Shrimp aquaculture produces over 5 million tonnes annually, with welfare conditions that receive far less scrutiny than land animal farming.
Eyestalk ablation, which removes neurological tissue in order to induce ovulation, is almost certainly painful and performed without anaesthesia on billions of female shrimp annually. Poor water quality in intensive ponds causes physiological stress measured through cortisol equivalents. If shrimp are sentient, the scale of suffering in this sector is comparable to some of the largest animal welfare issues in existence.