it hasn't updated to show the minnow icon, it still shows a redfish

This is because of the image cache implemented by Steemit. To bypass it, one simple trick is to add a parameter at the end of your url, like the current date

example:

https://steemitimages.com/100x80/http://steemitboard.com/@phoenixwren/level.png?20181027

will display it correctly: