I would say about 3", I have a 6 inch Male that took a long time to color up, only about three weeks now that he has his full coloration all the time. Look for the spotting on the flanks and blue/green on the cheeks that they will have sometimes during agression, after water changes and feedings. Its to small to sex but if I had to venture a guess I would say Male because of the green on cheeks and little bit of spotting starting. Some females will get a little spotting so that is not full proof and then lose it.