Ok. But i'm trying to know more about kribensis. Forget that i said "... in my tank"55 liters is a small tank and kribs are territorial and aggressive. I would consider another species honestly.
Kribs need at least 40 gallons because they breed a lot and if you plan to keep fry you will need space to balance aggression. You should keep one pair. They are aggressive, sources online say they are not so aggressive, I do not find that to be true. They are very aggressive in my experience because they breed a lot. They need lots of hides and territorial separation. Males will fight, aggression needs to be spread out with hides and plenty of cover
I have a pair currently in a 30 gallon tank and a pair in a 40 breeder. The ones in the 40 are not pairing up. The ones in the 30 paired up quickly and immediately spawned. As soon as they did they went from peaceful to extremely aggressive. They have pushed all the other fish in the tank to the top of the water colum. They work as a team to constantly protect the fry. It is really amazing to watch. They give the fry signals and they respond to the parents signals. They truly are amazing fish to keep. Unless you have a75 gallon or bigger tank I wouldn't keep anything else that inhabits the floor of the tank with Kribs and I wouldn't keep another krib with them. It is asking for a fight. Just my opinion from having a couple of pairs for the last few months.