Tilapia

Oreochromis mossambicus or Mozambique Tilapia at the Cincinnati Zoo. Photo by By Greg Hume (Own work)

General

• Nile tilapia grows to 9 lb and 9 years old - [1]
• Overview of integrated growing with duckweed and algae - [2]
• UFG design basics - [3]

Tilapia growing on Kelley Hot Spring Fish Farm west of Alturas, California, USA

Temperature

• Best temparature is 72-90F - [4]

Grow Beds

• 1:1 ratio - but of what? Volume tank to volume grow bed.
• 1 cubic foot of grow bed for every pound of tilapia - [5]
• 6-10 gallons of water for every square foot of deep (12") grow bed - [6]
• If we have an excess of water, then the limiting factor to the fish stocking is grow bed area. Now this will depend on other systems - such as duckweed

Duckweed Assist

• If duckweed is cultured in addition to plants, how much filtration does duckweed perform?
• Duckweed and watermeal on ponds - [7]

Growth Rate

• Exponential, linear, and plateau growth rates are the normal course of life of a tilapia. Depending on the genetics, the growth rate is linear up to from 1-3 lbs of weight. Linear phase starts at 100 grams, and before that, the rate of weight gain increases. - [8]
• It takes 6-12 months until harvest. - [9]
• 2% average growth rate of tilapia - [10], but .7% if fed duckweed alone - [11].
• 1-3% in linear stage - [12]
• Fish growth in lenght is linear, but weight gain is overall exponential in the general case - [13]

Stocking Rate

• 1/4 lb per gallon without supplemental pure oxygen. With oxygen, stocking up to 1 lb per gallon is possible. -[14]. .25 lb per gallon means 250 lb per 1000 gallons, or 1000 lb per 4000 gallons.
• 5-9 lbs per cubic foot with oxygen - [15]. Same? 1 cubic foot = 7.5 gallons. Thi
• Bright Agrotech - correct stocking rate of 1 lb for 8-10 gallons of water - [16]. This rate allows for flow aearation, as opposed to air pump aeration - allowing the splash of flowing water to provide adequate oxygen. Summary: this figure is 1/2 or less the MSU publication above - so consistently conservative.
• 3 gallons to one pound of fish - [17]
• 1 lb per 5-10 gallons of water - [18]
• Thus - conservative estimate of 1 lb per 10 gallons of water - gets us 400 lb of fish mass. 4 lb of fish per day.

Stocking Rate for Fry

• Southeast Asia stocking of fry - not adult carrying capacity of the water - .7 kg/m2 - [19] - if 1 meter deep, that is 264 gallons

Feeding

• In tilapia monoculture systems, animal manures stimulate phytoplankton which the tilapia feed on - [20]
• Tilapia can feed on duckweed alone with a 1:1 fish conversion ratio. Feed Conversion Ratio is best on duckweed alone, though the growth of the fish was half of that on a mixed diet. - [21]
• 1% of body weight feeding rate is recommended - [22]