I woke up this morning to find my RTS laying on his side at the bottom of the tank. I thought he was dead until I tried to net him. But swam away into a cave and is laying on his side breathing very slowly. Now I never see my shark go for any kind of food so I'm not sure what happened. I did leave an algae wafer in there when I turned the lights out for my 4 cories and my khuli could it be that my shark ate too much?
The thing is when I had my shark in his own tank he barely ate anything he only nibbled it a bit because he's only a baby.
Any advice. I'd hate to see this guy go

. Also note that I bought this little guy from a really poorly taken care of tank and he was in bad condition. This was about a month and a half ago
Water Parameters are
pH 8.0
Ammonia 0
Nitrite 0
Nitrate 10
Temp 76 F
29 Gallon 30 Long 18 High 12 Wide.
This sucks because I have to go to work in about a half an hour.