Siamese fighter male or female ?

What is your tank size?

IMHO, male and female bettas should not be kept together w/out dividers in anything smaller than a 55g, and even then, precautions should be taken.

In the past it was easy to tell as the females were generally a dull brown colour. But now they come very colourful. And there are varieties of short finned males out there. Unfortunatly the temperment of females and males can be very unique to each fish. They both have the ability to "snap" and go on a tear around the tank. Some are more shy than others. This can also mean that they will live together fine for a few weeks, a few months , even a year but couldattack each other at any time, particularly at mating time. So keep a close watch on them.

As to what you have, it is more likely witht he commonly available species of bettas out there that you have a female (short fins) but never take that for granted. Look for signs of swelling when the male is building bubble nests, this could mean egg production.

The only reason to keep male and female bettas together is to breed them. If you have a set-up that is ready for that, great.

Keep as many females together as you want.

Putting a male in with a female - or multiple females - is asking for trouble IN MY OPINION OF COURSE. They're called Siamese Fighting Fish for a reason, and while they may not fight like two males would, the result will be that someones going to get damaged once the fight begins...and it WILL begin. If you simply must, then provide LOTS of hiding places.

Also, I've never had any difficulty telling the males from the females, it seems like pretty basic fish knowledge to me; fish knowledge 101. Don't want to take anything away from any previous posts, of course. Sorry if I offended anyone.

A common problem is mis-labelling. Many LFS think that all short fined fish are females, which is often not the case. There are a number of short finned males showing up in more places, and this increases the confusion. Short finned fish are not always male, and it's important to identify the gender before mixing them. The females are generally smaller but bulkier than the males. Short finned and half-moon males will flare at the sight of a known male, while females will not.

With all due respect to one of the above posts, there are many varieties of betta. And some of those varieites include short finned males. Betta Sp. is but one variety, though the most common sold. Also the closer a betta is to its wild roots the better the chance of producing a short finned off spring.

Female bettas have an eggspot between their ventral fins, thats the most reliable way to tell the sexes apart. Its a small white dot on thier belly where the ovipositor is.

I have a female betta who flares at all other bettas male or female and who usually has a bubble nest going. She has very long fins for a female, although still much shorter than a male. Sometimes I get to doubting myself and check again for that eggspot just to make sure.

Oh and onlynew if you still have all those bettas in the same tank...you are asking for trouble. Get the male out for sure. The females can probably live together if there is room enough and places for each to retreat, just watch them closely for awhile to make sure they dont harm each other while they sort out the pecking order. And I myself would either have only one female betta in a tank, or at least 4 of them to reduce harm done to the lowly fishies on the chain.