Tilapia culture in trinidad and tobago: yet another update


The Objectives of the experiment were as follows



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The Objectives of the experiment were as follows:

  1. To determine the effects of plankton on growth rates of tilapia.

  2. To compare the differences between organic fertilizers (cow manure) and inorganic fertilizers (Triple Super Phosphate (TSP) and urea) on phytoplankton “bloom”

  3. What causes phytoplankton bloom to “crash or die off”

Materials used in the experiments are:

Four tanks each measuring 7.3 m.

Triple Super Phosphate (TSP)

Urea

Cow manure



1 Secchi disk

Agricultural lime

Biological microscope


Slides

Digital camera

pH meter

DO meter


Temperature meter

40 fishes, 10 fish per tank




Procedure used for conducting the experiment:

  1. The tanks 1, 2, 3 and 4 at the SatyadeowSawh Aquaculture were treated with agriculture lime to kill any unwanted fish and increase the pH of the water.

  2. Water sample was collected from the concrete ponds, using a microscope the samples were examine to identify the algae present; chlorella was isolated and culture in the lab. It was then used to inoculate the selective tanks.

  3. Tank 1 was not fertilized nor inoculated with chlorella, tank 2 was fertilized with cow manure (0.14g/m2) and inoculated with chlorella, tank 3 was fertilized with TSP (0.014g/m2) and Urea (0.014g/m2) not inoculated with chlorella, while tank 4 was fertilized with cow manure (0.14g/m2), TSP (0.014g/m2) and Urea (0.014g/m2) and inoculated with chlorella.

  4. Ten fishes between 20 – 25g were placed into each tank.

  5. Every two weeks they were weighted and the figures recorded

  6. The transparency of the water was checked twice weekly (Tuesday and Friday) using a secchi disc to monitor the fertilization process.

  7. The pH meter was used to check the pH daily (morning at 9 hrs and afternoon at 15 hrs).

  8. The DO meter was used to check the dissolved oxygen level daily (morning at 9 hrs and afternoon at 15 hrs).

  9. The thermometer was used to check the temperature of the water daily (morning at 9 hrs and afternoon at 15 hrs).

  10. Water samples were collected once a week and observed under the microscope.

  11. Water exchange was conducted on Mondays and Fridays or as a need arise.

Results




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