So I had 2 female bettas in separate tanks (1 gallon each) and I just changed their water and barely an hour later one was dead. I just noticed that the other is dead also! I have no idea what went wrong, it's the strangest thing. I treated their water, but I think I may have added too much aquarium salt, would that kill them so quickly? It wasn't like a massive overdose. I maybe put in 1/3 tsp instead of 1/4. Any thoughts??