Oceans cover a staggering 70 percent of the world's surface and most life on Earth lives there.
There are more than 33,000 species of fish living in the oceans, but their complex emotional lives are often overlooked and misunderstood.
This new video by Plant Based News, voiced by PBN Co-founder Robbie Lockie, looks at some of the issues facing these fish - and what can be done about them.
The story of fish
"There are more fishes than birds, amphibians, reptiles, and mammals," says the video. "We are the village, they are the kingdom.
"And yet we share so much; the same body systems, muscles, nerves, and senses, and the same fibers than transmit pain. We even fall for the same optical illusions.
"[The ocean has] an abundance and majesty of a world more colorful and diverse than we could ever imagine."
But these depths are awash with humanmade problems; plastic has reached the deepest trenches, and the great coral reefs are dying.
Ocean dead zones, where nothing can live, are caused by pollution from farms. Magnificant species exist on the brink of extinction.
"The world's fishing fleet has doubled in the past 65 years, but they are finding it much harder to catch fish," says the video. "A fifth of all plastic pollution in the oceans is discarded fishing nets, and as one population of fish crashes, we move onto the next."
Fish farms are not the answer; with billions of fish confined in close proximity, they are riddled with disease and, as the video states, 'live in abject misery'.
"More than a quarter of wild-caught fishes are used to make farmed fish feed. It takes 120 wild-caught fish to raise a single farmed salmon to reach your plate.
"There are solutions; together we will create incredible marine conservation areas with strong regulation, together we'll refuse to eat farmed fish that causes cruelty and decimates wild fishes, together we'll inspire fisheries and fishermen into more sustainable food production. Together, we'll rethink how we treat the most exploited beings on our planet."
This video, which is available in English, French, German, and Spanish, was created by Plant Based News in collaboration with Compassion in World Farming, as part of its Rethink Fish campaign. You can find out more here