What is the molar concentration of the naoh solution

0.397g/204=0.00194608mol this is the moles of the potassium hydrogen phthalate. Assuming the reaction ratio is 1:1 this is the same number of moles for the sodium hydroxide. we now use the solution triangle rearranged to find concentration. Moles/volume=concentration 
0.00194608mol/16.22ml/1000(to convert to decimeters cubed) 
Final answer is 0.00000012M-1.2x10-7

I’d have to say no because without oxygen in the water the fish would all be dead. so if you want to fish for dead fish, pick the ponds with the lowest oxygen concentrations.