270kg? Wow that's some moonfish. Is it related to the sunfish?

"Is it related to the sunfish? "
No.
Plus Sunfish are supposed to yield very little meat that's edible.
"For how many? "
2

#1,
That looks like a perfectly good piece of maguro tuna that's been singed on the outside in some misbeguided attempt to assuage the unwarranted qualms of Westerners, who don't believe in fresh food. If it wasn't so trendy, most people would turn their noses up at the stuff. You get no points for ruining a perfectly edible portion of fish by searing its exterior. [Rant over... but may need to be repeated for the benefit of other yahoos.]

If opah tataki meant to be whale meat, it doesn't look dark enough (bloodied) to be mammalian.

Well the meal was a success, homemade Tataki a new favourite.
Dead easy to make but as always next time I'll change some nuances.
Quite easy to sear the fish too much I see that now, and the dipping sauce could be made so many ways I just used Soy & Lemon juice.

Top ranting there, #6!
270kg for 2 people??...I know Obesity is the new buzz word but...
Anyway, you are of course correct with the rant as it really has been such an interesting thread apart from my interjection
Carry on the good work on GS that you have started in your first 3 months here...

"Carry on the good work on GS that you have started in your first 3 months here... "
GFY you disgusting misanthrope, wretched is too good a word for your psychopathy.