Feeding and maintenance in rice-fish system
Daily check the water level in the field to see that it is not
rising or falling unusually quickly. If this occurs, find out what is causing
it. Any leaks should be unclogged. A shovel or hoe should be carried on these
visits. Some farmers throw a little feed every day in order to monitor their
fish stocks. In intensive systems, early morning checks to see if fish are
gaping is advisable.
FEEDING AND FERTILIZING
Feeding and fertilizing should normally help fish grow. However,
it is not a major consideration in lightly-stocked fields (below 3000/ha), where
fish should be able to forage sufficiently for themselves.
Families who would like to stock more heavily (and therefore to
feed and fertilize) need to consider the following points: a) Will they have
time to feed or fertilize well? (How far away is the field from their house?
What other work do they have to do?) b) Can they get-feed or fertilizer? Is it
easily available in the area? Is it affordable?
Feeding and fertilizing
TYPES OF FEED AND FERTILIZER
It is difficult to draw a line between "feed" and "fertilizer,"
especially since manure can be used as both. Inorganic fertilizers can be used.
So can any non-toxic organic material.
Manure is often the most important addition, by weight. Either
fresh or dried manure can be used. A little caution with fresh manure may be
needed if water is stagnant, but it has been observed that up to 300 kg/ha per
week go into such systems without causing harm. Replenishing manure as the fish
consume it is another way to cope.
Rice bran is commonly used as a fish feed. It works well in
nurseries, but is usually not needed in extensive rice-fish culture. If farmers
have to pay for it, they probably should not use much, once fish have entered
Some farmers use rice hulls in their systems and some fish
species eat these eagerly. Most of the hull is not digested, but gets spread
around the field by the fish.
Kitchen wastes and leftovers of any kind can be given.
Different kinds of water plants work well: Azolla, Wolffia,
duckweed (Lemna), pak boong or kangkong (Ipomaea aquatica) and water mimosa are
examples. Different fish species will have different preferences but silver barb
will eat any of these.
Crop by-products are also acceptable: cabbage leaves and corn
cobs have been used by some farmers. Cassava leaves are also popular. Since
some-cassava varieties may be poisonous, it is advisable to dry cassava leaves
before feeding them to fish.
Termites are a very nutritious feed and are especially helpful
in nurseries. Nests are chipped over the pond or field and the termites fall
into the water, where they are rapidly consumed. Termites are usually not needed
once fish have entered the rice field; if farmers continue to use them heavily
throughout the season, they may run out of nests! Other insects, shrimps and
worms are similarly nutritious.
Rice straw is not usually eaten directly by fish, but feeds
small plants and animals on which fish feed. It can be used anywhere, but may be
especially helpful in turbid nursery ponds.
Any otherwise unused dead animals, entrails or body parts can be
put to use. In rice fields, they can go directly into the water for fish
consumption. In nursery ponds, large, decaying animals can contaminate the pond.
Some farmers suspend animal parts over the pond. These attract flies, which lay
eggs on the meat; maggots can then be knocked off the meat into the water to
feed the fish.
Jute or kenaf resting can make water temporarily unsuitable for
fish culture. The water turns black, oxygen levels drop to near zero and the
water smells bad. The resting is very effective, however, in clearing up turbid
water. After the resting is finished, pond water quality is often improved.
Also, small amounts of jute or kenaf will not harm fish and the rotting material
provides feed. Larger amounts can be placed in stagnant water. Good figures for
"safe" rates for fish, unfortunately, are not available, so only small amounts
should be used and the fish should be checked every morning to see if they are
Other examples of feeds include mulberry leaves, banana leaves,
bat dung, animal feed leftovers, coconut oil residues, Leucaena leaves and
livestock dung. No list of potential feed stuffs will be complete.
In densely-stocked fields (over 5000/ha), continuous feeding and
fertilizing become important, particularly as the fish grow. Giving small
amounts of feed a couple of times a day may be advisable. Check to see how
quickly a known amount of vegetation or manure gets consumed. If some amount
remain after an hour, there is no need to increase the rate. If it disappears
within half an hour, increasing the amount is advisable.
Prepared by: JOHN SOLLOWS
FARMER-PROVEN INTEGRATED AGRICULTURE- AQUACULTURE:
TECHNOLOGY INFORMATION KIT (II RR- ICLARM)
The presence of important numbers of predators can affect size
and species stocked. Large fish escape predators easily, but this appears a less
important consideration for silver barb than for other cultured species.
Culture field characteristics will often affect number and
species stocked. Occasionally, silver barb will not grow well in field with very
shallow water (less than 10 cm). In small fields, the farmer may find the
advisable number of fish limited by available area. On the other hand, there is
nothing wrong with stocking few fish in a very large field, especially if this
is all the farmer can afford.
.The suggested rate of 3,000/ha can be increased if the field
has stable water depth (30 cm or more is preferable) and if the field can be
fertilized frequently. If fish are fed, the feed should be put in the field, not
in the refuge. Otherwise, they will stay in the refuge, the rice will not
benefit and the fish will become overcrowded. Farmers should be very cautious
about stocking over 6,000/ha. This can work occasionally, but should be done
only by experienced farmers who know their system.
Small fry can be stocked in greater numbers than large
Note: This paper refers to stocking fry and
fingerlings, not hatchlings.
If stocking density is low, there is
often sufficient natural food in the paddy and no feeding is necessary.
If stocking density is increased,
natural food in the paddy is not enough and production is low.
If stocking density is increased,
maximum production can still be obtained with supplementary feeding.
Prepared by: JOHN SOLLOWS
FARMER-PROVEN INTEGRATED AGRICULTURE-AQUACULTURE:
TECHNOLOGY INFORMATION KIT