Mine came from the same batch, smallest big cat I have ever seen. Mine started out life in a 3ft tank with a baby juerense and 1" koi ( six) as clean up crew. For the first 2 month he left everything alone and are just bits of mussel, prawn or blood worm but in moderation. Then he started to attack the koi tails and decided he didn't like the juerense. He was moved to a 4 foot tank at maybe 2.5" and has lived there since with 3" koi( 15) growing on. Again he went for tails but was just as happy to eat mussel, white fish or pellet. The number of koi kept the aggression down but recently all the koi moved out and were replaced with a new batch of just 3 off 3" fish. He is now 3" and it took him all of a week to reduce his tank mates to one. He is about to get a 4" liarius marmoratus as house guest so we will see how that goes in a 4ft tank. So far, yes, very reminiscent of the wykii and will be very difficult to put the two together in the same pond, the jau will have to be at least 2ft long before I even try. Will look to update my thread with pics too.
