Wow, what an interesting dream, Elleise. I know that you already know the meaning. But I will share my insights. This dream, as with most dreams, reflects what is going on in your waking life. I'll put the dream symbols in parentheses.
When it comes to family (reunion), there are past issues (reunion) that should be dealt with, along with a fresh start (Easter).
You are a highly emotional person (gel-like waterfall), even on a subconscious level (basement). In your waking life, you care very much about others and wish to save them from their current predicaments (trying to save the fish). To help them feels like the right thing to do, the compassionate and even Christ-like or divinely appointed thing to do (fish with white and silver streaks). You honestly believe that revealing hidden secrets will help them (bringing the fish to the surface of the water).
However, these friends/others are not as innocent as they seemed (piranhas). They will turn on you when you try to "help" them. In fact, they could attack you in such a way that you will feel powerless and you may even begin to question your abilities (attacking your thumb). They will reject your generosity (attacking your open palm).
Now, Elleise, as you know, this dream reflects your own subconscious thoughts so they could be fears or concerns rather than prophetic outcomes. But then, again, you are an intuitive so perhaps your higher self is warning you here.