Andris,

I recommend reducing winter feed. Biological activity in winter temps is subdued and so may not be able to keep up with rates of feed.

You can control ammonia either by reducing feed rates or by increasing the C/N ratio of feed inputs. Fish need higher % protein feeds than allows for that however. So usually the Carbon is increased by separately adding sugars or starches to the water. This provides the additional energy required for yeasts, bacteria, and fungi to metabolize the ammonia. In a TP culture, this is food for the fish (even flocs are harvested and incorporated in feeds to result in zero emission aquaculture with no water change). But in trout culture ... probably not much help. If you want to know more about it google Biofloc Technology and see where this takes you.

Probably the best approach with Trout, a fish with more stringent water quality requirements, is to feed no more than can be handled with available water exchange capabilities. This might also require reducing the number and weight of trout one is trying to produce. Try to understand what your limits are and design within them.

It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers