Labyrinth organ

[Marcus Wong]

Could someone pls enlighten me when the labyrinth organ of the fry would develop? Some say 10 days. Others 3/4 weeks. Many suggested that the fry tank shd be covered or wrapped so that the cool draught would not kill the frys on their first breath of air. Is this true? How long will it take for the organ to develop completely?

Thanks.

Marcus