I will pile on - Liveaquaria customer service is spectacular. Whenever I've had an issue, they have made it right. Fish from Divers Den are almost always in perfect shape; Liveaquaria, a little less so. That said, when there is an issue, it is taken care of.
Latest example: I jumped to order a nice pair of clownfish from DD (sometimes you have to be quick to get ahead of anyone else who may be interested). Bonus, I used a 20% coupon. A couple of days later, I got a call letting me know that one of the fish had died, and they were canceling my order. I kept an eye on the site for the single fish to show up, and sure enough, it did. I liked the pattern on the fish, so I bought it. I called and asked if they would honor the 20% coupon, since this was related back to that purchase of the pair that they canceled - "sure, no problem". A couple of days later, instead of receiving the single fish I bought, I received a different PAIR of clowns in error.
A quick call to Liveaquaria, and they refund my purchase and tell me to keep or donate the clowns (they can't get them back). Yikes, I wish they had not gotten the order wrong in the fish place! It happens. They then call me the next day to let me know that they still have that single clown, and if I still want it, they would ship it. I agree to that, but check out DD in the evening and see another pair of clowns, similar to the first pair I tried to buy (but that they canceled because one fish died). I order that new pair, call to get the order canceled for the single clown (the one where they erroneously sent a pair of clowns instead), and ask for the 20% discount, again. "Sure, no problem".
I have ordered quite a few fish from DD, and have never really had significant issues. When I have had issues, they take care of it, hassle free. I don't know how much they are really making off of me, but they make me feel like their most valued customer whenever I talk to them. It is a nice feeling!