Researchers have discovered that one African fish species can reproduce at just 17 days of age: a record among vertebrates. The span of a generation for these fish is one single month, which is another record.
Scientists were investigating fish of the family Nothobranchius. The N. kadleci was able to reproduce after just 17 days; the N. furzeri after 18 days. In less than three weeks after hatching, then, these animals are sexually mature. This is a record for vertebrates. The fact that the eggs of these fish can hatch very quickly — under optimal conditions, in only 15 days — brings the generation time down to just one month.
These optimal conditions are not average, however, so the fish don’t always reproduce so quickly. When conditions are not as good, the eggs can take as long as a year to hatch. This is a good adaptation for the environment in which the fish live: in small pools on the savannah, where there is a wet and a dry season. The fish can survive well in the wet season, but not in the dry. The eggs hatch as soon as the wet season has begun, and they develop with breakneck speed to make reproduction possible. When the dry season starts, development stops until the next wet season.
This study was published in the journal EvoDevo.