That’s good news! All of your aquarium parameters are excellent, and it’s a very good sign that your Brazilian male is eating again. He seems to be gradually recovering, and it’s encouraging that the H. barbouri and pipefish don’t seem to have been affected at all. Perhaps the crisis has passed…
Okay, keep a close eye on things for any further signs of trouble, maintain optimum water quality, and be prepared to perform a major water change if necessary. Between the purigen, activated carbon, and Poly-Filter pad, any contaminants or toxins that may have been present in the water should have been removed and hopefully all will be well from here on out.
Best wishes with all of your fishes, Barbara!