While you can go all-out with a large and expensive saltwater aquarium, starting with a small freshwater setup is just fine. I f you’re looking for a way to lower your stress, improve your health and get your children off the couch, part of the answer may be fish — not eating them, but keeping them.

Whether you choose a small tank with a few freshwater fish or a stunning saltwater setup that makes you feel like a deep-sea diver without getting wet, you’ll be getting some of the proven health benefits of keeping fish.

“It doesn’t have to be difficult to keep fish,” said Dr. Roy Yanong, a veterinarian with a lifelong love of fish-keeping that he pursued into a career with the Tropical Aquaculture Laboratory at the University of Florida.

“Depending on the species, you can start with a 10-gallon tank. But you always have to think about the water,” he said. “Fish make ammonia, which is excreted through their gills. You need the right number of fish, and a bio-filter with the right set of bacteria. If you don’t have that, the water will turn toxic, and that’s when fish die.”

But just as you don’t need to be an ichthyologist — a fish expert — to keep healthy fish, you don’t have to be a chemist either, says Dr. Yanong. All you need to make sure the water is right for your fish is to test it yourself with easy-to-find kits, or have it tested at a specialty aquarium store.

“Help with fish-keeping is pretty easy to get,” he said. “You can talk to someone who’s keeping fish successfully. You can also find sites online that can help.”

Dr. Yanong has been working with fish since 1992, which is also when the popularity of keeping aquatic pets started to grow. While the more complicated and expensive saltwater setups have remained the interest of only a tiny percentage of dedicated hobbyists, keeping freshwater fish has risen steadily for the past two decades.

“That’s a pretty good rise,” said Dr. Yanong, who, despite having fish all around him pretty much all his working hours, still keeps a tank of mud-skippers nearby. “Aquaria is a where a lot of kids first got their interest in nature. I know I did. And while any pet can be an entry into the world of nature, the fascinating thing about fish is that you’re not just keeping pets, you’re running an ecosystem.”

At a time when it’s hard to get kids to put down the video console and get off the couch, experts say looking into a fish tank may be key to getting youngsters up and out the door — perhaps to a career in science. And it can all start with a small tank and a couple of guppies.

(Video bonus: Training expert Mikkel Becker demonstrates the proper way to teach children to safely hold a cat or small dog: vetstreet.com/ train/how-to-pick-up-and-hold-a-cat)