Fish Selection for Tank
Culture and Feeding Systems
Gary J. Burtle
University of Georiga
Animal & Dairy Science
Tifton, GA gburtle@uga.edu
229-386-3364

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

Live Food Culture

Brine shrimp for small fish
Aeration and a light source are required.
Salt water to hatch cysts.

Artificial Feed for Small Fish
Finfish Feed
50% protein, small particle, Zeigler

Tilapia Fingerlings in Tank
With Clear Water

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
• 28 to 36%
• > 4%
• 80 mg/kg Stable C
• Complete (12 items)
• P, Zn, Co, Cu, I, Se,
Mg, Fe, Ca
• Note: Stock at >8 catfish per cubic foot

Potential Bluegill Diets
Ziegler
Silver
Protein 40
Rangen
400
41
Aquamax
500
41
Silver
Cup
40
Fat
Fiber
Ash
10
4
8
12
5
8
12
4
10 -
-
12

160
140
120
100
80
60
40
20
0
Bream Growth in Recirculating
System, 200 days (7 months)
1/3 lb
BG-M
BG-F
HY-M
HY-F
0 50 100 150 200

1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Growth of Israeli Hybrid Tilapia
(pounds over weeks)
1.3 pounds of gain
In 200 days
Lb/fish
1 9 17 25 34

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

Hybrid Tilapia at 800/1200 gal

Green Water Culture

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

Simple Culture Tank and Sludge
Removal Tank

Partitioned System for
Catfish/Shrimp and Tilapia
Tilapia Area
Catfish Area

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)

Exposed Tilapia Tank with High
Rate Aeration
BIOFLOC
PRODUCTION =
BROWN WATER

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.

Bacteria, algae, protozoa

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
10
20
30
40
50
60
Feeding rate Lemna Survival rate
(g DM/kg fish) of fish (%)
97
100
100
60
27
17
0.2
0.4
1.0
1.0
0.7
0.8
Mean LW gain Conversion
(g/d)
1.9
1.9
1.6
2.3
3.3
3.3
of Lemna DM to fish liveweight (g/g)

Bottom Line
• Use green water to reduce cost
• Stock the fish that you can sell at a good price
• Use supplemental feeds to finish out the fish
• Tilapia still are the best candidate for tank culture as food fish
• But, less regulation of bluegill or catfish.