The tiny annual fish of Africa live in temporary puddles created by seasonal rainfall, and so must grow and reproduce quickly in order to lay their hardy eggs before the waters dry up.
Scientists have been able to study the short life of the African annual fish for the first time. It is believed that the fish have the most rapid sexual maturation of any vertebrate species. Startlingly, the African annual fish can grow up to 23% of their body length in a day. The fish are mainly found in East Africa from Sudan to northern South Africa. It is estimated that there are around sixty different species.
The reason behind the short life-span of the fish is due to the nature of their environment. The tiny annual fish of Africa live in temporary puddles created by seasonal rainfall, and so must grow and reproduce quickly in order to lay their hardy eggs before the waters dry up.
Scientists have now estimated that one species, Nothobranchius kadleci, starts reproducing at 17 days old and at a size of just 31 millimeters in length. The fish produce eggs that develop to the hatching stage in around 15 days. This makes the time from one generation to the next as little as one month.
In contrast to the tiny fish, the tiny cave-dwelling salamander, olm (Proteus anguinus), lives for over 100 years, takes 16 years to reach sexual maturity. In contrast to most amphibians, the olm is entirely aquatic, and it eats, sleeps, and breeds underwater.
The research into the African annual fish has been published in the journal EvoDevo in a paper titled “Rapid growth, early maturation and short generation time in African annual fishes.”