for me its the kissing gourami, try as I might, I went through 5 of the lil guys before i admitted defeat and gave up. I fed a varied diet, plenty of room, no bullies in the tank.... dunno why but thats the fish i couldn't keep
I've always had crap luck with jurupari. I have one now that I've had for a month or so and I keep looking in the tank expecting to find it dead...so far still alive though