The best fish for a pond include koi, goldfish (such as comet and shubunkin varieties), and golden orfe, as these species are hardy, attractive, and well-suited to outdoor pond life. Koi require a larger pond with adequate depth and good care, while goldfish adapt well to smaller ponds. Golden orfe are active schooling fish adding dynamic surface movement. Other hardy species like tench and common carp are suitable for unfiltered or less managed ponds.