Can goldfish remember better in cold water than hot?

Yes, goldfish descended from ancient-Chinese coldwater Carp. Although they may have drastically changed in appearance (since ancient times) that aspect of their lives has stayed the same. It can be accurately assumed that the fish probably evolved to be better suited for coldwater because of the distinct advantage; coldwater contains higher dissolved oxygen levels.

Goldfish prefer temperatures in and around 65-70F, but will tolerate temperatures up to 80 degrees, though it is not ideal.