Nasty Kribbies.

I'd return one. They will likely keep bickering, though it might settle. Are there any other fish in the tank? It might help if they have plenty of other fish to "defend" their territories from, which would lessen the aggression against one particular fish.

You could try rearranging the tank or adding more plants/decor to break up the line of sight. If they can't see each other, then they will be less likely to constantly be fighting.

I'm having a similar problem. I got 6 kribs a while back hoping for a mated pair. Turns out I've got 2 pairs and a lonely female. Not sure what happened to the 6th one...No bodies have turned up, but it might just be hiding. But now I've fallen in love with both the pairs. I'm gonna have to pick just one pair though since I don't have the room to set up another tank, and I can't move one pair to another tank (incompatability issues). At least I can move the lonely female to my mom's tank. It's sad, but it needs to be done especially since I rearranged the tank. I'm finding torn tail fins now.

Yeah, mine seem to almost completely ignore the tetras and other fish I've got. They do take a second to chase them away if they get too close to the cave, but mostly all their attention is for each other. I was really hoping that because they chose caves on opposite sides of the tank that they would be more peaceful with each other, but nope. It seemed better just last week before I trimmed plants and rearranged all the decor, but now I guess they can see each other better.

Ironically, they choose to "fight" over top of one of my pleco's caves. It's amusing to see them threaten each other there as they pretty much just stare each other down and occasionally dart a little closer and then back off. But then one will get just a little too close and get chased pretty aggressively. Then it's not so funny.

If I can catch her, lol. I offered her to my mom for her tank, so I can't really give her to you. Sorry! I tried moving her to Mom's tank (I'm setting it up for her at my place), but she was so sneaky that I couldn't get within a foot of her! Dang my decor!

Although, I did some counting, and either I lost my 6th one or I have another that is good at hiding. I should have 6 kribs, but I can only see the 2 pairs and an extra female. Don't know what happened there. But then I'm also missing 2 baby bristlenoses.

Hmm, might have to do that. Didn't think that they were small enough to get in there, but then again, they are pretty small and notorious for getting into small places, I guess.

Talked to the lfs yesterday about selling my second pair. I decided that they were just too territorial to have 2 pairs in a 75g. So, I might yet find out what happened to my 6th krib. I also got some new nets as my dog chewed up my good ones a few months back, so I only had this huge one that was about 8" by 5." The new ones have red netting, and they are supposedly hard for fish to see or something. Might help tricking her into the nets. I dunno.