Pale inactive clown loach

[skimmy]

I have a 55 gallon tank with 4 clown loaches and some other fish (i plan to upgrade as fish get larger) I recently ran into a problem with 2 of my loaches. They are all about 3 inches in length but 2 of them appear thinner and paler than the others. Out of the 2 pale ones, one is skinner then others and during feeding times i don't see him eat even if food falls right on his face, while the other loaches go into a feeding frenzy. He is always by himself while the others school and his gills are moving rapidly but he doesn't go to the surface to gasp for air. My nitrite, nitrate, and ammonia levels are all 0 and I do a 30% water change every 10 days. He is very inactive to the point where last night he was in the territory of my red tail shark and the shark (who is rather docile) tried to push him out but the clown wouldn't even swim away but just stayed right there until the shark gave up and swam away. What could be wrong? I've seen pictures of the "skinny disease" but the clowns in those pictures seem to still have their colors while mine is still pale and he is not as horrendously thin as the ones in the pictures. Any suggestions would be greatly appreciated. Thank YOU

[Tinman]

Increase your O2 levels by adding a power filter blasting the surface. This will increase activity and color. Clean your gravel and as far as the skinny that has been addressed on this site and is a different problem . A "skinny " loach will eat but not gain so if its not eating you must address that immediately . Increase your flow and lower the water level some to make your filters splash more if they will still work that way.

[chefkeith]

Lethargic fish usually do have something wrong with them. It's very difficult to say what.

Have you ever treated the fish for internal parasites or bacterial infections?

When a fish doesn't eat, it's often a sign of a bacterial problem.
If you quarantine the fish in question and give them a dose of antibiotics, it may cure them. I'd probably de-worm them also with some Prazipro because internal worms can cause the bacterial infections.
For antibiotics, you can use Maracyn I & Maracyn II in combination.

Like what Tinman said also. Increasing Water flow and increasing oxygen always helps.

[skimmy]

should i use a half dosage for the antibiotics since i'm using it on loaches or will the full dosage work fine?

[chefkeith]

Full dosage.

[helen nightingale]

i am not sure about your water test readings. i would expect to see some nitrAtes. what type of test are you using (liquid, strips...), and have you checked they are still in date?

i think Tinman and Chefkeith have given good advice