Pets are good, because they teach children important lessons about life, the main one being that, sooner or later, life kicks the bucket.

With me, it was sooner. When I was a boy, my dad, who worked in New York City, would periodically bring home a turtle in a little plastic tank that had a little plastic island with a little plastic palm tree, as is so often found in natural turtle habitats.

I was excited about having a pet, and I’d give the turtle a fun pet name like Scooter. But my excitement was not shared by Scooter, who, despite residing in a tropical paradise, never did anything except mope around. Actually, he didn’t even mope “around”: He moped in one place without moving, or even blinking, for days on end, displaying basically the same vital signs as an ashtray. Eventually I would realize — it wasn’t easy to tell — that Scooter had passed on to that Big Pond in the Sky, and I’d bury him in the garden, where he’d decompose and become food for the zucchini, which in turn would be eaten by my dad, who would in turn go to New York City, where, compelled by powerful instincts that even he did not understand, he would buy me another moping death turtle. And so the cycle of life would repeat.

I say all this to explain why I recently bought fish for my 4-year-old daughter, Sophie. My wife and I realized how badly she wanted an animal when she found a beetle on the patio and declared that it was a pet, named Marvin. She put Marvin into a Tupperware container, where, under Sophie’s loving care and feeding, he thrived for maybe nine seconds before expiring like a little six-legged parking meter. Fortunately, we have a beetle-intensive patio, so, unbeknownst to Sophie, we were able to replace Marvin with a parade of stand-ins of various sizes (“Look! Marvin has grown bigger!” “Wow! Today Marvin has grown smaller!”). But it gets to be tedious, going out early every morning to wrangle patio beetles. So we decided to go with fish.

I had fish of my own, years ago, and it did not go well. They got some disease like Mongolian Fin Rot, which left them basically just little pooping torsos. But I figured that today, with all the technological advances we have such as cellular phones and “digital” things and carbohydrate-free toothpaste, modern fish would be more reliable.

So we got an aquarium and prepared it with special water and special gravel and special fake plants and a special scenic rock so the fish would be intellectually stimulated and get into a decent college. When everything was ready I went to the aquarium store to buy fish, my only criteria being that they should be (1) hardy digital fish; and (2) fish that looked a LOT like other fish, in case God forbid we had to Marvinize them.

This is when I discovered how complex fish society is. I’d point to some colorful fish and say, “What about these?” And the aquarium guy would say, “Those are great fish, but they do get aggressive when they mate.” And I’d say, “Like, how aggressive?” And he’d say, “They’ll kill all the other fish.”

This was a recurring theme. I’d point to some fish, and the aquarium guy would inform me that these fish could become aggressive if there were fewer than four of them, or an odd number of them, or it was a month containing the letter “R,” or they heard the song “Who Let the Dogs Out.” It turns out that an aquarium is a powder keg that can explode in deadly violence at any moment, just like the Middle East, or junior high school.

TRUE STORY: A friend of mine named David Shor told me that his kids had an aquarium containing a kind of fish called African cichlids, and one of them died. So David went to the aquarium store and picked out a replacement African cichlid, but the aquarium guy said he couldn’t buy that one, and David asked why, and the guy said: “Because that one is from a different lake.”

But getting back to my daughter’s fish: After much thought, the aquarium guy was able to find me three totally pacifist fish — Barney Fife fish, fish so nonviolent that, in the wild, worms routinely beat them up and steal their lunch money. I brought these home, and so far they have not killed each other or died in any way. Plus, Sophie LOVES them. So everything is working out beautifully. I hope it stays that way, because I hate zucchini.

Dave Barry is a humor columnist for the Miami Herald.