Maybe it is because they live out in the ocean, invisible to anyone who is not able to soak into the deep sea. Maybe because it is not always possible to be in contact with them, especially when we are kids. Or maybe it is because they are unable to show their emotions…    
Anyway, fishes are one of the most abused animals on Earth, and are used not just for food, but even for entertainment.

The human consideration of fish is terribly inappropriate: in particular, fishes are believed not to perceive pain. In reality, different researches have shown that fishes do experience grief. «There is as much evidence that fish feel pain and suffer as there is for birds and mammals», wrote Victoria Braithwaite in her book “Do fish feel pain?”. To obtain these conclusions, the biologist and her colleagues exposed fishes to irritating chemicals, discovering how these animals show the same behaviour we would have: decrease in appetite and concentration, speeded breath and rub the affected areas against the side of the tank. Fish who were exposed to the harmless saline solution did not prove this abnormal behaviour.           
Neurobiologists recognized that fishes have a nervous system which understand and respond to pain, neurotransmitters which identify the aching sensation and answer it with the emission of endorphins, a natural painkiller to relieve the grief. We can understand the evident usefulness of the pain, particularly in evolutionary terms. As Dr. Yue states «Pain is an evolutionary adaptation that helps individuals survive… [A] trait like pain perception is not likely to suddenly disappear for one particular taxonomic class».

Furthermore, a study published by Applied Animal Behaviour Science discovered that fish who are exposed to distressing heat later display signs of fear and caution – demonstrating that fish both feel pain and can remember it… In addition, fish have very sensitive mouths, which are used as humans use hands. Therefore, angling cannot continue to be considered a non-cruel sport.

As about fishing for food, an Australian study found that fishes can also suffer from anticipation of physical pain: when they are chased, captured or confined, they react as humans do to stress: increasing heart and breathing rates and an explosion of adrenalin. Methods of catching and killing them are doubtless abusive. Fish are pulled up from a considerable depth, and the sudden change in pressure on their bodies causes painful decompression that often causes their gills to collapse and their eyes to explode. As soon as fish are removed from water, they begin to suffocate. It is important to note that, as Dr. Culum Brown reminds, «unlike drowning in humans, where we die in about 4–5 minutes because we can’t extract any oxygen from water, fish can go on for much longer. It’s a prolonged slow death most of the time». So, fishes experience a stress which exceed the one of a human drowning.

Besides, commercial fishing adversely affects the environment, and it is actually ruining our oceans.
As a result of commercial fishing, more than 90% of natural marine populations (included turtles, protected fish species and even mammals. See: https://www.oipa.org/international/hunting-fishing/ ) have been wiped out in the last half century. Almost every commercial fishing boat practice bottom-trawling to catch the biggest number of fish possible, but in this way they capture even other sea animals. According to scientists, the ruination caused by this way of fishing is alike to that caused by the destruction old forests, only on a far greater scale.

Even the “aquaculture”, farmed fish undergo a more-prolonged mistreatment and suffering: as all the “farming” industry, it implies large-scale, highly mechanized production, and so fishes are deprived of the freedom, and of a healthy environment, as they are all grown in huge tanks, where they are almost unable to move, are fed only with pellets designed for unnaturally rapid weight gain. Under these conditions, fish suffer from stress, infections, parasites, oxygen depletion. In an effort to prevent the spread of disease, producers give them large amounts of antibiotics. Even so, many fish die before slaughter. For economic reasons and to reduce fish’s faeces, most farmed fish are starved for days or weeks before they are slaughtered.

Both wild and, clearly more, farmed fish live in increasingly polluted waters, and their flesh rapidly amass dangerous levels of toxins (such as polychlorinated biphenyl and mercury), which obviously are assimilate and can harm those who eat them. The Environmental Protection Agency (EPA) estimates that fish can accumulate thousands of times the level of cancer-causing PCBs, dioxins and insecticides as DDT, found in the water in which they live: this is because EPA’s guidelines suggest not to eat farmed fish more than once a month.

As all other animals, the survival instinct remains in these animals, and so fishes want to survive. Their right to survive, to live a worth life, and to be considered as someone (and not something) must be spread through raising awareness: OIPA stands against all the mistreatments to which fish, intelligent and sensitive animals, are subjected, promoting a vegan diet (https://www.oipa.org/international/veg/) as the only possibility to save billions of life: not just of fishes, but also of human beings.