Ion-fab-button custom close icon

Hi! With this code i was able to put a custom image on the ion-fab-button

<ion-fab >
      <ion-img src="/assets/open.png"></ion-img>

but when the list is opened the default close icon (x) is still visible and I can’t put a custom one.
Is it possible to use a custom png instead of the close icon, without the animation?
The image is a circle of the same dimensions of the button.