This is the backstory. If you want to skip to my question it is in bold. I have to admit I accidentally did something really stupid. One of my sorority members died in her quarantine this morning. None of the girls had contact with each other, but the girl in question has been totally erratic and agitated since the day I got her. I have done everything in my power to make her happy, but she always displayed fear, aggression, repetitive or focused behaviors, and antisocial tendencies more so than what I have observed as normal betta behavior.
There was no sign of illness other than strange behavior even up until yesterday. I have never noticed anything physically wrong with her. She was nothing short of the perfect female. When I went to feed her she floating at the bottom with her face buried in the stones (one of her odd behaviors- she would constantly digging around in her glass stones). Her body was paled and she had bright silvery patches on her fins. From what I have read, I think she died from myco.
When she first came to me I had to take her away from the other QTd girls because it was stressing her out. I set up something separate for her in my room where it was more private and added all the tank cover I could scrounge (including a live plant that I bought from LFS. The plant came from their NPT that also houses fish, snails, etc. The LFS is not known for its cleanliness or even great fish care. The plant was not in that tank for long before I bought it).
My set up seemed to help her feel slightly more at home, but she refused to associate with us and continued her repetitive behaviors. After she had been with me for a week, she still seemed great so I took the plant out and put it in the main planted tank where my sorority is to go. That was about two or three days ago, and then she dead this morning.
Although I would like to know whether she got sick from the pet store/plant or if she came to me sick, the question is really if that plant has now spread her disease to the main tank. This sounds horrible, but I placed the plant with one of the weaker females I am less attached to and I am watching her carefully to see if she displays any signs of illness.
I have to try to do whatever I can to salvage the tank or else the 8 other females will be homeless. I cant really afford to start completely over and chuck my substrate, plants and filter for new ones.
Is there any possible way to disinfect and sterilize the tank, plants included, to make sure it is safe for the others? How can I save everything. I am willing to have to start the cycling over again as long as I don't end up giving all my pets funeral services.