Although you may have
heard that the tilapia can be successfully reared in a cage, you may
not have realized just what is needed. There are some I have seen on
sites such as Ebay. These are a thin netting material with floats.
Often these will be for very young fish as the material is not robust
enough for adult fish. A cage in many ways is preferred to rearing
in a tank because the fish waste drops through the cage to the bottom
of your lake or river.
Here on our farm we
have used a few different types, some are better than others for
various reasons. Here are a few things to consider.
The frame. What
material is the frame made of? This could be aluminum, wood or
plastic pipe. Each has its advantages and disadvantages.
|
material
|
Pros
|
Cons
|
|
Plastic pipe
|
Lightweight, inexpensive and readily available,
easy to fix
|
May deteriorate in the sun
|
|
Aluminum
|
Lightweight, doesn't rust
|
Needs to be a good quality otherwise will bend
with weight of fish
|
|
Wood
|
We used Hardwood which lasts
|
Can be heavy to lift, out of the water could be
prone to insects.
|
Besides the frame which
will hold the netting or the structure of the cage. For this we have
used two types. One was a heavy duty plastic, the other was plastic
coated metal. Similar to a chain link fence.
Over time both of these
needed repairing as areas would become holed and allow fish to
escape.
Every time the cages
came out of the water for the fish to be sold, they get cleaned and
thoroughly checked for potential problems. The plastic ones we repair
with strong cord, and the metal ones we use coated wire to patch up
areas.
You also need a way of
making the cages float as you do not want the cages sitting on the
bottom of your body of water. We use plastic cans which in their
previous lives were used for cleaning products. These were perfect
but after two years in the Brazilian sun, needed replacing as they
became brittle and would crack and take on water.
This is why, during
feeding time, it is always a good idea to do a quick visual scan of
the cages to preempt any potential problems. Keep extra buoyancy aids
in a covered area. It would be a shame to see all the fish in your
cage escape due to a listing cage.
We had a local welder
construct small cages to hold the containers in place. These simply
hooked over near a corner. On our 2m x2m cages we use 4 floats. On
our 2m x 3m we use 6 floats.
As well as the frame,
the cage material, and the floats you will also need to put fabric
mesh around the top edge of the cage. Ours was about 18” wide. At
first this doesn't seem necessary but when you feed the fish in the
cage, this mesh will keep the food from floating out of the cage and
being wasted. This should be tied onto the cage to keep it from
floating up, which trust me, is a nightmare.
The last item you will
need is plastic mesh for the top of your cage. This serves a couple
different purposes. One is to keep the fish in the cage. Although you
may think that tilapia don't jump, they will. With a cage which is
just floating above the height of the water, they will be out in a
shot. The second reason is to keep out birds. We have had herons,
egrets and moorhens all sitting on our cages. The herons and egrets
are trying for the fish and the moorhen is eating the fish food.
