I was wondering if there is any symtomes of sickness in him ! these few days he doesn't seem to be too active for some reason... he use to be more active i was wondering if its the temperature that is making him slow down.. before the temperature was up to 80F because to treat new fish and to prevent any parasites ...
but now its back down to around 75 degrees .. he didn't seem like to eatting much on the glass .. i'm not sure if he does at night but he's just stays in his favorite spots .. and not much movements... he use to eat the food i have on the clip too but now he's not eatting much...

oh and
nitrates 20
nitrites 0
amonnia 1

my guess is that it's the ammonia, do a waterchange and see if that doesn't perk him up. Also what are you feeding him? Any vegatables? Sometimes I don't see my BN that I've had for three years now for a day or two he just likes to come out at night and hang out in the crevices of his driftwood

yeah .. i try to stay low on those 3 things ... he use to be active .. i'm not sure if he's too full eatting the goldfish food ?!??!?! i feed him algae food( usually eatten by goldfish)... lettus .. cucumber ... zuccine ( not anymore cuz it creates a mess ) ... watermelon... i duno what ever it is on the clip ^^
he use to fight for food against the goldfish but now he's just on the driftwood... don't know wuts wrong with him ?!?! hope everything is good

Like I said I would do a waterchange and stop feeding him for about a week, he should come around, I know that when my guy stops cleaning my algae I stop feeding him and he eats the algae then I start feeding him again, I would feed him zucchini again though do it right before a waterchange if it gets too messy. How often are you changing your water?

well i do it almost twice a week .. depending on my avaliablity.... i don't think i'm going to feed zuccine ... i rather give some other types of food... its not just the pleco that is making the mess its the goldfish ! ... i just did another one today .. i had a water change 3 days ago .. even if i feed the goldfish eats them all .. not exactly feeding the pleco ...
i feed twice a day mainly one meal veggie and one meal hikari lionhead... but as i say the goldfish eats them all ..

Humm, I wonder why you have an Ammonia reading? weird. About the goldies getting the food someone gave me a great tip, a couple of years ago if you feed the pleco when you turn out the lights the pleco is a lot more apt to get the food.

yeah thats wut i thought too !!! weird reading ..but now i checked again its 0 ... i tried it too but too dark to see if it actually made a differents ..my goldies have a sensitive nose ! when they smell food they all peck on it like mad !! ^^ love those guys but poor bristlenose ! hehe but i still feed him veggie ..

It could also be your nitrates 20 is quite high for both goldfish and pleco's I'd do a large water change 60% to get them down. High nitrates and ammonia in your water can be indicative of overfeeding, which I'm sure we've all been guilty of at the time. Hope your fish is on the mend soon!

hahaaha i was wondering is there over feeding for veggies ???

Check your tapwater readings from a cup and see if nitrate is the same as the tank. A reading of 20 is nothing to be worried about.
How big is the tank, how many fish and sizes?
Plecs sleep a lot through the day and are active at night. I would drop a couple of the pellets in while the tank is dark and as long as the belly of the fish isnt concave then your plec is fine.

You also said in your first post that you had raised the temp to treat new fish. Did you add any sort of medications, salt, etc that you normally don't have in the tank when you were treating?