I've had a few and YES I have learned by now.
Growing up, we had a goldfish in a bowl, it lived 7-8 years.
5 gallon bow front, 1st stocked with 5 cardinal tetras and 2 green Cory cats. After everybody passed away, restocked with 2 male mollies, these didn't last long either
Got smarter and stocked same tank with a female betta, 2 ottos and a blue mystery snail. This combo somehow worked for months w/o water changes and not testing the water.
More recently, I had my 10 gallon with a small breeding group of blueberry shrimp who cost $10 a shrimp and weren't 1/4 inch long, so kinda pricey. I had added a male betta and he proceeded to hunt down about $80 worth of shrimp.