6 month old oscar, 30 gal tank for now, no tank mates b/c he killed his pleco early on.

never closes his mouth, dont think he can.
he sucks a pellet in and blows it right back out.

water temp around 75-77'F
nitrate 20 ppm
nitrite 0 ppm
soft water
alkalinity 80 ppm (moderate)
pH 7

monthly water changes @ 50%
there is always wasted pellets floating around, my husband feeds him daily, 7-10 pellets
seems active, sometimes "sleeps" on his side, but not for long, no other abnormal activity.
he's our first oscar, only about 5-6 inches long, 6 months old

im concerned that the chronic open mouth is impeding his ability to eat. I will post a picture as well

we have 2 airstones and a large whisper bio filter
i cant get a pic right now, i have to resize it

Hi there and welcome to ofl.com.

yr water parameters seem to be ok,could you also tell us what the amonia tests are in yr tank.

at this moment im just speculating as i would be able to give u a more defnit answer once i see a pic.

50% monthly is not enough, rather try smaller water changes more frequent like 15% weekly as a whole month worth of poo annd un eaten food will defnit rush yr amonia levels sky high.

u also mentioned that he doesnt eat all his food give him 2minutes and what ever food is still floating around you should remove,uneaten food is a major cause of bad water quality.

anyway hope this helps a bit & pls post a pick so we can see yr Oscar.

oh i almost forgot to mention but u probably all ready know this but yr oscar needs to be moved into a bigger tank soon.

the 30g tank is to small if you keep yr oscar in a small tank his body might stop growing(stunting)but his organs keep growing and sooner or later his body cant handle all the pressure from the growing organs and then you have huge problem.

if possible attempt to get a 55gallon tank or 75gallon would be even beter

i will share that info with my husband and have him get a pic for me. i will def start more frequent albeit smaller water changes and removing uneaten food right away.

oddly though, just prior to water change, and it had been awhile, the levels were all spot on. that's what i dont understand. he's always been like that. there is no obstruction visible and he's of a good size and appearance...my husband feeds him, after night shift, so im never awake to see him eat, but i know there are tons of pellets floating around later in the day. i think we will try feeding every other day to see if that makes a difference.

i will def get pics up, im very curious for a diagnosis or idea, opinion, similar experience...i love the little guy and just want to be sure he's not sick or in pain from this...
thanks for the tips.

Only feed what you fish will eat in 3 mins. If any food is still floating around then you are feeding to much so remove the uneaten food and feed less next time

Is the mouth open all the time or is the fish opening and closing its mouth like it is 'breathing'

constantly open...
ammonia level was 0, after a big water change though...
here's his pics, he didnt like the camera much though

more

another, dont know how to post them all together:unsure:

or take a decent pic either

AND....done:side:

that looks very odd normally oscars gasp for air when oxygen in the water is not enough but this is constant movment of the mouth and gills.

ive occasionally caught my oscars have a quick yawn but never keeping the mouth open all the time.

does yr oscar seem healthy and happy and does he swim around alot and could u tell me the amonia levels in yr tank?

he seems happy and looks healthy otherwise...
all levels were within normal parameters before the water change, i didnt check ammonia until after the change, i was new to oscar care and was just trying to help. ammonia 0 ppm after i did a big water change...i just inherited responsibility for the little guy and gave myself a total crash coarse in his care, thanks to this site, most of all. ive not fed him in two days, this morning i tried to give him three pellets and he wouldnt eat them after 5 minutes so i scooped them out. he hasnt poo'ed since i changed the water either. my next step is some "treats" as posted in this site, but i will wait a few more days to make sure he's good and hungry. but, yes, his mouth is always open, it hasnt always been that way, he's 7 months old and was fine for the first 4-5 months. like i said, he wasnt my fish, so i didnt pay close enough attention to notice. but now that my husband is working very long hours, he is my responsibility, so i plan on taking care of him RIGHT. ive learned sooo much thanks to this site and my local pet store, but no one can seem to offer me an explanation....very perplexing....