Besides the obvious benefits of steady companionship and unconditional affection, studies have shown that pets can help improve their owners’ mental, social, and physiological health. For example, pets in the workplace can reduce workplace stress and pets can improve the prognosis of people who suffer from mental illness.

Recent studies have also shown that early exposure to pets may reduce the likelihood that children will develop allergies or asthma later in life. Petting your pet can even boost your immunity. Simply petting a dog can increase levels of an important protein antibody, which acts to protect the body against bacteria and viruses. Other studies have shown that owning a dog is associated with better levels of physical fitness among owners.

Everyone should be able to benefit from these pet-induced health benefits. Unfortunately, some pets require more space to thrive than some of us can provide. Obviously, owning a pet pony is out of the question for most urban, or even suburban, dwellers. But even smaller pets like Golden Retrievers or Labradors require considerable space—they need space to run, play, and exercise, especially while still puppies. So, while some pets are simply not suited to limited living spaces, others are ideal for smaller urban apartments or even college dorm rooms. Here are some of the best pets for small spaces.

Fish are perhaps the easiest pets of all. Raising a pet fish can be as simple as buying a lone Siamese fighting fish (also known as a Betta fish)—whose space and care requirements are modest—to managing a complex saltwater ecosystem populated by a wide range of marine species. The former is a small, decorative creature whose real estate footprint is tiny, making it a great small space dweller. The latter represents an expensive and challenging investment (requiring considerably more space), which is not recommended for beginners. But either choice, or any arrangement in between, can be a satisfying way to share your limited living space with other living creatures.

Many species of birds also make excellent pets. From decorative and relatively undemanding parakeets to expensive and highly intelligent parrots and cockatoos, there are numerous options for people with limited space. Most birds raised for pets belong to the taxonomic group known as Psittaciformes (the parrots). These animals are almost exclusively vegetarian, thriving on seeds, nuts and fruits. Since the wings of larger breeds are ordinarily kept clipped, there’s little need for significant space. Most birds can be kept in appropriately sized cages, although larger species may need daily time out of the cage; preferably in a space where they can experience a bit of freedom. Crested birds like cockatiels and cockatoos require daily care and attention, but smaller species are often less demanding, requiring only a clean cage, occasional replenishment of commercially available seed mix, and fresh water.

Larger birds are likely to be highly intelligent animals that will depend on you for emotional and intellectual stimulation and interaction. Some are even capable of mimicking human speech; an endearing trait that hints at the intelligence of these clever creatures. Research has shown that a number of these birds are capable of problem solving and truly communicating using human languages. Some remarkable individuals have mastered vocabularies of more than 1,000 words.

African Gray parrots are possibly the most intelligent of birds, with a brain capacity that rivals small primates’. While their needs are greater, parrot species are capable of forming rewarding and affectionate attachments with their owners. And we’re definitely talking lifetime companion: Some live up to 70 years. Cockatiels, which are the smallest of the cockatoo-family species, make excellent pets that can live for up to 20 years. Obviously, raising these friendly, intelligent birds requires a long-term commitment.

“Toy” dog breeds have been bred for their diminutive proportions, making them excellent pets for owners with smaller living spaces. Exceptionally small breeds may be called “teacup” size, although the term is not officially recognized. Some of the most popular breeds include feisty little Yorkshire Terriers (“Yorkies”), which range from three to seven pounds and live from 13 to 16 years. The long silky hair of the Yorkie’s coat is relatively hypoallergenic, which is a bonus for potential owners who may be concerned about allergies.

Other toy breeds include the elegant Shih Tzu, the feisty Chihuahua, the snub-nosed Pekinese, the stout Pug, and the toy Poodle. Although they are small, many of these breeds are tougher than they appear. Chihuahuas, for instance, are notorious for their scrappy attitudes and fierce intelligence.

Pugs are among the oldest breeds of dogs, and they are prized as much for their sweet dispositions as for their compact size. The Pomeranian, another favorite of apartment dwellers, is an active and alert breed noted for its outgoing personality. They make excellent family pets, but their greater intelligence means they require daily interaction with family members and some space to move around occasionally.

Cats are among the best pets for small living spaces. They require less attention than dogs, and don’t even need to be taken outside on a regular basis, as dogs do, to relieve themselves. Cats also spend a great deal of time sleeping, so they are well suited to spending long hours in close quarters. Although some are maddeningly aloof, others make affectionate pets that will provide years of companionship with limited fuss.

Certain reptiles, including tortoises, lizards and some species of snakes, make excellent pets for tight spaces. Most do well in 10-20 gallon tanks, although requirements will vary depending on the size and species of your animal. Some reptile species are distinctly unsuitable for apartment life. These include any breed of poisonous snake, iguanas, and baby alligators, which may be cute at six inches, but can be downright dangerous at six feet or more.

The Leopard Gecko is considered the simplest of all lizards to raise. Their needs and space requirements are minimal. Unlike many reptiles, they don’t require potentially expensive supplemental ultraviolet (UV) lighting. Bearded dragons are also recommended for novices. These calm reptiles are easy to handle, but require a larger tank than the Leopard Gecko, and need UV lighting to thrive. Keep in mind that many reptiles are long-lived, so buying a reptile represents a significant long-term commitment.

Owning a pet can be a satisfying experience that even apartment dwellers can enjoy, provided they choose a pet that requires little room to thrive.