Asian Swamp Eels

[Econza]

Hi all,
Looking for some insight into Monopterus Albus behaviour. I have three leucistic eels and have had them for about three months. Recently (last two days) they have been sticking their heads out the water of the tank. I changed the water a week ago and did not do anything different from normal. Has anyone else seen this behaviour or have some insight?
Thanks.

 

[Shaihulud]

Mine oes it all the time, from young to fully grown 3ft adult. I almost never change water, topping up when the water level gets low. Mine will stick its head all the way up into the air when I put my hand above the tank.