Texas Cichlid Sexing

Question
I have numerous sites. All state roughly the same thing, with a few oddballs. The female Texas Cichlid will have a "largish black spot on the spiny portion of their dorsal fins that males lack".

I work in a petstore so I have access to numerous Texans and are currently looking for a breeding pair for myself. I took home 5 of them temporarily to watch and see if any will pair off. I would then take other 3 back to store.

I have looked at countless Texans and I can not identify the "largish black spot on the spiny portion of their dorsal fins that males lack". I even looked online at hundreds of photos some clearly stating sex of the Texan and I still do not see this damnable dot lol

Can you tell me in detail where to look for this dot, a couple of photos with the dot clearly circled would be of great help.

I feel like a moron asking this since it seems everyone on the "web" can identify them but me haha

Any other noticeable different sex traits would be appreciated as well as how large the fish would be on average before that damn dot appears or other sexual traits of the Texan.

Answer
I really don't have a clue but I did find this bit of information on a site(http://fish.mongabay.com/species/Cichlasoma_cyanoguttatum.html), Males, with age, develop a large bump on their forehead and are brighter colored. Males have a pointed genital papilla.
Is this what you are looking for? Are you sure it is a Texas chiclid? Have a great day and email me again if this helped!