Effect of low density to fish

[ivan1407]

Due to not checking the water density for several weeks it had dropped to 1.021. During that time a number of fishes started heavy breathing before they died. Is there a direct link between the low density for at least two weeks and the fish mortality?

[arizona tech]

if it droped to 1.021 that is not a problem, your fish dieing is, how long has the tank been up and running, have you checked your water parmeters recently, i run my fo only tank at 1.020 and have no problems

[ivan1407]

pH 7.8 - 8.1
temp 23 - 25 °C (sorry for the EU standard)
nitrate 0.2
phosphate 0.09

The tank is operational for two years now