I agree that you did a nice job on the drawing. I like that the lines are clean all througout the drawin. I also love the idea :P. What Polyvios Animations suggests is true, you should add the Horizon line. Because at the moment it almost looks like an isometric drawing. That means that you understand the 3d form of your mech, which is already awesome. Because you understand its 3d form, you've drawn all lines which are parallel in 3d also parallel in the drawnig. This is as I've said already a good starting point, as this is basically the rule to follow isometric Perspective.
However, isometric drawings are good for character designs sheets or construction plans, because the proportions are more obvious, but if you want to go for an illustration that uses camera perspective, you should try to go further an work with a horizon line and 2 point perspective.
If you just want feedback on your Forms so you can focus on the Design, thats fine too, your Line Art is already good enough to continue with the design process.
edited this post on February 6, 2020 2:30pm.
I made you an example with a horizon line. I put the line on the height of the fish's eyelevel so we can identify better with the fish. If it were above the fishes eye level the fish would be looking down on us making him more threatening. If the Horizon level was below his eye level he would seem smaller.
In general the perspective on the mech seems very solid and the design is very clear, albeit blocky. The only thing is that it doesn't seem like your fish character in the mech suit is totally solid yet. I'd work on him a bit.