Sexing Serpae Tetras!

[28erl]

i have some serpae tetras, and one of them is looking more round than normal, and it isnt acting like it normally does! how would i tell if its a female, because it possibly could be about to drop eggs, or, which im scared of, could have some sort of disease! i have noticed that some of them have white tips on the end of the fin under the body, and the sad looking one doesnt, maybe it is female!

 

[Biulu]

Would love to have an answer to this question too! I think they are only a bit bigger and rounder than males, but have never been able to get a clear answer.

 

[28erl]

all i can think is that my 'male' looking one with the white tip on his fin underneath, is used to like, show off, because when he goes near one of the other ones without it, he like, flares it up!

 

[The-Wolf]

there are very little external differences between males and females,
the best way is to view them head on and the male is quite a lot thinner in comparison to the female.