Experimental site and pond preparation
The experiment was conducted at the Fisheries Field Laboratory of the Faculty of Fisheries, Bangladesh
Agricultural University (BAU), Mymensingh, Bangladesh. The field trial was carried out for a period of 120
days from 16 October, 2006 to 12 February, 2007. Nine earthen ponds each having an area of 80m
2
and
an average depth of 1.5m were used for this experiment. The ponds were rectangular in shape, equal in
size, depth, basin configuration, bottom types and contour and fully exposed to prevailing sunlight and
were previously used for research. The main sources of water of the ponds were rainfall and deep tubewell. Before starting the experiment, ponds were renovated and cleaned of aquatic vegetation. All
unwanted fishes and other larger aquatic organisms were eradicated by application of rotenone at the
rate of 2.5g m
-3
. Open ponds stocked with Climbing Perch were fenced by 1m height nylon net and
bamboo poles. Lime (CaCO3) was applied to the pond water at the rate of 250kg ha
-1
. One week after
liming, the ponds were filled with water from adjacent deep tube-well. Then the ponds were fertilized with
cattle manure, urea and TSP at the rate of 1000, 50 and 50kg ha
-1
, respectively.
Cage construction and suspension
Six cages were constructed each with size of 1m
3
(1m×1m×1m). The cages were square shaped, made
of iron frame and covered by black nylon net with tied nylon twine. The mesh size was small enough
(8mm to15mm) not to allow the experimental fish fry escape and large amount of water can easily pass
through the cages. One edge of upper side of eachcage was kept open and tied with nylon threads for
management practice. One cage was installed in each Caged Perch and Caged Tilapia pond with the
help of one horizontal and two vertical bamboo poles before stocking. The cages were installed at 15cm
above the pond bottom at the middle of each pond giving a water volume of 0.85m
3
. The cages were tied
fixed with bamboo frame by nylon ropes. Bamboo made platforms between pond banks and cages was
used for easy feed supply and observation of the cages.