg fish) of fish (%) (g/d) of Lemna DM
to fish live-
weight (g/g)
10 97 0.2 1.9
20 100 0.4 1.9
30 100 1.0 1.6
40 60 1.0 2.3
50 27 0.7 3.3
60 17 0.8 3.3