Is the principal form of aquaculture, while other methods may fall under mar culture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food and monetary purposes. Fish farming creates employment opportunities for the owner and his/her workers. A facility that releases juvenile fish into the wild for recreational fishing or to supplement a species' natural numbers is generally referred to as a fish hatchery. Worldwide, the most important fish species used in fish farming are Hecrobrancus, carp, salmon, tilapia, Eguand catfish.
According to wiki; "Fish demand in Nigeria and world over is for the sack of protein, which has resulted in widespread fish farming in world over. Fish farming offers fish marketers another source. However, farming carnivorous fish, such as hectobrancu and egu, does not always reduce pressure on fisheries, since carnivorous farmed fish are usually fed fishmeal and fish oil extracted from wild forage fish. In this way, the Hecrobrancus can consume in weight more wild fish than they weigh themselves. The global returns for fish farming recorded by the FAO in 2008 totalled 33.8 million tonnes worth about $US 60 billion. There are two kinds of aquaculture: extensive aquaculture based on local photosynthetical production and intensive aquaculture, in which the fish are fed with external food supply"
How To Construct A Fish Pond: Principles
------, heavy equipment is most effective as larger distances to move earth make
hand labour costly. Work crews building fish ponds require --------- for quality
pond construction.
b. --------- are removed from the site, later to be placed on top of dikes for sowing with
----------
c. A general survey of the site showing elevations, angles and distances is useful for
designing the Catfishfish farm pond lay out, showing water canals and drainage canals. Ponds
should be staked out with ----- to show-------- lay out for tops and bottoms of dikes.
d. The shallowest depth for production ponds should be no less than ------------- and the
deepest waters should be at least -------------- depending on the slopes. Brood ponds
for reproduction should be more --------------
e. Pond ----------- are hard and -------------- or obstructions and ------------
towards the central ----------.
f. Pond dikes are to be compacted every ---------- of soil depth. ---------- is very
important and cannot be forgotten. Manual-------------- is done with laborers using earth
----------------and will assure no seepage of water. This will later minimize
water use and greatly reduce repairs and maintenance costs. Dikes can be washed out
from leaks that enlarge as water flows through them.
g. The most efficient and low cost pond construction uses ------------ to build (fill)
the dikes. So “---------------should equal Fill”.
h. Slopes on the inside dikes should be ----------up to ------------, whereas outside slopes could be
steeper at ----------- to -----------. Gentle ------------ require less maintenance and lower cost in the long run.
i. The dike height between the water level and top of the dike is called the Freeboard and
should be ---------- cm depending on pond size. Standpipes or drain systems used should be
in place to allow over flow during rains to maintain the free board.
j. The entry pipe should be located above the ------------ and -------------. By having
facility to add water above the drain area, you reduce stress on fish during harvest and
you keep the fish from swimming out of the lowest area in the pond. (see Figure 3).
k. The stand pipe drain should be equipped with a screen having a large surface area to
allow over flow of water without loss of fish. Stand pipes are usually of ------- and have
an elbow that ---------- in the pond bottom at the point where the drain pipe goes through
the dike. Thus stand pipes can be “----------” to allow water to flow out of the pond.
l. Drain pipes under the dike require “anti seep collars” of concrete to avoid seepage
along the smooth------------; these collars also help stabilize the pipe.
m. Ponds should be fully drain-able all year round and should be open to receive
sunlight.
n. Harvest basin is very useful for efficient harvest of fish. These can best be
constructed with cement and bricks inside the pond of dimensions -------m x --- m x ----- m
deep (see photo in document).
o. In most cases, new ponds should be limed (Agriculture lime ------- kg/ha) and filled.
Fish should be stocked once the soils have become saturated with water….up to one
week after filling.
p. Dikes should be covered with----------- and sown with ---------- cover to prevent ----------.
q. Most ponds are rectangular with smaller ponds (--------------- m2) used for holding brood
fish and spawning and fry rearing. Fry are often raised in------------- or --------- to ------ g size as
this reduces predation and increases survival.
Records should be kept of all aspects of pond construction including labour, materials,
hire of equipment, etc. in the next lecture we shall treat in details types of catfish and source.
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