So I bought a jurunese catfish 2 weeks ago. Very healthy when I got him and very healthy when I had him. Eating like a pig but I had to sell him because my bass didn't approve of his presence. Fast forward to today, I had an interested buyer and I agreed to sell him for half of what I was asking just to move the fish. Buyer is a cool guy whom I've dealt with before. I put the fish in a oversized cooler and plugged a sponge filter to my trucks inverter. I'm sure you guys/gals can see where this is going smh. Anyways get to the buyer open the cooler and the catfish is swimming looking great, this is at 11am, transaction is made. I get a text from the buyer at 4pm saying that during his acclimation process the fish died. I'm far from a jerk and I want to rectify this situation but not sure of what if anything I should do. I believe in karma so should I offer half back, a full refund or nothing at all?