Goldfish

Goldfish were a species of fish native to Earth; they were renowned for their short memory. The First Doctor stated he wasn't a goldfish when it was suggested he had forgotten the events of a mere moment ago. (DW: The Romans)

In Cardiff as part of Torchwood Three, Suzie Costello bought goldfish in bulk and began killing them to test the Resurrection gauntlet. (WEB: torchwood.org.uk)

The prison ship containing a Minotaur had a goldfish bowl. The Eleventh Doctor tried to save the goldfish from the Minotaur when it was attacking, but Gibbis simply ate the goldfish later. (DW: The God Complex)