Heavy gravel/plant movement kills fishes?

[enhanzed]

does heavy plant/gravel movement causing alot of dirt/sediments etc to be stirred up cause death to fishes ?

Cause i removed quite a number of dead & dying plants , moved them around quite a bit and caused alot of sediments to be stirred up . couple of days later 3 guppies , 4 sucker fishes died ,water lettuce dropping their roots but all Oto's and cardinals are ok .

[xaine]

There's lots of waste in the gravel, in any form, the ammonia, nitrite gets stirred up, might be a possible cause to the toxication of the fishes.