Aquarium fish

I didn't have much luck with fish. Here's what happened.

I've had several kinds of fish. I've had Neon Tetras, Blue Long-Fin Danios, Bloodfin Tetras, Albino Corydoras Catfish, Spotted Cory Catfish, Otocinclus Catfish, and two little under water frogs. I first got neon tetras, danios and a frog. A few days later a tetra and the frog died. I got two bloodfin tetras, the cory catfish, and another frog. After a while, the albino catfish died. I was going to get another cory catfish but the spotted cory died too. The frog died too. So I got two otocinclus catfish instead. They died when I was quarantining them. The neon tetras died too, so then I just had two danios and two bloodfin tetras. One of the danios died. Right now I just have two bloodfin tetras and one danio. :(