The objective of the present study was to evaluate the
rearing of Pomacentrus caeruleus at lower salinities and further
determine the condition factor (K) and growth rate under artificial
Materials and Methods
Fish belonging to the species Pomacentrus caeruleus were
procured from Rameshwaram and Chennai, through ornamental
fish traders. They were placed in polythene bags filled with sufficient
air and transported to Bangalore. Fishes, 120 in number were
quarantined and transferred to glass aquaria (2x1x2 ft) with a 60 l
water holding capacity. The aquaria were fitted with under water
biological filters and thermostat for maintaining water temperature.
Artificial sea water was made by dissolving 25 g of commercial sea
salt in 975 ml of water (25ppt), mixed thoroughly, allowed to settle
and then aerated for 48 hrs before use
Acclimatization at different temperatures to lower salinities :
Fish were divided into three groups of 24 each. Group 1 was used
for acclimatization at 20ºC, group 2 at 25ºC and group 3 at 30ÚC.
Initial salinity was maintained at 25 ppt. Fish belonging to each
group were divided further into four groups of 6 each based on
their length. Initial length (Total length) and weight was recorded
before the start of acclimatization process. Fish were then subjected
to the process of acclimatization to lower salinities by gradual
decrease in salt concentration. The length, weight and the body
width was recorded at 20, 15, 10 and 5ppt of salt concentration.
The temperature of water was maintained constant throughout the
experiment (48 days) and once in 2 days 30% water was changed.
Fishes were fed with boiled beef (minced heart meat) twice a day
i.e. morning and evening. Water salinity was measured using a
refractometer. pH and dissolved oxygen (DO) was maintained at
7.8-8.2 and 4.5-5.0 respectively.
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- 7 年前最佳解答