I have a 90 gallon freshwater aquarium. Yesterday I noticed that one of my angels wasn't eating. She was very lethargic. This morning she had passed away. My other angel is looking for her and is flicking her feeler fins almost as if she is confused. I only had 2 of them. Will my other fish be ok by herself for a couple weeks? I know it's a weird thing to wonder about, but my angels were inseparable.