Former sushi chef here.

In regards to tuna, I would not recommend buying them wholesale because the sheer size of tuna makes it more suitable for restaurant and storing it is a bitch as tuna goes bad fast. And I don't like freezing tuna because it turns into an ugly pink when you do so.

Salmon is a good choice and you should be able to get it anywhere. Ask your fish monger to give you a whole salmon specifically for you, if he knows you are going to use it for sushi, he will keep it in ice. What you do then is to break it down into filets and then you have to do a soft cure in salt water or hard cure with salt and then wash it in a water solution or water and vinegar. After that, you either have to super-freeze it for 12 hours or use a normal freezer for 3 days to kill anisakis. If your fish monger is nice enough because you did a huge order, they may let you use their super freezer, but just keep a section of your freezer for a whole salmon.

Honestly, I think your best bet is to buy kanpachi instead. The fish is not as big as tuna or salmon and they are much easier to store. Ask your fish monger if they sell kanpachi instead.

Plus, if the market is clean enough and you go early enough, try looking at their sea breams as well. I have turned many of them into ceviche and sashimi several times.

I was doing sushi in the US so the pay was really good. The problem was that I was spending all of my young years working 12-18 hour shifts 6 days a week. I would go to work when it was still dark and come home when it was still dark only to realize that the moment I got home and fell asleep right away, I would wake up sleep deprived. Also all of my co-workers are broken souls suffering from alcoholism, drug abuse, marriages gone wrong, children they are avoiding like the plague or wish they could see more often.

Also you have no weekends and I only got a Friday, Saturday, or Sunday night off once in a blue moon. Basically, this meant that the only friends I had outside of work were from the restaurant or they worked in the medical field, or they were unemployed losers and who wants to be friends with people like that? Also whenever Holidays or birthdays came up, my family and friends stopped inviting me because they knew I would say no. Now that I am a student and an intern working 9 to 5, I cannot tell you how grateful I am to be able to be around my friends again.

I loved sushi, I really do miss working in the restaurant because it was a really high paying job since I was paid in cash, but a really bad trip with angel dust and nearly overdosing in front of my mom, I figured I should probably go back to school and have an outlet just in case. A job as a sushi chef will always be there for me, but a relaxing 9 to 5 won't which is why I am getting my degree now.