Yes, fish is delicious and generally good for you. Many national public health and diet campaigns even recommend eating more fish, contradicting all the appeals from organizations and institutions concerned about the state of the seas.
There are many similarities with the case of meat. There was once a time when diet campaigns recommended eating more meat and milk. Today, the animals that end up on our plates are often raised intensively, pumped full of hormones and antibiotics and fattened rapidly to increase profit margins. We only eat the choice pieces, discarding less-prized cuts and offal. Smaller or skinnier breeds are less profitable and so disappear. Organic waste contaminates the water table.