Pictured in this week’s AquaNerd Picture of the Week is a Klein’s Butterfly (Chaetodon kleinii) enjoying some open swimming room in a large reef aquarium. These butterflyfish are quite popular with marine aquarists, as they have a penchant for pest anemone destruction, Aiptasia in particular. These fish graze on the pest anemones with an almost voracious appetite, and many are purchased for that reason alone. It has been said that a single Klein’s butterfly can decimate a big population of Aiptasia in a single evening, which is a story we’ve heard a few times in fact. If peppermint shrimp don’t live up to their reputation and you don’t have time to zap or kalk paste every single pest anemone in your tank, then a Klein’s butterfly might be your answer.