Sorry for not soo good title but it's true. I recently acquired a pair of Congicus and it seems that they poop a lot. I am not new to Bichir keeping and have kept few over the years but Congicus is the first time. I noticed that upper jaw types doesn't create that much of a poop. Endlicheri and Congicus are two main ones making water dirty. Interestingly enough I am not feeding them as of yet but still it's insane. I will be doing a big water change and see how it goes. Also I noticed that pellets cause lot of poop but if you are feeding seafood the you won't see too much crap. Just wanted to share this unimportant observation. 
