Fish expiry date

We have two aquariums of fish that used to belong to my brother. We've had them for a couple of years and in one of them are some brown danios (I think?) that have a very short life span of only two years. There were about 8 to start of with and since it's past two years now, they have been getting old and expiring one by one.

There are only two left now.


Well sort of.

There is a third one that is really old, and you can tell by how much their spine droops - a sign of this species' old age - this third one has a very bent spine that has been getting more and more bent. And eventually it stopped being boyant and just rested on the aquarium floorbed. A week after that, it just lay there gasping. I thought it would die any day. But yet, the days turned into another week, and it still hung around on the ground gasping.

After two weeks, I tried sprinkling lots of food around it's mouth so it could at least gasp, and eat. But it didn't seem interested in the food. I was pretty sure in another few days it would be gone. But a week later, it was STILL alive.

By three weeks later, it was really pallid coloured, and from afar it looks dead. But then when you go up to it, you can see it's still 'breathing' and gasping.

It is now four weeks later and it is beyond a joke. I even saw it spasmically swimming in bursts a few nights ago. And it is all pale beyond life, and sickly, and sallow looking, and I'm sure it should have been dead four weeks ago.

It's a ZOMBIE FISH.