Well of course it is impossible to tell by a picture, but I am going by this wild eye female look s/he has in this picture.
This is a link to a sticky post on here, where I posted some video on behaviours to look for that can help you guess better what sex your fid may be.
There is also a link to DNANow, it takes you to the Australian site but you can change the country selection once you are there, if you want to order a free dna kit, there is a small charge for the test. Very affordable.
Cheers !