By silting up do you mean that there is suspended dirt in the water?
The fish might be stirring up the dirt that has settled to the bottom. Bottom
feeders are good at hovering up stuff and spitting it out again.
Not sure about your filters but sometimes you can add a layer of cotton or poly
batting and it will catch a lot of dirt. Do watch it closely to make sure it
doesn't clog up and send water over the side or out another way.


kathy :-)
algae primer
http://hometown.aol.com/ka30p/myhomepage/garden.html