Overfeeding any fish in a bowl with no filter will obviously kill them.
However, Piranha are vicious creatures that should be erased from the earth before they evolve into winged creatures and skeletonize us all.
Furthermore, Uric acid, in urine, particularily that of your own, is medically proven to neutralize and alleviate a number of protein based irritants, jellyfish included.
one of my favorites is that the size of an aquarium limits the size of a fish.
This is untrue, unless you starve the fish of it's natural diet. Some basic logic:
1) less room = less exercise, i.e. abnormal growth.
2) there is nowhere in the wild where a fish will encounter less food competition than in captivity.
okay, so it is improbable that any human can provide the EXACT same diet in an aquarium that a fish gets in the wild, so often they don't grow as quickly.
If you consider the life expectancy of a goldfish is, say, 75-100 years, then sure, it won't grow too much in the 4 years most people keep them in bowls.
or whatever
8O :? :?: :!: