Observation

 

 

In part (a), majority of the candidates could not mention instruments for measuring the water quality parameters. They could not distinguish between pH scale and pH meter.

In part (b), majority of the candidates could not accurately give the optimum ranges for dissolved oxygen, temperature, turbidity and pH.

In part (c), majority of the candidates could not correctly define a fish pond.

In part (d), this question was popular among the candidates. Majority of the candidates stated the features of intensive and extensive system.

The expected answers include:

(a)        Instruments for measuring water quality parameters

            (i)         Dissolved oxygen

                        Dissolved oxygen (D.O.) meter

            (ii)        Temperature

                        Thermometer

 

            (iii)       Turbidity

                        -           Secchi disc
-           Turbidometer

            (iv)       pH

                        pH meter

(b)        Optimum ranges for water quality parameters for fish culture

            (i)         Dissolved oxygen

                        5 – 8ppt or 5-8 mg/l

            (ii)        Temperature

                        25oC – 32oC

            (iii)       Turbidity

                         30 - 60  cm

            (iv)       pH

                        6.5 – 8.0

(c)        Description of fish pond

It is an enclosed water body specifically for growing fish or other aquatic animals under controlled conditions. It has inlet and outlet

(d)        Features of management systems in aquaculture

            (i)         Intensive system

-           fish are stocked at a high stocking density
-           fish are fed exclusively on a balanced diet
-           it is capital intensive
-           it is usually monoculture
-           high yield / output
-           regular monitoring
-           requires specialized skills
-           proper record keeping
-           labour intensive
-           proper disease control

(ii)        Extensive system

-           low stocking density
-           low productivity
-           low level of investment
-           fish depend mainly on natural food
-           poor yield
-           poor or no disease control
-           poor record keeping

  -           usually polyculture