I have 2 ELN, both spend most of their time outside in a huge pond (the water is heated for a constant cosy temp). However, yesterday, retrieving one of my turtles for a feed, I found him laying upside down on the bottom of the tank, what appeared to be dead. Lifting him out, his body was limp with eyes closed. I dipped him back into the water to see if he was dead or unconscious, this appeared to 'wake' him up and he was gasping for air. Since then, i have kept him out of the water, warm and damp. His behaviour has returned to normal and he seems fine. This happened once before, about a year ago. There never seemed to be any sickness that followed or behaviour change. I understand they can sleep underwater...but upside down?? Is he in danger of drowning? He isn't floating so that's a no for respiratory problems, I think. He has had a few health problems before, a injured shell which lead to shell rot, infection of some sort and a lengthy dose of antibiotics. When he was very little, there was another incident with attempting to climb into the pump and appeared to lose consciousness. Otherwise, he is a very friendly turtle. They have a great diet (turtle dinner, crickets, fish, shrimp, pellets). What should I do? Without a visible symptom, I can't very well take him to the vet. But I'm worried, finding a dead looking turtle in the tank is not pleasant!! Some insight please!