I put my pair of Kribensis into a 95 liter tank and found them very aggressive towards each other. I later found out that when they breed, they get very aggressive and, if they don't have other fish to chase off, they will start biting and chasing each other. So I bought some fast swimmers for them to chase and it worked. Make sure the target fishes are faster than the Kribensis, so they don't get hurt badly. Some good fish to get are tetras or barbs.
I find kribs to be very flexible fish. If aquired at a younger age from a breeder and placed in a large enough community tank (200 liters and up) they will grow up to be wonderfully friendly and energetic communtiy fish. If they are acquired at an older age when they have already turned into the fish they are going to be (personality wise) and are placed in too small of a tank, then they will most likely be a little less flexible and more aggressive, this is even more so if they are wild caught. When you buy these fish in a pet store, they have almost no color. The four I've owned over the years (three at once, that lived for three years, and a new one I currently own) have always looked gross, that is, till I put them in a good tank. Pictures don't do a healthy male krib justice. They are beautiful, my last male would replace all of the gray on his body with that deep red and the neon highlights on his fin would look so sweet, glimmering as he would swim. A funny thing is that mine have always changed color almost instantaneously to show how they felt. For example, when I would stick my hand in their tank to rearrange something, they would turn totally gray, lose the stripes and everything, in a matter of 3-10 seconds. When they want to impress/scare, that is when they look the best, kind of like a male betta. These guys can fin nip, but I've found this to be different for every fish. I recommend getting them for a semi-aggressive tank setup if you only have one tank, because getting one for a community tank and finding out he wants to de-fin your angelfish isn't good, especially when you have nowhere else to put him. He will most likely adapt without difficulty. Again, these fish have different personalities, such is their charm, so don't expect a formulaic pet.
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