Goldy (ぎょぴちゃん,Gyopi-chan?) or Lil' Goldy is Kagami's pet goldfish that she won while goldfish scooping during a summer festival.
Kagami originally won Goldy during a summer festival during episode 5 of the anime. Goldy was the only goldfish within Kagami's reach during the game, and was caught (presumably) on Kagami's first and only try. Goldy is then brought up in episode 15 during the cherry blossom festival the next year; apparently Goldy has done quite well and has grown significantly, and to an extreme, since being caught. Goldy has grown so well, in fact, that Konata remarks that at it's size, Goldy can't be a goldfish. When last seen, Kagami has pleged to put Goldy on a diet, citing Konata having made a comment about an anime, as being the cause.
"I took a little too good care of it...I can only pray that it's because he's living a good life."~Kagami Hiiragi (On Goldy's size large increase in size.)
"It'd be a problem... if he showed up as a wife beater."~Kagami Hiiragi (using a reference to the anime Angel Tales on Goldy.)
"If this thing comes back to me as an aggressive boyfriend I am so going to be hating my life."~Kagami Hiiragi (another reference to Angel Tales, this one is from the English version of the anime.)