Yes, the electric blues are pretty fish, but they are cichlids. African cichlids, dwarf African cichlids included, are somewhat territorial and don't appreciate others hanging out in there turf. They will try to claim an entire 55 if they think they can. (2 pairs of dwarf African cichlids would bicker and fight constantly in a 55 even of there were no other fish.) What the person could do to help minimize aggression is create territory structures in the tank at one end for the electric blue. Electric blues come from rocky shores and use hard scaping as boundaries. The other fish don't understand the boundaries thing and will likely take a while to figure it out, but it would help. Also, rearranging the way the tank is decorated will create a need for the electric blue to reestablish territories (fight) all over again, so once she has territory structures in place she should avoid rearranging in the tank while she has the electric blue in there. If you are able to leave suggestions she may find it helpful. Depending on the type of goldfish she has they may be easy targets because they are a slower pace, go with the flow type fish. If they are like fantails or orandas, even more so.
Learning BEFORE buying can make life so much easier on the fish. I've done my share of impulse purchasing myself. Its not fair that the fish suffered because of my mistakes. With the internet and all of the support its easier to ask about fish then it was even a decade ago. If at any time anyone ever has questions about freshwater fish/aquariums, feel free to PM me. If I don't know the answer I'll help with researching.
The information that that person put up in the
Petsmart website is great information for others to learn from. I applaud her ability to share her experience of a situation that didn't work out the way she thought. Too many people would not say anything for fear of people knowing they made a mistake. Her comments will likely prevent others from making the same mistake. Good for her!
When people make mistakes, try to be understanding. Not everyone is on the same learning curve as we are. None of us know it all (and never will). The best we can do is share the things we have learned to help others. The person that bought the electric blue likely wasn't aware of the behavior of those fish. Its likely the person that sold or gave her it didn't know, so couldn't explain it. Its possible the person selling or giving that fish away was unaware of the tankmates it was going to have. There's so many possibilities. Bottom line, she took the step to do the right thing after learning herself.