I've got a 180l freshwater tank with numerous fish, we have had this tank for around 9 years and i can tell you that whilst a lovely and addictive hobby its also a distressing and annoying thing to have.
we have been through several mass extinctions for several reasons like heating braking down when we where away on winter holiday, kids on 2 occasions decided the fish looked particularly hungry so fed them a kilo of food, bizare unknown fungus and bacterial infections, 1 fish we had ( a supposedly relatively harmless and fragile black tetra) managed to somehow survive every mass extinction then one day just flipped and proceded to kill almost all the other fish 3 times its size.
with all the testing with different filter options, plants, replacement fish, energy useage time spent on cleaning and feeding, testing water etc I think i might have spent more time and money on it than my bike
saying all that and looking at it now, its a mess and really needs to be cleaned
but for the 15 minutes i spend looking at it a day and laughing at the nature of the dog like behaviour of clown loaches its well and truely worth it