I looked it up on the internet and it said you can use table salt and vinegar to clean pennies I was wondering if it would still work if I substitute iodized sea salt and apple cider vinegar?

I have read that it releases toxins that will kill other fish, do you recommend we get rid of ours now?
We just purchased it and are extremely concerned about our other fish. What are chances of it diying?

My sea apple is stuck on the glass but limp and opened up. Its tree like opening is hang downward.

I recently got an (Australian?) Sea apple from the pet store. They told me it filter feeds, but knowing their reputation and experience i’ve had with them, im not sure if i can trust them 100%. I did give it some crushed flakes, and Coralife invertibrate food I had, and looked like it was eating, but what should I be feeding them and how often? Also, if you know, what do starfish eat?, (I got a feather star the same day.)

9 gal bowfront, tahitian Black sand, 15+ lbs of cured live rock, 24W power compact 50/50, modified skilter 250.
ammonia, nitrites, and nitrates are all high.
wanting to put only a sea apple and zoe’s
any advice?
All R/O water used also

After the Sea Apple poison, did 100% water change, removed rock, vacuum sand. Added 1 damsel and 3 days later, he’s floating at top gasping for air. Tried to revive in quarantine tank but did not work. He’s dead. I’m at my wits end. Just started using Kordon’s Amquel+. Will do weekly water changes with Kordon, wait 4 weeks and try again. Any suggestions? Nitrates at 20-40 ppm.

will they attack each other?