hi...I am really really extremely sad because all of my turtles but one suddenly died...they were soft shell turtles and i got them like a month ago...i think it is too late to save the last one because she looks pretty sick but i want to know if someone can tell my why they died because i feel so guilty because i feel like i killed them :'(... they were babies, like 5 cm diameter, they were in a 40 L tank, it was full of water and i put two islands on the surface so they could rest, it has sand on the bottom because they like to bury themselves and a filter... at the beginning they were fine, all energetic and eating...suddenly out of nowhere one of them died, and i was really sad but i thought maybe she was already sick or she didnt make it because she was the smallest one. (realy tiny). then another one died and i got really worried and i removed some artificial plants i had put because i thought maybe they were infected or something...i put salt, an anti-chlorine and another thing i bought that supposedly is for turtle aquariums, to kill bacteria...after a while all of them appeared to have hair, like cotton...i read it was fungus and i should treat it giving them more dry land and i bought medicine and put drops on them and suddenly they stopped eating and then they died only one is left, but she seems to be very sick..she doesn't have hairs anymore but she stays all the time on the island when they were used to swimming and burying themselves. can someone tell me why they died? what did i miss ?