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International Journal of Aquaculture, 2014, Vol.4, No.22 1
-
6
http://ija.biopublisher.ca
5
by
EL-Shebly and Gad (2011), indicated that the fish
exposed to increased concentrations of ammonia
showed the following signs: moved very rapidly, lost
equilibrium in water, increase in their movements,
ventilation, convulsions, spiral swimming, efforts to
swallow air from the surface of water, increase in
mucous secretion in the gills and on the body surface,
hemorrhage in the gills and darkening on the skin.
Ogbonna and Chinomso (2010) reported that in order
to ascertain the cause of the death of these fishes on a
fish farm, some selected physicochemical and
microbiological parameters were used to determine
the concentration which resulted in lethal effect on the
fishes. Test results, therefore, confirmed that ammonia
concentration of above 0.20 mg L
-1
in fish ponds had a
tendency to harm the fishes. That could partly be an
explanation of why mortalities were recorded in T5
where the toxic unionized Ammonia was 0.0354 mg
L
-1
, which was closer to the lethal amount of 0.05 mg
L
-1
. That amount of ammonia equally, explained the
slow growth rate which was recorded in Treatment 5.
According to Durborow
et al
. (1997), ammonia
poisoning occurred most often when there was less or
no circulation of water in the pond. Fish size was
equally affected by ammonia. Smaller sized fish
exposed to a higher dosage per body weight unit
become more susceptible to unionized ammonia
(Piedras
et al
., 2006). Correspondingly, Cavero
et al
.
(2004) exposed young
Arapaima gigas
to a
concentration of 25 mg/L NH
3
+ NH
4
+
or 2 mg/L NH
3
for 24 hours and no effect was observed. Survival of
fish was more critical mostly during the period just
after stocking because by then the fish would have
been stressed but had to acclimatize to the new
environment. Other than handling, stress can also be
caused by the differences in temperature, which could
be worsened if the amount of toxic ammonia in the
pond was very high as observed in the present study.
In the same vein, we could not rule out the low
oxygen uptake by fish. According to Mallya and
Thorarensen (2007), it was commonly thought that if
there was not enough oxygen in the water, then the
fish would be seen gasping at the surface but this was
a last resort means to breathe. The authors reported
that the first indication there may be a dissolved
oxygen problem in the water was when the fish
become unusually lethargic and stop feeding. As
oxygen levels decrease, the fish do not have enough
energy to swim and feeding utilises yet more oxygen
(Mallya and Thorarensen, 2007).
Water quality parameters remained within the
acceptable limits for tilapia growth as described by
Boyd (1984). Most of the water quality parameters
(DO, pH and temperature) were not significantly
different in all the treatment groups except total
ammonia-nitrogen. Shepherd and Bromage (1992)
reported that carp, catfish and tilapia could withstand
Dissolved Oxygen levels of below 2 mg/L provided it
was for short periods. Lawson (1994) however,
observed that to support life for several hours, a
minimum of 1.0 mg/L was required while 1.5 mg/L
was necessary to support fish for several days. Tilapia
routinely survived dawn dissolved oxygen concentrations
of less than 0.5mg/L, considerably below the tolerance
limits for other cultured fish. The other minimum
water quality parameters reported by Lawson (1994)
were as follows: Total ammonia-nitrogen (TAN) less
than 1.0 mg/L, Nitrite-nitrogen 0.1mg/L in soft water.
The author stated that massive mortality of tilapia
occurred within a couple of days at un-ionized
ammonia >2 mg/L. Prolonged exposure to un-ionized
ammonia levels greater than 1 mg/L causes losses,
especially among fry and juveniles in water with low
DO (Lawson, 1994).
Conclusion
The study has highlighted the effects of quail manure
on growth and survival rate of the fish. The growth
rate of fish in fertilized tanks was partly attributed to
the leftover feed from the quails and the fertilization
of the water which stimulated the growth of
phytoplankton and zooplankton. Results of the
experiment showed that in order to achieve acceptable
fish growth and survival of fish, 0.48 kg quail
manure/week/2m
2
should be used as optimum for
better growth of fish, although no primary productivity
was measured to estimate zooplankton biomass in this
study. At that level, growth performance was good and
other indicators were well within acceptable range of
fish of the same size. The study further demonstrated
that higher amounts of ammonia affected growth and
survival of the fish in treatment 5 (T5), a tank with the
highest amount of quail manure added per week.
Acknowledgement
This research was as a result of efforts of many people who
despite their prior commitments devoted their time and energy