PLEASE ANSWER FISH JUMPING OUT?

ok so i just got 2 new fish their called african barbels or barbs or a hippo fish they look like a full grown bala shark just different colors. their both fully grown 9 1/2 inches i have them in a 65 gallon tank with an 8 inch oscar 2 ballla sharks 2 plecos an iredescent shark and a culombian shark the tank has a lid and the fish store were i got them had a bigger tank but there was no lid on it please tell me why thier jumping out (too many fish right ?)and what i can do to stop them dont bullshit me on i have too many fish i dont have time one fish jumped out and i dont hear anymore bangs but please tell me why their jumping out and what i can do to stop it i put some heavy stuff on the lid but im still nervous