Hideing Corys

[dsgreat3]

Yesterday i bought 2 bristle nosed catfish and 4 red and orange corys (im not 100% on their real name) after geting them in the the tank they swam around quite hapily but spent most of their time at the back like all new fish tend to do.
in the evening i went down to check on them and could only spot 2 of the 4 corys but presumed the others must be hideing and so left them to it it was only later did my mum spot that all four were now stuck beheind the filter.
I have a fluval u2 and because it sits back off the glass and their is a large hole in the mount they were abble to get in but im not sure if they could get out it may just be that their is food back their that they want or they could be hideing but either way i dont want them back their their very nice looking fish and it eliminates the whole point if i cant see then
They are in a comunity tank with neon's endlers and guppys the tank has been establied a year and a bit an its only at about half its capicity and their are pleny of plants
At the moment the filer is off the mount just suspended in the water by a air tube clip on its wire so they can swim freely beyheind it bit i dont want to keep it thei way as it looks crappy

Why are they going back their?
Is their anything i can do to stop them going back their?

Your help is most apriciated thanks for reading

 

[snowflake311]

They need time to adjust to the new tank. Give them time keep the lights off for a day and they should settle in.

 

[racegoer]

I have Pygmy Corys that love it behind the Fluval 2 and I have also seen the Cherry Barbs there as well. I tipped mine off at an angle for a while but realised that they had plenty of room to get out and it was better to have the filter at the proper angle for water movement.