Step #1
Start the work by drawing three ovals & line as shown.
Step #2
Draw outline for tail & fins. Also draw a line in between the body as shown.
Step #3
Make head, mouth & eye.
Step #4
Make outline for body.
Step #5
Draw tail & fins.
Step #6
Make retina & gill shape as shown.
Step #7
Make fins near the mouth.
Step #8
Draw lines over the fins and tail as shown.
Step #9
Make skin texture as shown.
Step #10
Finally, make necessary improvements to finish.