So Kav - you didn't change water for a year and a half, you fed your fish twice a week...:22_yikes:
I don't know how it is that no one is saying it so plainly, but this is neglect on your part, plain and simple.
And that's why it's good that most places don't have "animal cruelty" laws that include fish. Because people are determined to impose their ignorance on everyone else.
In fact, not a single fish died, in that year and a half, nor the next year and a half that I intentionally kept up the same regimen, except one very old molly.
MOST people overfeed their fish, especially casual tank owners. Charicins simply don't need the thrice-daily feeding, or even once-daily, that the fish food sellers list on their products (in order, obviously, to get you to use more of their food). Even cichlids generally don't need more than one feeding per day, though their needs are much greater than charicins. In my main tank, I actually feed cichlid food once per day, but the community fish their separate food (as their mouths generally don't fit around the cichlid food) only every two or three days.
This is GOOD fishkeeping, my friend. Overfeeding is among the worst things you can do to a tank. I suppose if some of you are feeding your fish far more often than is necessary, then a routine water change is a very simple, though clumsy, way to compensate for that.
The fish may not have died, but neither do people in vegetative states. Fish obviously enjoy stimulus, and it appears you gave them none except for twice a week. What is the point of keeping an aquarium if you don't interact with it?
What is concerning me, right now, is the realization that trillions of fish out in the wild suffer from not interacting with people on a regular basis.
How can we do this to them? We all need to don SCUBA gear right now!
Oh, wait, that's right, I'm anthropomorphizing. In fact, fish don't need to interact with people AT ALL. They can feel normally stimulated without it.
That's as silly as the "you wouldn't want to have to breath your own pee" comments. Fish are not people. Many fish eat each other's poop on purpose, in the wild, because it's good for them. I wouldn't want to breath water, AT ALL, urine or no. Fish are not people.
Metabolites build up in aquariums, plain and simple, and they stunt the growth of fish. Perhaps they cause other harm - all we have observed is that a stale tank yields stunted fish. Raise a tank full of guppy fry with no water changes next to a tank full of guppy fry with small, daily water changes. Pack them both full of plants and sponge filters, maybe even use high a quality GAC like Chemi-Pure to cope with pollution. Feed them identically. See which one has more runts and S curved spines.
You say that, but have you actually done it? Neither has anyone else, here.
I'm with the Mod who suggested that you've never kept "difficult" fish. I think this just proves how tolerant the community fish you kept are, just like those poor crape myrtles which get butchered year after year...
Since marine tanks and cichlids are not difficult, you're correct: I avoid difficult fish. I already said that. And have said many times that some specific fish (I keep using rams and seahorses as examples) need very special care, perhaps including weekly water changes.
But people who take that and start insisting that everyone must, all the time, impose weekly water changes on all tanks have absolutely nothing on their side.