This is going to sound a bit smug but I think fish/plant keeping is about the toughest challenge there is out of the normal range of pets. We're part vet, science professor, artist, chemist, environmental director and general workbody.
The garden out the back I put some ferts on and water. That's it, fruit arrives and I guess pruning/netting. I know it's more complex but most of my garden problems I can solve easily.
Love other pets and love when the cat sits out the front for a pat but this is a greater challenge, although not tinkering and stopping from buying more stuff is a downside (sort of ?).
Oh yeah, and there's great forums like this one where i can talk about aquarium stuff and not have to shake people awake or promise bribes...