Why does my molly always "relax" his dorsal fin?

[allysonwonderland]

It's not exactly clamped...he just never puts it up. For the first few days he would display it about half the time and keep it down the other half, but for the past 2+ months it never goes up. It has such a pretty shape, too. He's a lyretail dalmatian.

Here's a picture of how he always looks, compared to another molly I have. BTW does anyone know the name of the orange and black one? I feel like I've seen them called harlequin before but I'm not sure. He was sold to me as a female swordtail -_- in the wrong tank and the girl didn't know the difference.

 

[twiddlemuffin]

I'm not sure about the fin but I read somewhere, can't remember where, that it could be called a stardust Molly.

 

[Canary bird]

I have a female Molly just like your orange one , and they told me she was a Dalmatian Molly ! And on that note I've bought platys and the girl in the shop said no they are mollies ! Useless .. I don't know what type of Molly they are but their babies are beauties mine bred with my male Dalmatian ..

 

[delfisherman]

They are gold dust or panda mollys. I used to breed mollys. When you get a new male they try to establish dominance over the over males because the bigger the sail and the more they keep it up it helps secure his dominance. Once established i noticed they hardly held it up because it takes alot to keep the sail up.

 

[bettaowner]

I could be wrong but the fin is used by the males to attract mates.