Do I need to add “da” before “to iimashita”?

Question

Not sure how to say "my mum said it was fun." Is this correct:

watashi no okaasan wa, sore ga tanoshi to iimashita

Or do I need to add "da"? As this is for speaking.

Answer 1

I would like to add a clarification to user4092's answer:

In English, present tense verbs are changed to past tense in reported speech.

"My mum said it was fun" would mean that she said she had fun as the activity was going on. If this is what you meant, then the Japanese sentence below is the answer:

English direct speech: My mum said, "This is fun!"

English reported speech: My mum said it was fun.

Japanese reported speech: watashi no haha wa tanoshii to iimashita

"My mum said it had been fun" would mean the mother said she had fun after the activity was over. If this is what you meant, then the Japanese sentence below is the answer:

English direct speech: My mum said, "That was fun!"

English reported speech: My mum said it had been fun.

Japanese reported speech: watashi no haha wa tanoshikatta to iimashita

Please note:

1. tanoshii conjugates to tanoshikatta (for i-adjectives, drop the last i and add katta)

2. Change iimashita to itta for plain form. (As in user4092's answer.)

3. I would also like to point out that tanoshii in your original sentence is missing an i.

4. Add da when an indirect quote ends with a na-adjective or noun...

watashi no haha wa kirei da to iimashita (My mum said it was beautiful.)

watashi no haha wa hana da to iimashita (My mum said it was a flower / they were flowers.)

...but not when an indirect quote ends with an i-adjective or verb:

watashi no haha wa tanoshii to iimashita (My mum said it was fun.)

watashi no haha wa ashita iku to iimashita (My mum said she would go the next day.)

Answer 2

No, you don't need it. But you should translate "my mom" to "(watashi-no) haha" and "it was fun" to "tanoshikatta", as a whole "(watashi-no) haha-wa tanoshikatta-to itta".