|Better Farming Series 38 - Better Freshwater Fish Farming: Raising Fish in Pens and Cages (FAO, 1990, 83 p.)|
1. In booklet No. 30, Better freshwater fish farming: the fish you were told that you can put your baby fish in a pen or a cage in one of your fish ponds until you are ready to use them.
Put the baby fish in a pen or a cage
2. Pens and cages can also be used for raising fish from the time they are babies until the time they are big enough to eat or sell.
3. If you have a stream, over lake or reservoir nearby, you may want to build a pen or a cage and raise fish there.
4. If you already have a fish pond you may want to put in a cage or two so that you can raise more fish than you could in one pond alone.
5. Raising fish in pens and cages is somewhat different from raising fish in ponds. Let us begin by looking at some of the differences.
6. One of the biggest differences, and perhaps the most important, between raising fish in ponds and raising fish in pens and cages is feeding them.
7. As you know, with a pond you fertilize the water. That is, you add compost, animal manure or plant materials so that there will be natural food for the fish to eat.
8. In addition, fish in ponds must be given other kinds of food each day. This is to make them grow quickly.
9. With well-fertilized water and enough of the other kinds of food, the fish can swim about and find food anywhere in the pond.
10. However, with a pen or a cage built in a stream, lake or reservoir, there may be little natural food and the movement of water may carry the food that you give the fish outside the pen or cage where the fish cannot get it.
11. So, with pens and cages you must take greater care that the fish have enough to eat, that me food Is very rich and that it does not float away before the fish can eat it.
movement of water may carry the food out of a pen or cage before the fish can eat
be sure to feed in such a way that the fish can eat before it floats away
12. It is always a good idea to put a fish pond near where you live so that you can easily take care of it and watch that people do not try to steal the fish.
13. You can usually find a place near your house with the right kind of soil to build a pond.
14. If there is no water there, you can dig a water supply ditch and bring water to the pond.
15. However, with a pen or a cage you must find a place where there is water already.
16. So, you may have to go quite far from your house to find a stream or a lake which would be good for a pen or a cage.
Find a stream or a lake
17. This may make it hard to take care of the fish and watch that people do not steal them.
18. Remember, it is very easy to steal fish from a cage because all of the fish are in a very small space and they can be taken quickly with a net while you are not watching.
Figure Work, time, materials
19. To dig a pond is hard work, and the bigger the pond the longer it takes. If you dig a pond all by yourself it will take a very long time.
20. However, to dig a pond you do not have to spend very much money.
21. The only building materials that you need for a pond are for the inlet and outlet and for the overflow.
22. To build a pen or a cage is less work than digging a pond. It is easier to do by yourself and it takes less time.
23. However to build a pen or a cage may cost you more money. Pens and cages are built of bamboo or wood and closed with fish net, woven material or plastic mesh.
24. You may have to buy some of these materials if you decide to build a pen or a cage.
Loss of fish
25. With a pond, if you are careful to cover the outlet and the overflow with screens there is little danger of losing fish.
26. However, with a pen or a cage that is covered with fish net, woven material or plastic mesh you must be more careful.
27. A pen or a cage can be easily damaged by animals in the water or rubbish such as logs or tree branches. So, there is greater danger of losing fish.
Damage a pen or a cage
28. The first time you stock a pen or a cage you will need some baby fish.
29. If you have raised fish in ponds and have built your own nursery pond you may already have baby fish.
30. If you do not have your own baby fish perhaps you can get them from another fish farmer or from a fish culture station.
Get baby fish
31. After you have built either a pen or a cage you can raise baby fish in it as well. You will learn more about this later in this booklet.
32. Now let us begin to learn how to build pens and cages and how to raise fish in them.