This is an mbuna from near Likoma Island in Lake Malawi commonly called an exasperatus. Both males and females are nearly identical when young. They have silver bodies with orange speckles. But as juveniles, you can start to see the blue hue starting in the males. This is the only fish I have ever purchased at Petsmart. I purchased this single male as a full grown aduly in 1998. The color was unusually bright and so I just had to take the chance. I kept him for five years and then sold him at a club auction in 2003. So contrary to internet knowledge, not all Petsmart fish die immediately. Their aggressive behavior is a bit different from what I've observed in other mbuna. Instead of lip-locking, they tend to do this lightning fast dive-bombing bite. I understand that this is how they feed in the wild.
There is also a similar species called Labidochromis textiles. They are very rare in the hobby, yet many hobbyests incorrectly believe they have L. textiles when they actually have L. joanjohnsonae. That's simply because they are nearly indistinguisable as juveniles. The Labidochromis textiles look identical as adults while the Labidochromis joanjohnsonae turn completely blue. According to Ad Konings, the Labidochromis textiles has unicuspid teeth and the Labidochromis joanjohnsonae has bicuspid teeth and a "normal" shaped dental arc.