Ok....that's where your nitrates went.... you changed them all out.
Here's what I recommend regarding your canister filter.....let it establish. Dont clean it for a few months.
If you notice that the flow slows down.....or it looks like your water isn't filtering properly....or your nitrates...
Ok....that sounds good.
What was your source of ammonia?
Did you see nitrite rise and fall back to zero?
I hope you don't mind the questions. You don't have to answer them.
If you want to just leave it at cleaning the canister then thats fine.
Your low level of nitrate is alarming and...
Oh no.....how long ago was that?
You said a couple of months...does that mean 2 months? 5 months?
By that I mean, how long ago did you complete this "fishless cycle" and how long did it take to complete?
While you're doing that....
Usually I know that its time to clean my canisters when my nitrates start building up too quickly after a water change....if you go too long between cleanings they turn into nitrate factories.
Is it an API test kit?
Are you following the directions on the nitrate test correctly? You gotta shake the mess out of bottle #2 and make sure it's mixed really good.
If you don't it will give you a false zero result.
If you have good mechanical filtration and prefiltration you won't have to clean them as often.
I crack open a canister probably once every 3-4 months and they stay pretty clean....just squeeze the mechanical stuff out and keep going.
Im more concerned with the 0 nitrates....what's up with that?
I'm satisfied that your tank is cycled to at least handle 1ppm of ammonia in 24 hours.
Are you sure that you don't want to try 2ppm?
I mean, here's the reality of it...
You're going to add a small school of corys, then a pair of rams.
Later on maybe a few of something else small.
What else is in the tank with him?
How big is the tank?
This fish wasn't sick....his fins are perfect.
I'm almost willing to bet money that he lost a fight.....went to hide....got stuck then died.
And possibly kept getting beat on after he got stuck.
The marks on his side are from the battle...
Wow....alot of "info" being shared over on that thread.
Ok...so after reviewing both threads there are a few things worth noting.
The puzzling nitrate levels.
The "stalled" ammonia.
The color blindness.
Perhaps the numbers being shared might be a bit "off".
MidWestAquarium if you don't...