this is the 4"er right?
my tsn X rtc did the same thing to me when i first got them. turn off the lights when you feed him. mine still only eat at night and they are about 7" now and they were 2" when i got them about 2 months ago
try blackworms, night crawlers, krill, brine shrimp, and cut up market shrimp. i have never feed them fruit.
im my opinion worms are the way to go as they do not pass disease's and are all protien. they will beff up your little buddy in no time.
my 2 Tsn aren't eating fine too, so I started to force feed them, opening their mouths and putting some feeders in.
So I decided to move them to an inside tank, them they start eating the feeders in there.
Try some blackworms as themancmt said.