Reply #13: Yes, and I wouldn't worry about farm-raised tilapia

[EstimatedProphet]

Tilapia naturally grow in close proximity. There are fish that don't raise well in large numbers (catfish as an example) but what typically happens is overcrowding effects the water quality. In cases like that there's a chance of die-offs, but things like tumors? Never heard of that.
On edit: overcrowding can lead to disease, but nothing that could be transferred to humans, anc certainly nothing that cooking wouldn't completely fix.