Oddballs or Unusual

Oddball and unusual freshwater fish are the conversation starters of the US aquarium hobby. This category is home to the weird, the wonderful, and the rarely seen — from freshwater puffers and ropefish to bichirs, arowanas, knife fish, and lungfish. These species often have unique behaviors, unusual body shapes, and fascinating personalities that set them apart from typical community fish. Many oddballs are predatory or semi-aggressive, requiring specialist care and dedicated setups, making them popular among experienced American fishkeepers looking for something different. Whether you're searching for a dinosaur bichir, a figure eight puffer, or a black ghost knife fish, browse auctions and fixed price listings from US sellers who specialize in the rare and unusual side of the freshwater hobby.