Make sure that the turtles can get out of the water in some uva/uvb light (sun light) or they will get a disese called soft shell and they will eventually die. They could also get shellrot.

If you see a turtle caught underwater and appears to have drownd. Put him on dry land NOT UPSIDE DOWN and pump his legs, to try to get him to breathe again. Some people have reported this to work if the turtle is caught quick enough.

 If Turtle is vocalizing, either by loud breathing or clicking sounds, appears to be gasping for breath, swimming lopsided, or is has mucus or foam at the mouth or nose, the turtle is probably suffering from a respiratory infection. This is very deadly in turtles. In addition to the above measures, it is IMPERATIVE the turtle be brought to a reptile vet (see link below) to get antibiotics. Most untreated turtles who have respiratory infections will die. For more information read: http://www.tortoise.org/archives/brown1.html http://www.tortoise.org/general/urds.html http://www.tortoise.org/general/urds2.html

Turtle’s shell appears to have air pockets under the scutes, and some are falling off. For a picture, see http://www.geocities.com/sassi49575/photop...pagespiral.html .
If there are scutes underneath, your turtle is shedding and growing. This is a sign of health, not sickness. DO NOT pull the scutes off. As the new scute becomes fully formed, the old scute is released. If you pull the scute off before the new scute is fully formed, your turtle may have exposed bone, and this is difficult and complex to treat, and leaves the turtle subject to disease and death.

 A way to heal a turtle that has fungus, or shell rot is. Salt soaks for a few minutes each day, and drydocking, with lots of direct sunlight, but not to the point where the turtle gets severely dehydrated. If fungus gets advanced, it will kill your turtle. Here is a pretty good thread about fungus: http://www.turtletimes.com/forums/topic.as...?TOPIC_ID=12802 .

If turtle won’t eat This is normal for a few days in a new environment. If this is not a new turtle in a new environment, try: Favorite foods. If unknown, try sardines, strawberries, live bugs, reptimin. For more good nutritional foods read:
http://www.chelonia.org/Articles/nutrientanalysis.htm and for poisons to avoid read http://www.chelonia.org/Articles/plantsthatpoison.htm . Regular day and night cycles, with a day period of not less than 14 hours. To make sure he can get unintterupted sleep, if you keep him in an area heaviy traveled at night, cover his tank with a dry but dark cloth.
Raise temperatures to sick turtle levels. Get vitamins into him, by leaving them in his water, if necessary.

If a turtle cannot eat due to serious illness or injury, a vet can tube feed the turtle. Here is a post which shows, graphically, how it is done. DO NOT TRY THIS AT HOME! Leave it to a vet, vet's trained assistant, or a qualified wildlife rehabber. If the tube goes into the lung, the turtle will be killed when you force food into his lung! I repeat: DO NOT TRY THIS AT HOME! http://www.turtletimes.com/Forums/topic.as...?TOPIC_ID=20744