Caring for Tilapia

Due to their hardiness and flavor, delilcious tilapia fish have been a favorite fish to raise since ancient times. In Ancient Egypt, tilapia were revered as a symbol of fertility and the renewal of life, possibly due to their resilience, reproductive fertility and unusual habit of females of protecting their eggs in their mouth to incubate till hatching. Tilapia, also called St. John's Fish, are native to Israel, and thrive in the Sea of Galilee. Tilapia like warm water, can live in fresh, brackish, orsalt water, and have excellent tasting, firm, white meat. 

Keeping the Balance

To grow healthy fish, we need to maintain a balanced pond ecology of: fish feed, number and size of fish, oxygen in the water, waste that accumulates in the water, exchange rate of new cleansed water, and uptake of the waste-nutrients by plants, duckweed and algea.

Feed - Tilapia eat plants, love protein-rich duckweed (equal in protein to commercial fish feed) and also filter algae from the water using tiny combs in their gills. Combining duckweed and commercial fish feed is good, but tilapia grow ok on duckweed alone. As concerns about mercury contamination in fish increases, pond-raised tilapia are a safe toxin-free food because they do not build up environmental pollutants in their meat - unlike the wild carnivorous predator or scavenger fish species. Vegetarian tilapia with scales are kosher to eat according to Jewish dietary guidelines.

Stocking Density: The number of fish your tank can hold is determined by the levels of food, ammonia and oxygen. Figure a stock density of about 1/4 lb of fish per gallon. Higher stock densities (1/2 to 1 lb/gal) require added aeration and high treatment levels. Using the 1/4 lb/gal for production capacity, you can calculate how many fish of a given weight can be stocked in the tank - more smaller fish or fewer larger fish. Maximizing tank production capacity by effective water treatment in the plant troughs improves the economics of tilapia production.Tilapia can grow from baby fingerlings to eating size in about six to eight months in optimum environments.

 Water Quality:

Key indicators of water health are:

- dissolved oxygen (DO) so that the fish can breath. Oxygen is introduced by waterfalling the cleansed water back into the fish pond.

- ammonia (NH3) waste that is accumulates in the water. Ammonia is toxic to the fish, and treated by absorption, biofiltration and settlement.

Good water quality monitoring testkits and manuals can be ordered from GREEN.

 

Plants cleanse water at: <ecological-engineering.com>

 

Cleansing the Water: Pure water is maintained by:

a. absorbtion of waste by duckweed amd algea that convert nutrients into biomass fish feed.

b. biofiltration (conversion) of amonia into nitrite, then nitrate by teeming microorganisms on plant roots and rock surfaces into a usable for for plants, and

c. settlement and removal of fish waste, uneaten food and dead algea

 

Waste is absorbed by duckweed, 35% protein, that floats on the water surface, does not contribute oqygen and can be a complete food for tilapia. Best to grow in separate shallow tanks.

 

Algea are tiny aquatic plants that live on sunlight and waste-nutrients, contribute oxygen to the water and are filtered by tilapia for food.

 

Biofiltration habitats with rock and plant-root surfaces and air for bacteria that convert ammonia to nitrate plant food

 

Settled sludge waste that sinks to the pond bottom is removed and vermicomposted.*

 

Breeding: A steady supply of new fish requires care that people collect the eggs from the brooding females, incubate them and protect the tiny newly hatched babies. Keep the baby tilapia in a separate tank. They like to eat blended-up duckweed and filter the greenwater rich in algea.

 

Eggs from brood fish.*

 

Newly hatched baby tilapia.*

 

Type of Tilapia: We grow Nile tilapia, Oreochromis niloticus, due to their ease of care and availability.

Market: Tasty tilapia are second only to salmon as a popular farm-raised fish world-wide.

* Racocy - Virgin Islands Aquaponic Inst.