When I was a kid, my neighbors decided to not open their pool. Of course, in no time it was dark green.
One night after a really good nite of channel cat fishing, we threw in about 10 of our biggest ones. They lived for at least 5 or 6 years. After that, I moved on, so they may still be alive for all I know. Every once in a while the neighbor kid would "fish" for them, and then throw them back.
If catfish do not appeal to you, maybe get some Koi. But you will never be able to enjoy them, because the water will be pitch black.

No, you don't have to open it but when it is finally opened, expect a major cleanup. The algae will likely grow like kelp.
You will also probably have phosphates that will need to be treated.

Well, since the pool has the hard, tie-down mesh cover I'm not too worried about kids tossing fish in the pool. ;)

Since we do use a professional service to open the pol, extra algae will be their problem. I was more concerned about some possible damage to the pool surface or pipes if the pool isn't opened.

Thanks for the reassurance. :-)

Shucks, I really thought you would like my catfish pond option.
Also with no chlorine, mosquitos will love the place to lay eggs.
You can probably have it filled in for your $2000 yearl expense, and then be done with it.
Just be sure to disclose this if you ever sell.

The mosquitoes would be a really big concern... if my brother didn't own a pest control company and spray monthly.

I would LOVE to fill it in. I've been outvoted every year, however.

Wow, the smell was something I never considered, Renee. Thanks so much for bringing up that point. I guess we will have to reevaluate.