Hoarding, it may seem like a complicated question but think it through.... which one of these things doesn't belong... also compare the definition of hoarding to compulsive shopping and you should see similarities.
Plus compulsive shopping patients have tendencies to turn to hoarding.
I think it would be that fish farming does not happen in the ocean environment therefore an excess of fish waste would not affect will fishes that humans consume. Another term for this is pisciculture. It involves growing fishes in tanks.