pSOKOINE UNIVERSITY OF AGRICULTURE : pSOKOINE UNIVERSITY OF AGRICULTURE DEPARTMENT OF ANIMAL SCIENCE AND PRODUCTION
THE EFFECT OF WATER REPLACEMENT FREQUENCY ON GROWTH, WATER QUALITY AND SURVIVAL RATE OF NILE TILAPIA, Oreochromis niloticus AT MAGADU FARM
Name: ROWLAND FICKNARD
JUNE - 2010 INTRODUCTION : Water exchange is the process of draining part of water from the pond and then refilling the pond with clean water
Water exchange reduce the concentration of an undesired wastes (e.g.. ammonia, turbidity, pH, Dissolved organics and toxins caused by algae and fish
Large water replacement tends to
- clear natural food in water
- if its too much, pond situation will be worse due to totally removal of live food which include algae in the pond INTRODUCTION 1.0 Background information 1.2. Statement of the problem : 1.2. Statement of the problem Most farmers do not replace their pond water because they don’t know if water replacement in a fish pond is important even the rate and frequency on how many times water should be replaced is not known.
Though various studies have been carried out on water replacement the frequencies of water replacement in tank or ponds for Oreochromis niloticus was not covered,
This research therefore aimed at investigating the effects of water replacement frequencies on growth and survival rate in Oreochromis niloticus. 1.3 Objectives : 1.3 Objectives General objective
To determine the most suitable water replacement frequencies for Oreochromis niloticus in tank
To evaluate the water quality of the pond (pH, ammonia, temperature, DO etc.)
To compare the growth performance at different water replacement
To compare survival rate at different replacement 2.0. METHODOLOGY. : 2.0. METHODOLOGY. 2.1. Location of the study area
- Magadu fish tanks (S.U.A)
- Fingerlings average weight 0.48 g were obtained from Kingolwira National Hatchery Unit in Morogoro region
- The experiment done for 90 days . : . 25%H2O exchange%@) 4fish/m2…. 2.3 Water Quality Measurement : -Using chicken manure-0.5kg/pond-WeeklyTo boost natural food 2.2 Fertilization 2.3 Water Quality Measurement Temperature, pH, GH,KH,NO3,NO2 and dissolved oxygen measured
- between 0700 and 0800 hrs
- before any exchange of water
- test kits Slide 8: 2.5. Feeding of Fish
supplementary feed (maize bran)
5% body weight
At 0800 hours and 1700 hours. 2.6. Growth Measurement - Growth done by using analytical weighing balance
- Growth rate (gm/day) = Weight gain (gm) / Time (days)
- Specific Growth Rate (% body weight/day)
= N Final weight – Initial weight) x100
-Survival rate = Nt / Ni * 100
2.6 Data analysis
SPSS Table 1: Mean water quality : Table 1: Mean water quality 4.0. RESULTS AND DISCUSSION Slide 17: 4.1. Dissolved oxygen
Cause of variation!!!
-higher frequency of water added(daily water replacement)
leading to (DO)
H2O replc remove fecal matter accumulation & decomposition of excess food
- Same results obtained by (Orji et al 2006) 4.2. Nitrates and nitrites : 4.2. Nitrates and nitrites Issues behind?
-accumulation of waste(fish feces, uneaten feed &nutrients).
(Aqua check 2010) arguments!!!
high concentration of nitrate when water not replaced at all
- un-removed manure leading to:-
-So nitrate from nitrites develop
-highly H2O repl (daily ) so:-
Remove a lot of nitrates &nitrites
-so keeps the pond clean out of these nutrients.
NB/: In experiment nitrate(7.5mg/l) & nitrite(0.4mg/l) =normal range
-as fish grow 0-25mg/l and <0.5mg/l so harmless to fish (Tetra GmbH).
measures to avoid high nitrate conc
-lessening H2O repl. frequency = nitrite concentration high= up to 0mg/l conc Meck et al.(1996).
Though, it is better to replace water to remove the waste and nitrite which was slightly danger 0.4mg/lfor this experiment. in control.. 4.3 GH and KH and pH : 4.3 GH and KH and pH .
General hardness (GH)
-accumulated nutrients (calcium, magnesium, iron, zinc and other ion)
how?- (Delaying water replacement )
-so leading to increase PH value(8).
KH (Alkalinity hardness)
-lead to carbonate and bicarbonate ions accumulation
-reflects the buffering capacity of the water. (Fish doc. 2004)
Reasons for higher value in 7 days and control !!!
1-due to newly constructed tanks (cement) =so high calcium ions= raising in PH.
-due to high accumulated manure due to less water replacement
-High concentration 8.0 for the control shows the fish are in dangerous zone
Though stabilizing pH at or above 6.5,
-phytoplankton productivity increase
- increasing nutrient availability (soluble phosphate concentrations) (Warts et al 1997)
NB/: GH (>14od), KH (>20od) and PH (8 and 6.4) from normal range >4od->14od, 6od-10od and 6.5-8.5 respectively (Tetra GmbH). 4.4. Temperature : 4.4. Temperature Why variation?
So micro/ macro organisms existence = decomposition of organic mater (uneaten feeds and feces) = temperature generation (control ) not on daily replacement.
The same results by Martin, (1993)
-fish may be grown only during the warmer months
-Or if possible greenwater tank rearing may be used ()
NB/ tilapia have been shown to perform well.
low temperature in daily water replacement
-frequency water replacement
NB/: Temperature recorded at control 23.95oC were at normal range (20°C-25°C)
Daily 19oC is below Why?
-cooling of water through inflowing water which have low temperature entering the tank (Norm Meck,1996) 4.5 Growth Rates. : 4.5 Growth Rates. Slide 22: Initial weight 0.48g=final average weight (90 days)
No significance difference at P>0.05 for the 5 treatments though much increase in weight gain at the end recorded.
What is real the cause for this?
i-un-flushed natural food (phytoplankton and zooplanktons).
Ii-less disturbances set to them.
same results by Orji et al. (2006), Absalom el al (2000) and (Barreto et al, 2006),
-high growth rate observed due to less stress during water removal.
-fish do respond differently to different stressors,
- Any environmental changes add stress to the fish and the larger and faster the changes, the greater the stress. (Meck, 2000)
-daily water replacement-rapidly removal of food and other nutrients for fish to grow
-control -enough time for nutrients to build up them self.
-Generally, the lesser the frequency of water repl, the better the growth performance and survival rate of the fish Absalom el al (2000). Fig: Growth performance at different water replacement : Fig: Growth performance at different water replacement Slide 24: 4.2. Survival rate. Table 2; Survival rate (Initial number of fry / final number)*100 4.5. Specific growth rate : 100% at daily water replacement and in three days water replacement while in control, seven days water replacement and five days water replacement were 92.86%, 96.43%and 89.29% respectively (table).
-difficult to conclude the reasons for poor survival rates
-due to other factors apart from water replacement which caused fish death (fishing, wildlife predators, climatic condition) Observation!!!
>specific growth rates as < decreasing frequency of water replacement.
Reverse observation obtained by Orgi et al,2006
-The specific growth rate shows decrease on no water replacement while
He suggested that 6 days water replacement or >≠ no water replacement brought the better specific growth rate
Suggestion from this experiment
SGR increase on no water replacement while I observed no water replacement or ≥ 7 ≠ daily water repl.=better SGR
DAILY ≥ ≠ 7 days water replacement NOT GOOD FOR SGR 4.5. Specific growth rate Slide 26: Table 3. Specific Growth Rate (% body weight/day) = ((IN Final weight –IN Initial weight) x100)/T
TIME (days) =90 days Conclusion : Though to this experiment seems to be statistically no difference but it is recommended to replace water so as to overcome the problem of nitrite, nitrate accumulation
Excuse!!!!! Don’t push it back to daily please
Why? I must push
No, firstly, you may remove all the necessary nutrients
Secondly, food may be whipped away before satiation
Thirdly, fish do like peace to grow
Fourthly , Temperature variation to fish not good
weekly and above? Good!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Conclusion THANKS!!! A LOT : THANKS!!! A LOT MAY LIVING GOD
BE WITH YOU ALL