How to change SVG hover colour using HTML and CSS?

I’m trying to implement an SVG file in my WordPress footer that changes colour when the mouse is hovering on it.

In my WordPress footer file:

<a href="LINK"><img src="SVG NORMAL" class="apple" width="36" height="36"onmouseover="this.src='SVG HOVER"'" onmouseout="this.src='SVG NORMAL"'" /></a>

In my CSS:

.apple:hover {
   fill:#707070
}

Thanks for the help.