Tilapia are the most commonly raised fish for Aquaponics applications. It does not matter if you are a large operation or a small home production Tilapia seem to be the fish of choice.
Why? The primary reasons are simple;
- Rapid Growth
- Early Reproduction
- Tolerates high density (you can house more fish per unit)
- Can tolerate higher water salinity
- Easy to feed (eat nearly anything!)
But raising Tilapia also has it's downside.
- Can quickly overpopulate
- Requires heating Temp range 82-92
- low tolerance for cold water (many can not tolerate temps below 72 without getting sick and dying)
Evaluate your system needs and if you will be able to properly heat your tanks before making the final determination of weather or not to Incorporate Tilapia into your plans.
Under the correct conditions Tilapia can grow to a pan size in as few as 4 months. So what are those conditions?
- Abundance of food
- Clean water
- Adequate aeration
- Proper tank size
- Temperature close to 90 degrees
Tilapia eat a variety of foods including Algae, grass, vegetable waste, water plants, dog food, commercial fish pellets, insects. If given the chance your Tilapia would prefer to feed on Algae first and everything else second, they have specially designed feeding systems to filter algae out of the water. Feed your Tilapia at least 4 times a day for optimal growth, but be careful not to over feed as that will cause both an ammonia spike in the water and foul the water with food remnants.
2. Clean water
Tilapia can tolerate higher concentrations of Ammonia, Nitrate and Nitrite than other fishes but those higher concentrations will weaken their immune system and may affect feed conversion (# of food: # of fish) and perhaps flavor. Females brooding eggs seem to produce more Ammonia and I have often noted a spike just before fry are released. If the water suddenly begins to cloud you have an Ammonia spike, don't bother testing the water, just do a water change to prevent losses!
Tanks holding greater than 200 gallons of water are more stable in this regard than smaller tanks and do not experience as many rapid water quality fluxuations.
In the home or commercial Aquaponics applications you will want to have at least as many gallons of growing beds as you do gallons of water in your tanks. This means for every 200 gal tank you want at least 200 gallons of growbeds to filter the water and support your fish. In this case more is better than less. You can always add fish if you need more nutrients for your plants.
3. Adequate Aeraton
Your Tilapia will need sufficient oxygen in their tanks to help break down Ammonia for the Nitrification cycle (Ammonia breaks down to Nitrate which breaks down to Nitrite for the plants to use). Without proper oxygenation your fish will be up at the surface trying to gulp air and will quickly die. Back up aeration is recommended in case of power outage to prevent losses. This can be done in the form of 12 volt oxygen pumps attached to a car battery to switch on when the power goes off.
4. Tank size
In the home or commercial Aquaponics applications you will want to have at least as many gallons of growing beds as you do gallons of water in your tanks. This means for every 200 gal tank you want at least 200 gallons of growbeds to filter the water and support your fish. In this case more is better than less. You can always add fish if you need more nutrients for your plants. This is not to say that you can not do Aquaponics with smaller tanks, only that you have to more closely monitor water quality. Test for Ammonia, Nitrate and Nitrite
Tilapia are warm water fish and as such are not cold tolerant. This is the biggest drawback to using these fish in both commercial and home Aquaponics applications. They prefer temperatures between 72-92 degrees and can tolerate temps up to 100 degrees or so, but on the cold side there is very little wiggle room. Depending on species they may be able to tolerate temps down to 60 degrees but you will experience a higher incidence of fungal infections and losses if your temps get that low.
Sexual Determination in Tilapia
Once your Tilapia have reached about 4 inches or so you should be able to see the sexual differences in the vent area of the fish. Refer to the photo above the fish on the left is a male and the fish on the right is a female.
Breeding groups are usually 1 male to 3-5 females. Aggressive males such as T. Honorum may need to be "lipped" to prevent them from damaging or killing the non-receptive females. Provide caves for the males to claim such as ceramic flower pots and a sandy bottom for them to prepare nests in.
The receptive females will enter the males cave and deposit her eggs then the male will fertilize them and she will scoop the eggs up into her mouth. They will do this several times before the clutch is completed.
When you see a female with eggs you should either carefully remove her to another tank or remove the other fish from the tank. removing the other fish is preferrable so that she does not loose any eggs in her struggles in the net. She will brood the eggs in her mouth and then the babies for some time before she releases them into the water. She can be very aggressive to other fish if there are any in the tank at this time. A female can brood several hundred fry in her mouth depending on size.
Tilapia are typically the fish of choice for the home or commercial Aquaponics project. They have both pros and cons to their useage in such systems. They grow quickly on poor quality feeds but the better the feeds you use the more nutritious the final product (meat) is and tastes. They breed early so you have the next generation growing while you are growing the parents. They can if allowed, quickly overpopulate a system. So separation of sexes as early as possible is desired. Or you can raise them in screened bottom tanks to prevent access to the bottom, forcing eggs to fall to the floor. This has one benefit of greater growth in the females as they do not eat while brooding eggs or young.
Aquaponics part 1
Aquaponics part 2
Aquaponics part 3