How can I tell if my short fin Betta Fish is a male or Female?

google image female and male! the guy above is funny.... red in water ah aha....... all males have long fins, since they need it hold on to the eggs for the female. there is no such thing as a short fin male, unless it got into a fight and lose it all. females body size is typically smaller.... http://www.animalport.com/img/Betta%20Splendens-Female.jpg while male is bigger.... http://www.bettafish.name/Betta_Fish.jpg

Male Bettas are the more colorful of the sexes, and have the long flowing fins everyone identifies with Bettas. Females have short fins, and are their colors are more drab, although some are quite colorful. The fish that you see for sale in most shops are all males. They are kept in individual containers, because males will fight with each other. Females can be kept together, however they are not commonly seen for sale in the industry.

Typically, male bettas have the brilliant colors, while the female bettas are muted/faded colors.

WIthout anoher betta, it would be difficult to tell. Try holding a mirror to it until it sees itself. If it is male it will puff up and flare and become aggressive. Go to a petstore and ask to see male and female betta fish and talk to them about the differences. A female betta has considerably short fins and are not very colorful and not nearly as aggressive.

How about trying this method. If they are not fighting, it's likely a female.

Put it in a bowl with another male. Red in the water means male. More betta fish means female.