1. Water Quality inWater Quality in
AquacultureAquaculture
DR BENEDICT MUYIWADR BENEDICT MUYIWA
MD/CEO OCEANBLUE AFRIQUE CONSULTING LIMITEDMD/CEO OCEANBLUE AFRIQUE CONSULTING LIMITED
Email:roti2571@yahoo.comEmail:roti2571@yahoo.com
2. To a great extent waterTo a great extent water
quality determines thequality determines the
success or failure of asuccess or failure of a
fish farming operation.fish farming operation.
3. TopicsTopics
• Water CharacteristicsWater Characteristics
• Water SourcesWater Sources
• Water Balance in FishWater Balance in Fish
• Chemicals and their parametersChemicals and their parameters
• StratificationStratification
4. • EatEat
• BreatheBreathe
• Excrete wastesExcrete wastes
• ReproduceReproduce
• Take in and lose saltsTake in and lose salts
Fish perform all bodilyFish perform all bodily
functions in waterfunctions in water
5. Physical CharacteristicsPhysical Characteristics
of Waterof Water
• Absorbs heat wellAbsorbs heat well
• The "Universal Solvent" (50% ofThe "Universal Solvent" (50% of
known chemicals found in naturalknown chemicals found in natural
waters)waters)
• The densest around 4The densest around 4 oo
CC
6. Water SourcesWater Sources
• Wells and springsWells and springs
• GroundwaterGroundwater
• Streams, rivers and lakesStreams, rivers and lakes
• MunicipalMunicipal
7. WellsWells
• AdvantagesAdvantages
–Usually constant temperatureUsually constant temperature
–Usually free of wild fish and insectsUsually free of wild fish and insects
• DisadvantagesDisadvantages
–Will require pumping unless artesianWill require pumping unless artesian
–May have high levels of COMay have high levels of CO22
8. SpringsSprings
• AdvantagesAdvantages
–No pumping costsNo pumping costs
–Relatively stable temperatureRelatively stable temperature
• DisadvantagesDisadvantages
–Flow rates may vary with seasonFlow rates may vary with season
–Insects or fish may inhabitInsects or fish may inhabit
10. Streams, Rivers & LakesStreams, Rivers & Lakes
• AdvantagesAdvantages
–Large quantities may be availableLarge quantities may be available
• DisadvantagesDisadvantages
–Temperature varies widelyTemperature varies widely
–Excess nutrients may be presentExcess nutrients may be present
–Unwanted fish and insectsUnwanted fish and insects
–Quality is questionableQuality is questionable
18. 0.8
0.6
0.4
0.2
0.0
2 6 10 14 18 22
8
6
4
2
0
Ammonia
(mg/l)
Nitrites &
Nitrates
(mg/l)
NH
NO
NO
2
3
3
Time in Days
Time Required
for Bio-Filter to Mature
19. PhysicalPhysical
PropertiesProperties
Species % volume % mass Molecular Wt.Species % volume % mass Molecular Wt.
Nitrogen 78.084 75.6 28.0Nitrogen 78.084 75.6 28.0
Oxygen 20.946 23.2 32.0Oxygen 20.946 23.2 32.0
COCO22 0.032 0.048 44.00.032 0.048 44.0
Aragon 0.934 1.3 39.9Aragon 0.934 1.3 39.9
Air 100.00 100 29.0Air 100.00 100 29.0
Gas Solubility in Air (15Gas Solubility in Air (15oo
C) Solubility of pure gas (15C) Solubility of pure gas (15oo
C)C)
Species ( mg/l) (mg/l)Species ( mg/l) (mg/l)
Oxygen 10.08 48.14Oxygen 10.08 48.14
Nitrogen 16.36 20.95Nitrogen 16.36 20.95
Aragon 0.62 65.94Aragon 0.62 65.94
COCO22 0.69 1992.00.69 1992.0
Dry Air Components
Solubility of Four Major Gases in water
20. 100
50
0
4 5 6 7 8 9 10 11 12
Free CO HCO CO
Percent of Total CO2
3
- =
2 3
pH
Effects of pH on Various Buffers
22. Percent of Total AmmoniaPercent of Total Ammonia
in the Un-Ionized Form atin the Un-Ionized Form at
Various Temperatures and pHVarious Temperatures and pH
percent Ammoniapercent Ammonia
Temperature (Temperature (oo
C)C) (pH) 7.0 8.0(pH) 7.0 8.0 9.09.0
1010oo
0.19 1.83 15.70.19 1.83 15.7
2020oo
0.400.40 3.823.82 28.428.4
3030oo
0.800.80 7.467.46 44.644.6
23. Breakdown of AmmoniaBreakdown of Ammonia
Excreted into Water by FishExcreted into Water by Fish
Ammonia (NH ) Nitrites (NO ) Nitrates (NO )
Nitrozomonas Nitrobacter
3
1½ O2 1½ O2
2 3
25. Total Alkalinity Lime/Surface Area (ha)
12 -12 - mg/lmg/l 1 ton1 ton
12 - 14 mg/l12 - 14 mg/l 3/4 ton3/4 ton
15 - 25 mg/l 1/4 - 1/2 ton15 - 25 mg/l 1/4 - 1/2 ton
25 mg/l or more25 mg/l or more NoneNone
Guidelines forGuidelines for
Application of LimeApplication of Lime
35. Color and Appearance ofColor and Appearance of
WaterWater
Secchi disk readingSecchi disk reading
(cm)(cm) CommentsComments
Less than 20Less than 20 Pond too turbid. If pond is turbid with phytoplanktonPond too turbid. If pond is turbid with phytoplankton
There will be problems with low DOThere will be problems with low DO22 concentrations.concentrations.
When turbidity is from suspended soil particles,When turbidity is from suspended soil particles,
productivity will be low.productivity will be low.
20 – 3020 – 30 Turbidity becoming excessive.Turbidity becoming excessive.
30 – 4530 – 45 If turbidity is from phytoplankton, pond is in a goodIf turbidity is from phytoplankton, pond is in a good
condition.condition.
45 – 6045 – 60 Phytoplankton becoming scarce.Phytoplankton becoming scarce.
More than 60More than 60 Water is too clear. Inadequate productivity andWater is too clear. Inadequate productivity and
danger of aquatic weed problem.danger of aquatic weed problem.
36. Effect of pH on warm water pond fishEffect of pH on warm water pond fish
4
5
6
7
8
9
10
11
pH
Acid death point
No reproduction
Desirable range of fish production
Alkaline death point
Slow growth
37. Effects of DOEffects of DO22 concentration on warm waterconcentration on warm water
pond fishpond fish
0.0
0.3
1.0
2.0
3.0
4.0
5.0
DissolvedO2,(mg/l)
Small fish survive short exposure
Lethal if exposure prolonged
Fish survive, but growth slow
For prolonged exposure
Desirable range
