Up to a quarter of fish in fish farms have stunted growth and float lifelessly at the surface of the tanks. These fish are known as 'drop outs.' According to research by Royal Society Open Science, these fish exhibit behaviours and brain chemistry almost identical to those of very stressed and depressed people.

Fish are capable of complex behavior and their brain system has a lot of similarities with that of mammals, including humans. Lead author of the study, Marco Vindas

The 'drop out' fish were found to have significantly higher levels of cortisol, a stress-response hormone, as well as increased activity of the serotonergic system, which is involved in sleep, hunger, respiration, mood and more. Problems with this neural system have been associated with severe mental illness, including depression.

I would not go so far as to say they are committing suicide, but physiologically speaking, they are on the edge of what they can tolerate, and since they remain in this environment, they end up dying because of their condition. Marco Vindas, Royal Society of Open Science

Farmed fish live in very stressful conditions, vastly different to what they have evolved to cope with in the wild. Fish in aquaculture farms are forced to live in crowded tanks and endure unwanted interactions with other fish, handling by humans, struggles to get food, and sudden changes in lighting, water depth and currents. Just like pigs and chickens, fish in intensive farms live a life of suffering.

This research suggests that the way fish cope with stressful environments is not dissimilar to the way we ourselves do. Other studies have discovered that the intelligence of fish far surpasses what we once thought. A specialist in fish behaviour from Macquarie University (NSW), Dr Culum Brown has said 'Fish are more intelligent than they appear. In many areas, such as memory, their cognitive powers match or exceed those of 'higher' vertebrates including non-human primates'.

Sadly, fish who live in the ocean are not free from cruelty. Every year billions of animals are pulled out of the water in huge nets to be killed for 'food'. As animals are pulled to the surface, many are crushed to death under the weight of so many other animals. Others suffer from burst eyes and organs due to the sudden change in pressure. Those who are not dead before they hit the boat deck, will suffer a slow and painful death from suffocation. Dr Brown says that the suffering of fish as they suffocate to death may even exceed that of human drowning, as it can go on for much longer. "The potential amount of cruelty we're inflicting is mind-boggling" says Dr Brown. What's more, fishing trawlers kill indiscriminately, meaning that they are also death traps for seals, sharks, dolphins and turtles.

The good news is that we have the power to make the world a better place for fish. And it all comes down to what we put on our plates. It's an exciting time for animal-friendly food, as more and more people make the choice to take animals off their plate. You only need to look at this 100% cruelty-free 'fish' burger from Soul Burger in Sydney to believe it.

Sydney-siders also have the pleasure of visiting Australia's first completely fish-free, fish and chip shop — Bliss & Chips in Newtown. Nationwide, Quorn fish-free fingers are making their way into supermarkets, alongside a range of other meat-free products in the frozen section. While the Phish Burger at Lord of the Fries (various locations around Australia — and Auckland, NZ!) is a fan favourite — in fact, there were nearly riots when it disappeared off the menu for a few months. It's now back for good, and that great news for us, and the fish!

For more tips on getting started eating cruelty-free, plus heaps of delicious recipes, order your free vegetarian starter kit today.