I would pass on the black. The reason I have a solo striped kuhli in with the pack of blacks is that he survived in a tank--he'd gotten under the UGF, and I didn't know about it until I tore the tank apart, months after he'd gone missing. I rescued him from the gravel, and put him in the 40 I setup. Felt bad, so tried to find him some friends, and found the blacks first. Bought a trio, had one jump. The striped never chummied up to the blacks, and it would be almost impossible to get him out of the tank now--they are dreadfully hard to catch.
I am proud of my little family. Wish I knew why they are so happy (there are at least 3 age classes in there now!) so I could share the information with others. Just this weekend, I did a water change and saw 4 of the little buggers, just under a half an inch. It amazing--they swim away, curl around a rock and blend in so well--you know it's there, but it's hard to see. The very small ones have taken to hanging out in the cave with my L168, who doesn't mind sharing his hidey hole with a pile of squirmy loaches.