LOL, read the info in the link, and spend some time reading/searching in the illness folder. I have already explained deworming meds in your other thread, and what you need, and why. The rest can easily be found in the illness portion of MFK, lots of recent threads about deworming. Metronidazole is not a deworming agent.
As I explained in your other thread, your fish may not even have worms, but considering its extreme stunted size, it's eating habits, and that its a FH purchased in Malaysia, I would most definitely want to rule out IP's and worms. That, or you simply have a genetically dud of a fish.
The rest is up to you.