Hello and welcome to fishlore
Cloudy water can also be a result of a new aquarium in the process of cycling. Having too much food in the tank shouldnt necessarily kill off fish unless they over ate which could happen.Its hard to say if that is what actually killed your fish.
I am noticing by your aquarium info that your 60L which is 15g us, that you have 22 fish in there? If that is correct I would have to say that your are extremely overstocked and that could be the problem. I would think about returning some of those fish including the sharks which will grow much too big for your tank. Also I would be doing at least a 50% water change daily as Im wondering if you have a lot of
ammonia in your tank. Can you let us know what your water test results are for ammonia,
nitrite and
nitrate are?