Clown loach

[Thomas Douch]

My clown loaches are lying up against my filter between the filter and the glass should I be worried ?

 

[butterfly_koi]

Not unless there are signs of sickness. Not the same type of fish but I have a Bumblebee Cat that likes to wedge himself between the glass and the heater that's his spot and that's where he likes to sit all of the time.
Just double check the water levels, Ammonia, Nitrite, Nitrate & Ph
If everything is fine and the fish is acting normally I wouldn't worry too much.