How to make my fish live a long time?

First off, NO BOWLS!

It is a huge misconception that betas and goldfish can be kept happily on bowls, but it couldn't be farther from the truth. If you want your beta to live a long and happy life, get it a tank. Make sure it has a filter, heater, thermometer, lid, and light. Betas are tropical; fish and need a water temperature in the 70's. The lid will prevent escape and provide a rest for your lights, which should be turned off at night to keep a night/day cycle. Filtration is key for oxygenating the water and keeping it clean. Feed your beta once a day with high quality flakes and supplement weekly with live or frozen brine shrimp, dried brine shrimp can cause impaction. Keep in mind, betas are carnivores. Get some gravel and live plants to provide him with plant cover for his shelter and plenty of open water to swim in. Also keep some surface exposed because betas do sometimes breathe straight from the air. And finally, do a water change once every two weeks. Betas should and have long colorful fins.

Hope this helps, good luck! :)

If you want ANY fish to live a long time, ditch the bowl.

What you need is an Aquarium.

What's the difference?

Size, heating and filtering.

With those things you can keep the conditions in there PERFECT for your fish.

Temp ~78F

Ammonia 0

Nitrite 0

Nitrate less than 30

pH 6.0 to 8.0

Now in a bowl it's just dumb luck what those parameters are, and chances are some of them wont be correct. Temperature and Ammonia most likely as you have no heater or filter.

So work on getting those parameters correct, then you can decorate the tank how you like. Lights only matter if you have live plants, which are of course an option. But you can get silk or soft plastic ones if you want. The issue with sharp plastic is just that the betta might run into them and tear a fin. This isn't fatal, but if he keeps doing it he's going to look a bit tatty. A cave or ornament is fine, there are some cool natural looking plastic or ceramic "hollow logs" that look OK

But those things don't help the fish live longer. The environment in the aquarium is what makes the difference. Put on in a bowl and it might last 6 months (and die when the weather gets cold) Put one in a well set up aquarium, then it should live for many years.

Ian

Toss the bowl and get a real tank. Fish live in tanks, they die and suffer in bowls. Aim for at least 5 gallons but 10 is even better. The betta will also need a filter and heater. Before getting the fish you will want to cycle the tank for 4-8 weeks with a source of ammonia so the tank is ready. Get either live or silk plants but I don't think color really matters.

You can buy rock looking caves at the store or make one.

It should be ok with out a night light. Lights are really for live plants and to see the fish. Fish don't need them.

Do NOT EVER use a fish bowl.

How would you LIKE it if someone puts you in a SMALL CAGE and having you LIVE THE REST OF YOUR LIFE there in a CAGE?

I'm being really frank and serious here.