Observation

This question was fairly attempted by the candidates. Although, most of the candidates were able to state an observable difference between specimens A (Fish pond water) and B (Tap water) with reason as required in 1(a-b), majority of them were unable to state with reason which of specimens A (Fish pond water) and B (Tap water) is more suitable for the culture of table fish as required in 1(c-d). Also, in 1(e), most of the candidates could not describe the ways of improving the quality of specimen B (Tap water) for table fish production.

The expected answers were:

 1(c)     Specimen more suitable for the culture of table fish

Specimen A (Fish pond water).                                                                                 

  (d)     Reasons for the answer in 1(c)

-   It has natural fish food/nutritious/rich in nutrients/has fish food/has plankton
-   Presence of plankton improves oxygenation/presence of plankton improves
aeration/aerates the water/adds oxygen to water.
-    Presence of plankton increases productivity in fish pond water.
-    It provides good environment for fish culture/good culture medium for fish.

(e)      Ways to improve quality of specimen B (Tap water) for table fish   
          production

Application of fertilizer/inorganic fertilizer/organic fertilizer/manure  
-   Could be broadcast/spread/bagged in the water.
-   It increases nutrient content/improves plankton growth/increase fish food.
-   Increases primary productivity of pond.                           

Liming/application of lime ( It could be done before or after impounding)         
-   Creates a suitable pH for growth of fish.
-   Liberates nutrient.
-   Keeps the water free of pathogens/parasites.
-   Creates suitable environment for fish food to grow.               

Aeration/addition of oxygen/oxygenation                                                             
-   Increases dissolved oxygen which improves the quality of water.
-  It could be done by using aerator/ splashing the water surface with stick/paddling.                                                                         
Inoculation / Addition / introduction of plankton /algae /zooplankton / microphytes / phytoplankton                                                                                  

-   If conditions are favourable, these planktons will flourish thereby improving the
quality of water.                                                                     

Dechlorination/ removal of chemical (chlorine)                                 
-   Leave water for chlorine/chemical to escape/expose water in the open air.
-   Stir continuously for chlorine/chemical to escape.
-   Delay stocking.                                                                      

Exposure to sunlight                                                                                    
-   Wind will blow algae spores into the water which will then grow and spread in     
the water.
-   Oxygen will dissolve into the water.
-   Other fish food organisms will be attracted into the water.