An unusual friendship developed more than 25 years ago between Japanese diver Hiroyuki Arakawa and a local fish, Yoriko. Yoriko is an Asian sheepshead wrasse. Found only in China, Japan, the Korean peninsula and the Ogasawara Islands, this fish inhabits rocky reef areas and can grow up to 100 cm in total length. Also known as the Kobudai in Japan, the sheepshead wrasse is a hermaphrodite, which means it can change its sex since it has both male and female organs. 
This duo is not only dynamic but also iconic in every sense of the word. They became friends when Hiroyuki was charged to oversee an underwater Shinto Shrine at the Hasama Underwater Park, near Tateyama, Japan. The shrine is only accessible with an air tank, goggles, and scuba gear.
Hiroyuki started diving when he was 18-years-old. About 30 years ago, he became the best of friends with the wrasse when he saved her life and gained her trust. Yoriko had been exhausted from trying to find food, and Hiroyuki fed her five crabs daily for 10 days. He also helped her and tended to her when she was injured.
Ever since then, a strong bond formed between them. Whenever Hiroyuki dives to the shrine, he just has to knock on a piece of metal there, and Yoriko will rush to him. He then greets the fish with a kiss — he is the only human she allows to do that. 
“I’d say we understand each other. Not that we can talk to each other, but it just happened mutually. I’m not sure if it’s the nature of the Kobudai or not, but it’s probably because there is a sense of trust between us,” said Hiroyuki in an interview with Great Big Story in 2017. 
Memory span of three-seconds?
Not at all. In an interview with Vox, Australian biologist, Culum Brown said, “Everyone thinks that fish have a three-second memory. I have no idea where that started.’’
He also said that the reason why people think of fish as stupid is because we don’t interact with them in any meaningful way. This is probably because the aquatic world is so different from the terrestrial one, and you need to see an animal in its element before you can claim to understand it. 
Can fish really recognize human faces?
A recent study by Dr. Cait Newport from the University of Oxford on the Discrimination of human faces by archerfish has, to an extent, answered that question. Brain scans show that the fusiform gyrus — a part of the human neocortex — is responsible for facial recognition within humans.
The study by Dr. Newport showed that archerfish — which stuns prey by spitting jets of water at it — can be trained to recognize human faces, despite not having neocortices, the part of the brain concerned with sight and hearing. The study employed a two-alternative, forced-choice procedure and four archerfish. In the first experiment, the fish were shown images of 44 human faces, and in the second, they were shown 18 faces. This second experiment was after the color, shapes of the heads, and brightness in the photos had been altered.
The fish were trained to spit water at a particular image to receive food prizes. They were able to distinguish the right faces with impressive accuracy — 81 percent in the first experiment and 86 percent in the second. 
This certainly challenges the opinions we have of fish. Of course, more work has to be done to be able to make more sense of this “fishy situation.”
Hiroyuki’s case, while unique, is not the only case of “Unlikely Animal Friends: Fish and Human Edition’’ out there.
In Lake Tanganyika, East Africa, a little striped fish can recognize different faces. It uses this ability to keep strangers in its sight. The fish, known as the Cichlid, identifies strangers by looking at the pattern around their eyes and not at any other body parts. This is because they live in rock crevices, thus just a small part of their body is visible at any time. 
Certainly, there is still a lot of work to be done in this field of marine research.
Nevertheless, we can be kinder to fish and their natural habits. Who knows, they might be called to testify in a court case involving you someday. I don’t think you’d want a fish spitting at you in a courtroom, essentially saying, “Yes, your honor; he peed in the ocean. He’s guilty!’’
“Fish are the sex-switching masters of the animal kingdom“, BBC.
“Japanese Diver Has Been Friends With a Massive Fish For 30 YEARS“, Next Shark. June 2017.
“Aquatic Affection: How a Scuba Diver Found a Good Friend Under The Sea“, Great Big Story.
“Are Fish Far More Intelligent Than We Realize?“, Vox. August 2014.
“Fish can recognize human faces (and we know because they keep spitting at us)“, The Washington Post. June 2016.
“Fish recognize friends and foes through their unique faces“, New Scientist. June 2017.