I bought tuna at Lotte Mart, am I a sucker?

I don't even know if this is oilfish or tuna,
but I bought it for 27,900 KRW and ate it.
Did I get ripped off?
I heard they are being caught in huge quantities in the East Sea lately,
but this is Spanish Bluefin Tuna.
To be honest, I'm not even sure about the taste,
and I think salmon or sashimi would have been better.
It had its own kind of flavor, but I have no intention of repurchasing it.