EmoKittehXD wrote:like i said they are quite small and he will be staying there until he can go into my aunts pond this spring. i'm raising him for her for breeding. I am in progress of setting up my 29-gallon right now so i can move the shubunkin and or koi. they are both about four inches long and the plecostamus is about one inch.
i do water changes every other week, and i'm not sure about the parameters. last time i got it checked, a few weeks ago, the ammonia was slightly higher than it should be, and i did a partial water after that.
i feed him koi pellets, in all, for all the fish i normally give around 6, but i forgot to feed him two nights ago, due to family issues and stess (believe me, its not a normal occurence or else all my animals would be dead) so i gave them eight last night.
The pellets contain
Crude protien min. 35%
Crude Fat min. 5%
Crude fiber max 4%
Moisture max 12%
Ash Max 10%
Poshphorus 0.8% min.
I can list all the ingrediants, but it will take a while. let me know if you want me to.
The pleco should not be in with the goldfish unless it is a bristle nose or rubber nose pleco. Not only will the pleco try and eat the slime coat off of them but most plecos can get really big and will need a bigger tank I believe. Another one of the members here who have knowledge on them would be able to assist you better with that.

With a Koi and shubukin in a 40 gallon you should be doing at least weekly water changes of 60% or more. Do the pellets float? If they do try and soak them. I think what is happening here is the waste build up can effect their swim bladder and if they are gasping at the surface for food then the air can get inside of their bellies and cause issues as well.
Also its ok if you miss a meal or two. Fish can survive quite awhile without food so don't over feed. That will only make the waste go up in the tank and make things worse.
If you can get the water checked that would help greatly. If you take it to a pet store be sure to use a glass container as plastic can mess with the results. Get the number results and not just and "its ok".
So more water changes of 60% or more.
Starve for a day or two, then feed the peas(one pea per fish). See if that helps.