Hey Dude i just read you're post .. the thing about guppies is that not all fish will eat them I had to turn my Oscar loose in the tank to clear them out .. Oh and a small warning for you guppies breed like flies i had about 100 in a not so large tank about 100 L or 25 gal tank they made the ammonia and nitrate levels sky rocket you're better off trying rosy barbs we get them here in Aussie as a feeder fish but they look kool to and are a very busy fish the Sharks may eat the young but probably not the adults .. but hell you can always sell the offspring i was breeding to sell but it got out of hand... lol i hope this post helps