Question: asking about lethargic condition of fish brooder
Answer: first check water quality of the fish pond  if acidic is found then apply lime @ 10 kg per bigha and if alkalinity is found then please consult kvk sms 
stocking density for the brooder should be 260 no. per bigha2 to 3 % 
for white spot on the gill of the fish @ dip treatment of the infected fish for 3 to 5 min in sodium chloride soln
fro pond treatment @ melichite green 0.1 mg per litre water with formaldehyde @ 25 mg per liter of wter
kvk @ 9435044574