Small contest

Researchers have found one of the smallest known fish on record in the peat swamps of the Indonesian island of Sumatra. Belonging to the Paedocypris genus, the fish (see inset) is just 7.9 millimetres (mm) long at full maturity. To keep their size down, the fish abandoned many of the attributes of adulthood -- their brain lacks bony protection and the females have room to carry just a few eggs; the males have a little clasp underneath that might help them fertilise eggs individually. Being so small, the fish can live even through extreme drought, by seeking refuge in puddles. But they are now threatened by humans, widespread forest destruction, drainage of the peat swamps for palm oil plantations and persistent fires, which are destroying their habitat.

But Ted Pietsch of the University of Washington, USA, has claimed that the fish is much larger than a species of deep sea angler fish (Photocorynus spiniceps). He claims to have found sexually mature males just 6.2-6.5 mm long (encircled) attached to the female.