Yes, that's a fish-head. One of several freaks of nature to come, I hope. I came up with the image of the ballooning cats initially, and it seemed to me like the work of a fish bent on revenge.

I knew it was a fish head immediately because cartooned sharks have sharp triangle pointed teeth.

Things are getting interesting. These last few pages have grown more gorgeous one after the other. You make it seem you really like rendering stuff with those line hatchings.