Berlis Aknista was an Isitri male that was born on Isitra Colony First.
In 2270, Berlis travelled to Isitra Zero in order to meet with the Isitri Council where he was discovered to be a "troublesome mind" and the Council tried to have him killed on his way back to the colony. However, the USS Enterprise intervened and rescued him because they didn't realize the danger he posed. Then, the Enterprise returned Berlis to the colony, despite Isitri attempts to stop him. Despite the Isitri's attempts to hide Berlis' existence, the Odib found out about him and sent a fleet to attack Isitra; a fleet which the colony detected first. This discovery caused Berlis to leave the colony and go to Isitra where he managed to take control of all the Isitri on the planet. Fortunately, the Enterprise was able to stop Berlis and save Isitra from destruction at the hands of the Odib by bringing Meshu, a second "troublesome mind", to Isitra and locking him in his mind with the help of Spock. Unfortunately, Spock was unable to resist Berlis' pull and locked himself in with Berlis, but he later managed to pull himself out the meld. Then, as Spock rested in his quarters, Berlis again attempted to link with Spock and Spock killed him to stop it from happening. (TOS novel: Troublesome Minds)