Massive death of fish in pond causes a considerable
concern for most fish farmers, followed by bad thoughts of being tricked by his
or her neighbor (sense of being poisoned) or may be fish have been stolen. In turn
fish farmers have been sent out of business and loss confidence due to
uncontrolled mortality rate.
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There are two forms of fish mortality:
A.Natural
mortality
Which is influenced by factors like
- Disease
- Competition
- Cannibalism
- Old age
B. Accerelated mortality
Involve intervention of other issues out of natural
condition like;
- Handling stress
- Transport stress
- Rapid change of water quality
- Poison
- Fishing activities
Fish may die at any time in the culture period, dead
fish tend to float on the surface and sometimes accumulate at the edge of the
ponds.
In
this chapter we shall look on possible techniques to control fish mortality.
The following are possible techniques that can help a farmer to control
mortality of his or her fish.
Avoid overcrowding of fish in small area for long
time during transportation, measurement or rearing of fish in a small pond.
Overcrowding of fish lead oxygen
depletion hence fish suffocate until they dead and also increase the chance of
disease transmission.
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| Overcrowding of fish encourage fish mortality |
Dead fish should be immediately removed from the pond
and proper measure should be taken like assessment of dead fish body to see if
there is any sign of disease or poison. Then after that proper disposal of dead
fish like landfill or being incinerated should be taken.
Transportation of fish should be done during early
morning (4.30 up to 5.00 am) or during night to avoid sunlight that may lead
temperature raise hence stress fish.
-Also order should be made at least 4 days to allow
preparation of fish and provide time
for fish to be conditioned.
Avoid overfeeding of fish
-Fish should be fed according to their size, proper time,
proper ration and fish response Avoid feeding of pond instead of feed fish
which in turn lead to eutrophication (excess accumulation of nutrients) that
cause algal bloom that depletes dissolved oxygen and secret harmful poison
(cyanide)
Picha
Measurement of fish and other fish handling
practices should not be done frequently, a farmer is advised at least twice in
a month to handle fish in order to reduce stress to the fish which may lead to
death.
*It is highly advised that all handling activities
to be done during the morning
Control water run off that enter in the fish pond
due to contain high amount of nutrients from septic tanks and streets in turn
affect water quality.
-Fish ponds should be constructed far from
households
-If possible build the ponds in a raised areas
Avoid use of expired feeds sold in the market/ due
to poor stored of feed
To avoid aflatoxin a farmer can use toxin binders in
case of any doubt and also farmer can do color observation as preventive measures.
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| Maize affected by fungus |
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| White materials like cotton wool in the fish feed sign of fungus |
*Fish feeds should be stored in a cool dry place,
should be placed above the crib to avoid direct contact with the ground.
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| Cribs used in carry sacks containg fish feeds |
Frequently checkup of fish pond; if there is a sign
of disease or any unusual signs in and around the pond, if there are long
bushes should be cutted to prevent hide site of predators and other bacteria
that tend to deposit their eggs in the grass.
Water coming directly from the river, dam, lakes and
stream should not allowed to enter in the fish ponds. Farmer is advised of to have
reservoir ponds that receives water and also enable farmer to treat water
before enter in the fish ponds.
Use of any type of chemical pesticides should be
done with extreme caution around fish ponds, spray of crops should be done in a
non-wind side to avoid spread of pesticide chemical to the fish ponds.
Prevent fish disease: This is enhanced by feed,
water, stress level e.tc.Disease can be cured by salt solution, drugs and
formalin depending on the type of infection.
For more information you can contact me through my
Email address: michaelkellya25@gmail.com or you
can leave your comment in comment box.
Mobile: 255 752 1218 67
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