In aquaculture value chain, fish management is the mid-stream. The most important activities includes; fish feeding, regular change of pond water, sorting, stocking and fish stock assessment etc.
In feeding, fish feed should ideally provide the fish with fat (for energy) and amino acids (building blocks of proteins) and the fish food (pellet) must be speedily digested in order to prevent buildup of intestinal gas, kidney failure and infections (such as swim bladder problems and dropsy) and to avoid aquarium pollution due to excessive ammonia. Since there are different stages of catfish growth, there are different stages of fish feed; Fish feed are often denoted in mm, i.e.1.5mm feed, 1.8mm feed, 2mm feed, 4mm feed, 6mm feed etc There's also extruded (or floating) and non-extruded (or sinking) feed.
 Figure 1: Supplying 2mm blue crown feed to the fingerlings using spot feeding method
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Furthermore, due to their fragile nature, giving the juveniles feed
that isn't rich with the right nutrients can affect their long-term growth.
How often a fish is fed, it will differ depending on a lot of factors but for the results, group A got an average of 1.5kg to 2kg fish size in 6 months.
Fish can be feed using Broadcasting method or Spot Feeding method. Broadcasting method is less time-consuming and not more effective, while spot feeding method is time consuming and more effective, and it can carefully monitor their feeding pattern or behavior.
Water
quality monitoring
Change of water after
stocking it with fish depends largely on your management system which includes your
stocking density; the type of water used and the quantity of feed administered
to the fish.
High stocking density will
get the water dirty earlier because the more they are, the more the quantity of
feeds and feed wastes and also the more the wastes from them, high stocking
density will necessitate regular change of water for the fish.
In addition, contaminated source
of water and local feeds get water dirty easily and will call for regular
change of water. Generally, water in a fish pond or tank should be changed at
least twice or thrice in a week and also as soon as the oxygen level of the
water is low.
Therefore careful monitoring is carried
to ensure that the water oxygen level is maintained in its good quality as
nothing kills the fishes faster than bad water. When abnormal signs is
discovered from the fish; change their water, do not wait for later as every
minute counts in fish farming business.
To change the water in the
concrete ponds, the outlet channel of the pond is opened and water is allowed
to flow out gradually. But ensure not to completely drain the pond, small
quantity of the pond water is left and later mixed with the new water to enable
the pond water maintain its green colour. While in a rearing facility like
tanks, ensure that the water is completely drained out. Water Hyacinth can also
be added to the pond water to purify it to avoid constant change of water.
Figure 2: Water Quality Control and Management
Sorting
of Fish
In the course of culturing fish,
whatever feed given to them and no matter the kind of management, fish are not
likely to grow at the same rate. Some will definitely grow faster than the
other thus sharp shooters. Most of the time, bigger fishes do feed on the
smaller one. So to prevent this, it is therefore necessary to sort the fish. Sorting involve the process of
separating the bigger fishes from the smaller ones. Sorting will also increase
market price of the fish because there will be an opportunity of selling
smaller and bigger fish separately at any time and price.
How
often to sort your fish: This
depends on the number and how overcrowded they are. If they are properly
stocked for instance: using the normal stocking density then you may not have
to sort more than twice a month. However, there may be no need for sorting
again when the fish has reached a size when none can feed on the other.
The
best time of the day to do sorting:
Sorting is best done when the fish won’t pass through much stress. So early in
the morning or evening is recommended. However, whatever time is chosen but, they
should be starved for some hours prior to sorting so as to prevent crisis.
How sorting is done: To sort, you have to drain the water from the pond and then divide the fish into clusters or groups based on their sizes. Big bowls are needed for holding them during sorting. After separating them based on their sizes, and then return them back into their different pond according to their sizes. You can choose to have 2, 3, or even 4 different clusters.
Fish Stock Assessment
Fish stock assessment indicates
how well and state of the fish including water body. It involves the
collection, analysis and reporting of data on fish population. It’s mainly done
in open water where general fisheries are done. Various types of analysis are
carried out to improve the efficiency and sustainability during culturing and
management of fish (assessing your stock and its growth).
Figure 3: Assessing different clusters,
analyzing and keeping accurate data
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Some common types
includes: Cluster analysis, which is
used to group similar fish or ponds based on their characteristics, such as
growth rate, and feed conversion ratio etc. Regression analysis, it is use to model the relationship between
different variables, such as feed intake and growth rate, water temperature and
mortality rate etc. Survival analysis, it
is use to examine the survival rates of the fish over time, and to identify the
factors that affect survival. Growth
curve analysis, it is use to model the growth rates of fish over time, and
to identify the factors that affect growth. Water quality analysis, it is use to examine the physical, chemical
and biological characteristics of water and to identify the factors that
affects water quality. Others are;
Nutritional, Bio-economics and Risk analysis.
Stocking of Fish
During stocking of the pond with
fish, it is important to handle the fish with too much care. Ensure the fish
gets enough oxygen. Keep the fish from getting too warm or too cold, stock or
transfer fish early in the morning when temperature is low and fish are less
active. The stocking density must be according to the condition or size of the
pond.
Method
of stocking: Stocking
of fish should be done very carefully to avoid post stocking mortality. The
fish should be gradually and slowly lowered into the pond to enable it
acclimatize to the temperature and quality of water in the stocking pond.
D' Prime Aqua Consult is dedicated in empowering sustainability in aquaculture. Our team provides expert guidance and support to fish farmers, helping them improve their operations and increase productivity.
 Management: The mid-stream of Aquaculture Value Chain){kind=link}