Which chemical in the Nit. Cycle is the most toxic to fish?

[fish-eyed-fool]

I would guess Nitrate, since it is chemically furthest from what is excreted by the fish.

So which is worse: ammonia, nitrite, or nitrate?

Or are they equally harmful?

[Scotty]

For all practical purposes, Ammonia and Nitrite are both equally, and highly toxic to fish. Nitrate is much less so, which is a good thing since it tends to accumulate more, being the end result of the Nitrification process. It's still not good for your fish, and should be kept at a minimum through water changes. Think of it this way;

Ammonia & Nitrite = Anthrax
Nitrate= Second hand cigarette smoke

[fish-eyed-fool]

[quote:2532d28daf="Scotty"]
Ammonia & Nitrite = Anthrax
Nitrate= Second hand cigarette smoke[/quote:2532d28daf]

Nice analogy! Thanks.

Again, I was way off base.

[SGypsyMermaid]

the only way to learn is to ask--so ask away. :D