So I always understood that you feed your fishes before adding in a new tank mate, in order to prevent harassment on the newcomer. From what I can tell, fish are dumb and WILL eat whatever you throw into the tank, it being the same kind or larger. I have roughly about 5 or 6 different kinds of mahseers in this tank which I got most from Wes, and there all roughly 5 or 6 inches. There always hungry and always wanting me to put in more food even though they been fed. I have this grow out tank which I just removed a silver iridescent shark into the tank, roughly 4 inches. I assumed that because it is definitely too big to eat and there mouths not having any teeth could do any harm, I just plopped him in there. FYI all tanks I have are regulated to be same temp throughout and I try to keep proper ph and tank status throughout my tanks. I go away and do some unfishished chores, and literally less than 10 minutes, I come back to see a iridescent shark swimming around aimlessly the tank with no eyeballs. Literally what the fudge, I putted the poor iridescent out of its misery, and for now on, teeth or no teeth, feed before introducing. Sad face.