Yeah, the English to German translation of "That reminds me.." usually won't do, if grammatically and stylistically correct German is your goal.
That said, most people would probably get what you're trying to say if you used it that way.
The correct translation/phrase in this context would probably be:
"Ach ja! Wo wir grade davon sprechen: (...)"
"Wo wir grad dabei sind - (...)"
If it actually is used in the context that something reminds you of an event, some story, or thing in the past, then you would say something like: "Dabei muss ich immer daran denken, wie (...)"
This is only used when something actually reminds you of someone or an occurrance in the past. It is not used for e.g.: "That reminds me-I have to pick up the kids from school" ;)