Betta and Blind-Cave?

Question
I have been thinking lately of moving my year and a half old Blind-Cave tetra, Yellowjacket, into the 20gal that houses my slightly older Betta fish, Fennel.

I know that, being blind and of peaceful temperament (at least, mine) I won't have many problems from my Blind-Cave, but I'm uncertain as to how a betta might react.
He (my betta) has been moping a lot recently (I assume this, as eats normally and looks perfectly healthy) so i thought that such might break his depression at least somewhat.

Regardless, should I keep my Blind-Cave in his tank with my Red-eyes, or is it possible to keep these two as permanent tank-mates?

Answer
There is a very good chance that if you add those fish to your Betta tank there will be problems. Male Betta's are used to being alone and do best that way. On the other hand, some Betta's get along with other fish. If you do try to put them all together, make sure you are there so if something goes wrong you can separate the fish.