As I have stated, mammals (those of you thinking that YOU eat several meals a day-> you are a mammal) and other endothermic organisms have a very different form of digestion and assimilation than an ectothermic organism. I will also add that Vertebrates are very different from invertebrates.
Also keep in mind the differences between adults and juveniles. Those of you feeding your grow out tanks several times a day... keep doing that! Adults do not have the same needs as juveniles. As fish mature the rate of assimilation lowers considerably and metabolic energy demands are much lower.
I doubt that the entire articles of these can be read without a university subscription, but the abstracts are meaningful. Nearly all studies of this topic are done with juvenile fish and are done to increase growth rates for aquaculture purposes.
This states that for
juvenile sunfish age zero, optimum feeding frequency was 3x a day. They tried feeding from 1-4 times daily.
This is a
catfish study that fed from 1-24 times a day and found optimal growth at 2x a day.
This article done with
adult fish looks at the metabolic energy used in digesting food. It measured metabolic rate by measuring oxygen uptake from the water. It found that each meal a fish consumed caused an increase in its energy demands that lasted from 37-39 hours, peaking between 1 and 6 hours. During those peak hours, food is digested, but can't be assimilated. If its not assimilated it just passes through the digestive tract. If you shut anabolism down for 1-6 hours every time you feed your fish, do you really want to feed them 10x a day?!?! Anabolism is a slow enough process, no need to shut it down for 80% of the day!
And to show you that I am not biased... This study done with
trout fed from 1-6x a day found no significant differences between groups. "The general lack of response to feeding frequency was attributed primarily to the low metabolic rate of trout and to the characteristically slow rate of food passage in the digestive tract."
I hope that helps.