in this case risk does not make life worth living, it can end it. i dont think there are absolutely no pathogens or parasites that can pass from insects, worms, etc. to fish, and even if there are none, there are other risks such as chemicals (if you collect them from outside which shouldnt be done in the first place). in the end i know pellets and other prepared foods are safe and i i know there are enough of them to provide a varied diet. thtas what i would do and recommend, it is the safest thing to do, and when you are responsible for the animal's life, you should do everything you know of that is good for it, and nothing that you know may not be.
there are many different outcomes an overstocked tank can have. i do not think the liekly one is a bunch of fish in a clean and enjoyable tank that dont mind sharing space with eachother. diffusing the aggression i know can work in some cases, but i think of it like this: if each fish puts out x amount of aggression, and there are 20 other fish in the tank, then they can only put 1/20 of x out to each fish, but each fish is getting 1/20 x from each fish, still adding up to 1 x. (tell me what you guys think of that theory) the most likely outcome from my experience is the biggest/most aggressive fish takes charge and all the others suffer for it. and you still have an overstocked, dirty, hard to keep up with the maintenance tank. the most successful tanks are low stocked, where everyone gets their share of food, is low-stressed (as long as you remove bullies or the ones who get picked on), and they end up with the best colors and size.
there are many different outcomes an overstocked tank can have. i do not think the liekly one is a bunch of fish in a clean and enjoyable tank that dont mind sharing space with eachother. diffusing the aggression i know can work in some cases, but i think of it like this: if each fish puts out x amount of aggression, and there are 20 other fish in the tank, then they can only put 1/20 of x out to each fish, but each fish is getting 1/20 x from each fish, still adding up to 1 x. (tell me what you guys think of that theory) the most likely outcome from my experience is the biggest/most aggressive fish takes charge and all the others suffer for it. and you still have an overstocked, dirty, hard to keep up with the maintenance tank. the most successful tanks are low stocked, where everyone gets their share of food, is low-stressed (as long as you remove bullies or the ones who get picked on), and they end up with the best colors and size.