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Research Journal of the University of Ruhuna, Sri Lanka- Rohana 13, 2021
soya bean, coconut meal and wheat flour were measured using a Kjeldahl Analyzer;

Model VELP Scientific UDK 139.

Protein level of 40% was selected to formulate test diets and the control diet.

Control diet with 40% protein was prepared using fish meal, soya bean, coconut
meal, wheat flour and other diet formulating ingredients. From the weight, 35% of

control diet was substituted with medicinal plant ingredient to formulate the test

diets. The diets were made into a form of strings using a string hoppers making
machine having a perforated diameter of nearly 2.5 mm. Dried pellets were broken

manually into very small pieces depending on the size of the experimental fish. All
o
the dried pellets were packed in polyethylene bags and stored in a refrigerator at 4 C
until they were used in the experiment. Fish were fed approximately 5% of their
body weight twice a day for 3 months period.

Weight and length measurements were taken every fourteen days. After first two
weeks, length measurements were taken for randomly selected 15 fish. Condition

factor for each fish was calculated. Tanks were cleaned by siphoning out faecal
matter and uneaten feeds once in two weeks.

The following indices were used to determine growth performance of fish.

Relative Growth Rate = Weight (g) or Length Increment during the time interval

(cm) / Initial Weight (g) or Length (cm)

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Condition factor = [W/ L ] x 100

[Where: W = Weight increment of fish (g); L = Length increment of fish (cm)]

Water Quality Measurements

Physicochemical parameters pH, conductivity, temperature, Dissolved Oxygen
(DO), Biological Oxygen Demand (BOD5), nitrate and ortho-phosphate

concentrations were measured once in two weeks.

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