How a little fish in a puddle gets out of a muddy muddle

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How a little fish in a puddle gets out of a muddy muddle

These killifish hatch, grow, mature and produce the next generation in world record time

Cape Town bureau chief

If you’re a fish in a muddy puddle in Africa, you can’t hang about.
When it rains, time is short before your puddle dries up, so you need to run life’s race as quickly as you can.
And it turns out that Nothobranchius furzeri, the killifish in question, are world record holders when it comes to hatching, growing, maturing and producing the next generation.
Czech scientists say the fish, which are found only in Zimbabwe and Mozambique, do it all in two weeks, “the fastest rate of sexual maturation recorded for a vertebrate”.For most of the year, they survive as dormant embryos buried in sediment. When rain forms puddles in small depressions, they hatch from a 1mm egg, grow to 5cm long and begin reproducing in two weeks, biologists reported this week in the journal Current Biology.“We guessed that some populations of this species could achieve very rapid growth and sexual maturation under particular conditions,” said Martin Reichard of the Institute of Vertebrate Biology at the Czech Academy of Sciences.“But we have found that this rapid maturation is the norm rather than a rare exception.”
His team, which surveyed killifish in eight pools in southern Mozambique between January and May 2016, also found the fishes’ lifespan was flexible, ranging between three weeks and 10 weeks in laboratory conditions.In most vertebrates, ageing occurs gradually and takes years. By studying the killifish, Reichard’s team followed several populations throughout their lives in a matter of months, and found that they displayed all the normal signs of ageing, including marked functional declines.
By comparing the timing of the pools’ filling and the estimated age of the fish, they determined that they hatched within three days of rain and were sexually mature within 14 to 15 days.
Their next objective is to explore differences within populations in different puddles and work out why males tend to die sooner than females.

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