Well how big is yours about? if it is in the 6-9 inch range it will be easier. look at the anal fin and if it is bulky it is a male if it is thin it is a female. but if you have a smaller bichir like 5,6 ,7 some times even 8. some males bloom later so you are really looking for the males out of the bunch and if the anal fin stays thin to about 9 inches it would be a safe guess that it's a girl.