@Mrudul Ji, Yes most of the time it comes to the water surface with 7 to 8 mins intervals, but in afternoon the intervals extended upto 15 mins. That was cloudy, humid day with showers time to time. After 5 or 5.15 pm it never came out to the surface. The respiratory system of Eel is complex and beyond my study. It requires long and in-depth observation to understand their respiratory behavior. I have never seen a Eel in its habitat before. only I wish that I have a camera-housing for under-water photography.

@Pawan ji, I didn't see the full length of the eel as it never came out from his hide with its full body. It only protruded a part of its body from the floor of that pond as you see in images.