A short, but very interesting study in ammonia eating bacteria, and how frequency of feeding affects ammonia rates in water.  
 
..."Feeding leads to a peak in the ammonia production. For the symbiosis between fish and bacteria, it is better if the ammonia production is more constant. It is therefore better to feed often with small amounts than with large amounts once or twice a day. The bacteria -- and therefore the fish -- benefit from this feeding tactic. Nearly all organisms benefit from constancy."
 
New type of symbiosis: Bacteria eat ammonia in fish gills -- ScienceDaily