D.     PRACTICAL TEST - DETERMINING FEED RATIO


In this activity, you will weigh fish and determine biomass in order to formulate a proper feed ration. Because feed is a high cost, it is important not to overfeed. Fish have a tendency to gorge themselves when overfed, causing a fatty fish. Also, excess feed in the system degrades water quality as the feed decays.  Additionally,  underfeeding will increase the length of production time. Care must be taken to produce a quality product with minimum costs.


STEP I - Fill a four liter beaker about half way with water and weigh it using the balance.  Use the tare function on the electronic balance. If you use the triple beam balance, remember, to use the counter weights. (You must add them to get to the total weight.)

STEP 2 - Carefully remove 3 fish from a tank and place them in water. Record the new weight.

STEP 3 - Return fish to water

STEP 4 - Determine the average weight.   Multiply by the number of fish in the tank. This will be provided. Determine how much feed is needed per day at a 2% per day feeding level.

There is 50 points possible for this practicum (5 points for each step performed correctly and 25 points for the correct answer.) The breakdown is as follows:

Steps 1-4 performed correctly for up to 20 points.
Formula used correctly for 5 points.
Correct answer for 25 points.