Metro can be very effective as a treatment but you must diagnose it early, isolate the affected specimens in a sick tank to treat, and keep a close watch on the rest of the colony isolating any others that begin to show symptoms, e.g. bloating, refusal to eat, cowering in the upper corners of the tank, etc.
If you catch it early enough many fish can potentially be saved but this disease progresses very quickly so isolate and begin treatment according to the directions. Expect, however, to lose some individuals.
For those individuals that are cured, be patient about reintroducing them to the colony assuming you have caught it early and most of the fish in the colony remain healthy. Bloat spreads very fast and fish die within 24-48 hours.
Good luck finding and using metro.
