# Symbol in energy formula vs amplitude

Can someone tell me what does the symbol mean in the formula for energy compared to amplitude? Looks like a partial infinity sign, almost like a fish symbol.

As stated in the comment, the "fish" is the mathematical symbol for "proportional to". In the case of the amplitude and energy, $$E\propto A^2$$ means that $$E=CA^2$$ for some constant $C$.
It seems that "fish" refers to $\propto$. It is means "proportional to". Since @Kyle Kanos has provided useful links about this, I won't repeat them.