Can a fish be depressed? This question has been floating around my head ever since I saw a sad-looking Siamese fighting fish in a hotel. His name was Bruce Lee, according to a sign beneath his little bowl.

On the bottom of the little bowl was Bruce Lee, totally still, his lower fin( 鳍 ) somewhat   injured. When   he did   finally move, just slightly,   I   got the sense that he would prefer to be dead.

The pleasant woman at the front desk convinced me that he was well taken care of. Was I simply incorrectly supposing his lethargy was a sign of mental suffering?

Later on, I sought answers from scientists. It turns out that not only can our gilled( 有 鳃 的 ) friends become depressed, but some scientists consider fish to be a promising animal model for developing anti-depressants. New research has been completely changing the way scientists think about fish, building a case that pet and owner are not nearly as different as many suppose.

Dr. Pittman likes working with fish, in part, because they are so obvious about their depression. He can reliably test the effectiveness of anti-depressants with something called the “novel tank test.” A zebra fish gets dropped in a new tank. If after five minutes it is hanging out in the lower half, it’s depressed. If it’s swimming up top — its usual behaviour when exploring a new environment — then it’s not. The seriousness of the depression, he says, can be measured by quantity of time at the top vs. the bottom, all of which seemed to confirm my guess about Bruce Lee.

“One of the things we’re finding that fish are naturally curious and seek novel things out,” said Dr. Braithwaite.

In other words, your goldfish is probably bored. To help prevent them from depression, she suggests introducing new objects to the tank( 缸 ) or changing the location of items.

Dr. Brown agrees, pointing to an experiment he conducted, which showed that if you leave a fish in an enriched, physically complex environment — meaning a lot of plants to bite at and cages to swim through — it decreases stress and increases brain growth.

The last time a guest posted Bruce Lee to Instagram he was looking good and lively. Perhaps that new green leaf in his bowl had provided the enrichment he desired.

Mary Krupa became friends with the grey squirrels during her first week at Penn State, after spotting them running around and idly wondering what they would look like with tiny hats on their heads. Today, everyone at the university knows her as the "Squirrel Girl".

Mary started bringing them food, and gradually they began to trust her. She managed to put a hat on a squirrel and take a picture. Thinking that her colleagues could do with something to lift their spirits, she started posting similar photos on Facebook. The response was greatly positive, and before long Mary and her squirrels became an Internet sensation.

Growing up in a neighborhood outside of State College, Mary was always fond of birds and animals around her home, but she didn't interact with people very much. She was later diagnosed (诊断) with Asperger's syndrome, but the squirrels changed that. "The squirrels help me break the ice, because I'll be sitting here patting a squirrel and other people will come over and well just start like feeding the squirrels together and chatting about them," she said, "I am a lot more outgoing."

And in case you're wondering how Mary is able to get the squirrels to do what she wants for her photos, it has a lot to do with food. For example, whenever she wants them to hold or play with something, she puts peanut butter on the prop (道具), and they'll grab it. But getting to that part took a while. In the beginning, she would throw peanuts up the trees on campus and invite the squirrels to come down and get them, but they hesitated to approach her. She had the patience to earn their trust, though.

This year, Mary is graduating with a degree in English and wildlife sciences. She wants to be a science writer and educate people on how to preserve the environment. As for her furry friends, Mary plans to stay in the area and visit them as often as she can.

What is the number one favourite pet in the UK? If you think the answer is “dog”—you are wrong. There are 8.6 million cats and 8.3 million dogs in Britain according to recent figures. But experts predict(预测) that there will be more dogs than cats next year as dogs become more and more popular.

Dogs as accessories(配饰)

We like to spend time with our pets. The Queen is famous for her corgis(威尔士矮脚狗) and is often photographed with them. Nowadays some dog owners are more extreme-a few TV celebrities even take their dogs shopping or to restaurants. Chihuahuas(吉娃娃犬) are especially popular as “handbag dogs” because they are so small.

Dog holidays

People are also giving their pets holidays. Many UK hotels and holiday parks now welcome dogs as guests. What about owners who go abroad? They can leave their pets at a dog hotel or dog spa while they are away. Some even provide their canine(犬) guests with a TV.

Dogs are for life

The British charity, Dogs Trust, finds homes for thousands of lost and homeless dogs every year. Their famous slogan “A dog is for life and not just for Christmas” was created in the 1970s to teach people about the responsibility of owning a dog. Dogs Trust told British people not to give dogs as gifts or treat them like toys.

Dogs on TV

Victoria Sitwell is the host of the popular TV programme called “It’s me or the dog”. In the show Victoria helps dog owners with their pets’ bad behavior. She tries to find solutions to problems such as a Dalmatian who thinks he owns the house and won’t let the family sit on the sofa, dogs that will only eat ice cream and biscuits and even a bulldog who uses the owner’s bed as a toilet. Yuck!

Fashion for dogs

You can shop online or on the high street for the latest in dog clothes and accessories. Specialist shops sell items such as dog boots, dog fancy dress costumes, dog coats, dog dresses and dog pants.