The initial volume of tank: \(40*25*30=30,000\) inches^3

The depth of 24 inches: \(40*25*24=24,000\) inches^3

If the rock, with a volume of 500cm^3, is put in, the total volume will be:\(24,000+500=24,500\) icnhes^3

We know that our aquarium is 40 inches long, and 25 inches wide, so we have to find the height, that will equal our volume of 24,500 icnhes^3.

So, \(40*25=1000\), and inches\(\frac{24500}{1000}=24.5 \). We know that our initial height was 24 inches, thus \(24.5-24=\boxed{0.5}\) inches increase.