Question about sexing A. lyonsi

[fug202]

It's my understanding that female A. lyonsi typically have a dark patch on their dorsal fin. But is this patch obvious in smaller individuals (2-3"), or is it something that only becomes obvious when the fish is sexually mature or breeding? I have four individuals in this size range, and none have a prominent patch. The smaller individuals have a faint extension of the vertical stripe, but it is not obvious and not nearly as bold as what I've seen in photos of breeding individuals. Just wondering if I should be searching for a similarly sized female, or whether the patch might develop as the fish mature.

Ian

 

[TMSB805]

I've kept a few lyonsi in the past and i'm currently keeping a m/f at the moment. From what i've noticed in the females i've had in the past the black blotch was hardly visible or almost none existent. These fish were a little more than 6". Now with the female i currently have which is about 4.5", her blotch is clear as day but it didn't really show until i moved her into a tank with a larger male.

i had the same issue with my nourisatti. I thought for the longest that i had 4 males because none of them showed any black blotches in the dorsal. About a week ago one started to display the black in the dorsal. They're all about 5-6". I think the blotch becomes more prominent in some fish when they start to show some interest in spawning. Just my thoughts

 

[duanes]

I agree about the prominence of the patch sometimes being obscure when a male is not present.
I don't have pics of lyonsi but just for reference.
female nanoluteus

male

a more obscure marking on a young female carpintus

a male

 

[fug202]

Thanks guys. Based on your information I think I'll play the odds that at least one of my four lyonsi is female.