The main thing about interpreting dreams is not to get hung up on other people's interpretations and not to look for deep meaning in every image :) A dream dictionary will say one thing, a psychologist will say another, and your subconscious might just be replaying recent impressions. You shouldn't make serious decisions based on a dream or expect miracles in the coming days.
But there's actually an interesting point here - clear water and active fish usually associate with clarity and positivity. If you add context (have you been stressed lately, or on the contrary relaxed, maybe thinking about some goals), the picture becomes clearer. Dreams like this often come when your head is clear and you're not hung up on problems. It's more of a reflection of your state than a prediction.
The key thing is not to look for a universal answer in dream dictionaries - they're the same for everyone anyway, but dreams are different for each person. Your lake with fish might mean something completely different from another person's lake dream. Trust your gut: if the dream left a pleasant impression, then that's already good 😊