My apologies for the sketchiness. But anyways, as you can see I started by making the head smaller and beafening up the body, I made the legs pretty thin as aposed to how I usually draw then, since aquatic animals doen't use their leg muscles, and those that do have them, they are very thin, pretty flat legged and long claws for gripping onto rocks and such.
I also elongated the tail and beefened it up. Most fish rely on their tails for locomotion, so they are pretty thick, as well as the fins are pretty wide to help propell the body, so I gave the webbing of the fins and bigger span of area.
There are a few things that could use some work on your wolf anatomy in general, which would include the length of the muzzle, rounded/larger ears, fur and eye placement, and of course a little work on the legs- but otherwise you defintiely are on the right track! The only other thing I would note is, proportions. Definitely something you want to consider when it comes to animals and their heads or limbs. It can be hard to work with at first, but those circles you see I sketched? It really does help with proportions and shape~
I hope this was useful. If you want, you are free to use this sketch as you like- or I can line this for you for more direct uses like coloring or adopting out.
Original Drawing/Design (c) GangnamStyle
Redline sketch (c) Geinkotsu


