It was too late

I was putting water in my freshwater tank and added aquarium salt to the mix. I had water left over and decided to top off my brackish tank with it. I forgot I put aquarium salt in the mix and went ahead and added marine salt to the water I had left over. Mixed it and poured it in my brackish tank. Did I mess up? Is aquarium salt n marine salt mix bad for my brackish tank. I poured about half a gallon of it

 

Don't think at that amount would cause issues. I always used marine salt mix & just mixed it to the sg that my brackish fish needed.

 

Oh no. I just woke up. My puffer fish is laying down. I think I did mess up. Idk what to do. Except a water change.

His eyes are cloudy too looks darker skin. His a figure 8

 

Yes he is showing signs of stress.What do you keep the sg at? A water change via a drip to slowly bring it up or down . I have only kept scats & gobies, Hopefully someone with figure 8 puffers will chime in.

 

I did a 75% water change. Right after i posted last. Currently he looks to be doing better. More actively swimming. I think i saved him. I was freaking out badly, looked like he was choking. Scariest sight ever