Yeah, the TTM sticky is a good place to start and you can decide if you want to go that route.
Along with what Grimreaperz said, I'd add to look for white or stringy poop. That can indicate internal parasites and you'd want to treat that with PraziPro. Many people also treat everything with praizi as a precaution.
Also, if your QT is not cycled, or if you have doubts about whether it is fully cycled, make sure to do frequent water changes and also add Prime to your tank to neutralize any ammonia. Ammonia is toxic in even very small doses (and will their burn gills well before you see them acting funny from it), so make sure to keep your ammonia at 0 the entire time.