sick clown loach

Question
Hi there

I have a sick clown loach, had him for about 2 years and he is about 12cm long. He does not want to eat and is getting thinner and thinner. One day I found him breathing very heavily on his side and I thought he was a gonner but he has managed to pull though but still won't eat. i do have too many fish in the tank (250 litre tank, 4 bala sharks 20cm, 4 angels, pleco cat, golden gourami, 10 clown loaches) and am currently building a 2m tank to upgrade. I am doing regular water changes. I have a school of 10 clowns, the rest are all very happy and they only really want to eat blood worm (any ideas on what else they might eat). I have treated the whole tank with several meds. I first tried aquadene general aid, then sera mycopur, then aquadene gill, fungus parasite special. I have sterazin and will try this next. All doses i reduced the concentrations as i was concerned about the clown loach's in the tank as I have read they are susceptible to meds. I did see what looked to me like  worm in the tank yesterday, i did not get a long look as it was suspended in the water and got washed behind my woodwork. I would say it was about 4cm long and had a thicker rounded head end with a red tip and tapered thinner towards the tail. I would guess some sort of parasitic worm but have no idea of what it would be... Can you help i really don't want to loose this clown as he is my oldest and biggest. Thanks for your assistance. dave

Answer
if you treat fish wrongly it can also make them ill so i wouldnt treat them anymore until you know whats wrong..

do you have a smaller tank that you could seperate him into so he doesnt pass anything on?

i know they LOVE snails, mine live off of snails, thats all they will eat, also you can buy sinking pellets especially made for loaches..

i have a website link i can send you with all different illness symptoms and how to treat it but the link is at home and im at work, i will send it to you later (ask a follow up question)
good luck!