Fancy goldfish, 10 breeds.

Fancy goldfish are the egg-bodied side of the family - Fantails, Orandas, Ranchus, telescopes and the rest - bred for shape and finnage rather than speed. Unlike Comets, they genuinely can live their whole lives indoors: figure roughly 75 liters (20 gallons) for the first fish plus strong filtration, because they are still heavy waste producers. They suit keepers who want a long-lived, hand-tame display fish and can commit to weekly water changes. The trade-off is built in: the same selective breeding that makes them beautiful compromises them physically. Compressed bodies mean swim-bladder trouble, and Bubble Eyes or Celestials are near-blind and fragile. The odder the body, the calmer the tank must be - start with a Fantail or Ryukin, save the extremes for later.