Tuesday, February 23, 2016

Tilapia cages. What makes a good one?

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.
Plastic pipe
Lightweight, inexpensive and readily available, easy to fix
May deteriorate in the sun
Lightweight, doesn't rust
Needs to be a good quality otherwise will bend with weight of fish
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.