How can you tell how old the guppy fry are?

When can you tell the gender of guppy fry And I have one female platy and one male platy and whenever the male tries to mate the female gets away how do i get them to succesfully mate 17gl aqaurium?

• Answer:

  Guppy fry are usually sexable at around 4 weeks. Don't worry about your Platys they will manage it eventually. Your 17 gal tank is a bit small for the amount of fish you will have if they all start breeding. it will actually only contain around 15 gallons when you remember that it is not filled to the top. :- 1 inch of fish needs at least 1 gallon of water but more is better. :- Every tank needs a permanently running cycled filter. :- Every tank needs at least 50% of its water replaced every week.Follow the rules and you stand a chance of keeping fish successfully. Miss out on any of them, and I can guarantee that your fish will have constant health problems.