Wakkanai Aquarium

Japanese Huchen Parahucho perryi, Bering Wolffish Anarichias orientalis, one of the atka mackerel species Pleurogrammus sp., at least two rockfish species Sebastes sp., and I'm not sure what that flatfish is.

@DaLilFishie
Paralichthys olivaceus?

Looking at the image @Chlidonias posted of the signage, I'd say it's most likely a Stone Flounder Platichthys bicoloratus

I took photos of all the signage on the tanks (it was very complete, unlike many aquariums!), but of course it was all in Japanese and most tanks did not include scientific names - I just haven't had time to go through and try to identify everything yet.

I've worked through all the signage in the Aquarium.

This tank contains:

Sakhalin Taimen / Japanese Huchen Parahucho perryi (Hucho perryi)
Bering Wolf-fish Anarichias orientalis
Barfin Flounder Verasper moseri
Starry Flounder Platichthys stellatus
Stone Flounder Platichthys bicoloratus
Slime Flounder Microstomus achne
Black Rockfish Sebastes schlegelii
Three-striped Rockfish Sebastes trivittatus
White-edged Rockfish Sebastes taczanowskii
Okhotsk Atka Mackerel Pleurogrammus azonus
Fat Greenling Hexagrammos otakii
Rock Greenling Hexagrammos lagocephalus