Another Try.

 Although this print looks a bit odd, I think that once I add all the shades of orange and yellow of the original bracket fungus photo,  it might come up quite well.(see earlier photo)

Here I've tried the fish collagraph again, this time making more of a contrast between the fish and the background. I have lost some of the details on the fish, but it doesn't really matter.  As someone pointed out to me, the scales on a fish really aren't that clear when it's underwater anyway.It's only a test plate, so if I recreate it, I'll take the white 'bubble' area completely to the edges of the plate.