Speckled sanddab, Citharichthys stigmaeus
ID thanks to Greg Jensen
God's Pocket Bay, Hurst Island, British Columbia
Thanks to Milton Love and Julie Passarelli for their comments about the fish and its parasites.
Comments by Milton Love:
"It is either the speckled sanddab, C. stigmaeus or the Pacific sanddab, C. sordidus. Both species live in that area. Unfortunately, both species are capable of changing patterns depending on the substrate they find themselves in, so that is not much help.
The usual way of identifying them is 1) to see if there is a ridge between the eyes (no in C. stigmaeus), but that is hard from a photo. The other way is to see if, when you metaphorically flip the pectoral fin over (towards the head) the tip of that fin extends at least to the center of the eye (i.e., C. stigmaeus has a shorter pectoral fin, proportionately). When I do that on the screen it seems that the pectoral fin does extend to the center of the eye, but I would not bank on that.
Julie Passarelli at the Cabrillo Marine Aquarium confirms that the parasites on this fish are leeches. Since there are no records of leeches on sanddabs, this may be new to science."