HELP, ALL FISH ARE DYING!!!

Jakewareham · Oct 28, 2018

So I'm new to the saltwater hobby, my tank is a 45 gal reef tank about a month and a half old. I'm currently hosting a clown, Vanderbilt chromis, and some inverts such as a pistol shrimp and a couple emerald crabs. Anyway I'm running into extreme trouble, I didnt realize the significance of a QT so I didnt qt any of my fish(I do have one setup now, tho I think I'm already in trouble) it all started when I added 2 Vanderbilt chromis... one bullied the other one till the point the got sick, he eventually died, the next couple of days we noticed white spots on the bully and wondered if it maybe ich, it cleared up but within a couple days later the chromis broke out with some kind of leison, ever since we added the chromis we've lost an engineer goby we have no idea what happend to it, and we just lost a watchman goby that seemed as hearty and healthy as could be with no spots sores or nothing? The clown seems happy enough, the Vanderbilt with the sore is scraping his spot on the rocks sometimes, hes still eating though. Treating the tank with melafix and an antifungal agent right now but I'm worried it maybe parasitic and with no experience I have no idea what to do but from what I've been reading it looks like I could have to tear the tank down? really need help