You can say: That fruit is off [ covers all ways that fruit is spoilt] OR That fruit is not fresh Usually oranges go mouldy when they are not fresh As a question: Is that fruit still fresh/ Is that fruit off? Are those oranges mouldy?

Normally, you would say "rotten".

Completely agree with fdmaxey. Also, to correct your question, it should be "How do I say that a fruit is not good ? Should it be "The orange was spoiled" or "The Orange was spoilt"?

'Spoiled' and 'spoilt' are both the past tense of 'spoil' 'Spoilt' is used more in England and Ireland. In the U.S. has been replaced over the years with 'spoiled'. Both are undestood in all English-speaking countries.