I have worked nearly exclusively as a production manager and ASM in opera for the last few years, after working exclusively in "straight" (dramatic) theatre before that. I am a musician, and an ability to read music is absolutely essential in opera stage management. I have heard horror-stories of folks working in opera (including directors!) who don't read music, and it just baffles me. Everyone on the production team in opera reads music - including the lighting designer. Not only must you be able to know F-A-C-E, E-G-B-D-F - you must read music fluently and be able to scan a score as you would a script. In my town, we are constantly looking for additional ASMs to work at the opera, and if they can't read music or if they hesitate and say they read "a little", I simply cannot hire them. If you cannot read music, you cannot stage manage opera. It is common in the opera industry to hire ASMs from across the country, simply because the applicant pool is so shallow. I encourage you to learn to play an instrument and become fluent in reading music. Don't waste your time learning the languages - Italian, French, and German mostly. If you have a knack for sounds and if you spend plenty of homework time before rehearsals learning the arias, you'll be able to jump right in the rehearsals when the director wants to pick up after "Meta di voi." The balance of power between the maestro and the director is a new flavor that you won't find in other disciplines. As Matt mentions, there are many different concerns in opera when there is an orchestra involved - eventually, you should learn the AFofM, AGMA, and IATSE union rules so that you can run rehearsals most effeciently. There are a ton of tricks I've learned from opera stage management that are also helpful in other fields: 30-second timings throughout the score, script tabs with aria/scene first words, and many other stage managment rituals that make the whole production smoother for everyone. Opera is a truly unique field and, I have come to believe, a discipline of stage management where if you can do this, you can do anything. Please PM me if you have any specific questions - I love stage managing opera and am excited to share any experiences that might be helpful to you.