This is a complex issue. Reducing it to a recipe is a good rule of thumb to get going, but all fish and tanks are different, the amount of food to keep fish healthy going into a low flow tank for fish will be different than a high flow tank. Also, different fish need food at different amounts (and often different foods). The recipe eventually can get reefers into trouble because it has nothing to do with the actuality of living in your tank.
I agree that there is probably not a formula to get it 100% accurate. My thoughts were more around defining a baseline to determine if one is far off, i.e., significantly over or under that baseline, to put some light on this more nebulous topic of fish feeding.
Being under the baseline seems easier to determine than over, as the fish would get visibly too skinny I assume. I also assume this is what you are referring to get reefers into trouble, by under feeding the fish as a result of following a potentially insufficient food supply calculation.
Being over a baseline the more difficult part, hence posing the question on a complex and apparantly emotional topic

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I had in my brief write up that different fish might need different amounts, i.e., Anthias and Tangs might need 50% more food than some other ‘less active’ swimmers (3% vs 2% of the body weight).
What I did not include was the food composition, protein content, fat, fiber. This would also be different by fish type, e.g., lower protein and higher fiber needs for tangs, higher protein and lower fiber needs for anthias.
I wonder if insufficient quantity is really the issue or rather quality. So feeding what the fish needs vs feeding a ton of food appears to be more important. You could feed a lot but not the right things (different from variety).
High flow vs low flow was not on my radar, thank you for bringing this up. So a high flow tank would need more food in your opinion, correct? Interesting to think about what constitutes a high flow tank, but probably an SPS vs softie tank would be the broad categorization.
The starting body weight/compisition matters, and that matters for folks that say somtimes they don't feed their fish for a week or two. What they snack on in the tank also matters, as does the amount of exercise the fish get from flow or flow changes.
Have not heard someone saying they do not feed their fish for an extended period, and would not be supportive of this either.
Thank you - I was not sure. But from all the comments, I do not see this mentioned as a broad concern. So how is this risk being addressed? In my case, I do believe I have fish that overeat.
You also need to think about how much of your fish food is for corals.
Can you elaborate why this matters? Or is this simply saying that coral food added to fish food does not count, which seems logical. And is fish food not mostly coral food? I feed corals separately a couple of times per week.
I get skinny fish in the lab tanks when I don't pay enough attention for various reasons or the auto feeders have clogged. Its not great, and I fix it when I see it.
I aim to have autofeeders on all my tanks for the fish that don't need frozen. In there I put coral foods, pellets, and flake (I love a good flake food, and the NPS can catch the flakes). I feed frozen intermittently. I would like to be feed it evey other day, or every third day.
Some interesting nuggets in here: There are some fish that do not need frozen food? Can you provide an example? Or which fish need frozen food? And those that do need frozen food, why is it ok to only feed them every 3 days?
Also, I think there is good (quality) flake food as you say - but I did not know that the NPS benefit from them.
There is no way I can give you direction on animals I have not seen. If the fish are thin, feed more, if they are too fat, feed less.
As I said in the title, feeding more is easy, feeding less (or rather an adquate amount) seems harder to do unless all fish appear trending in the same direction. Relying on fish shape only seems to simplify this topic too much but the majority seems to gravitate to this.
I think chasing numbers is generally not good, but worse when making feeding choices - you don't stop feed the baby less because you don't like changing diapers.
I know you think that way, and there is no real argument against this. But ignoring numbers feels equally uninformed these days, and makes it harder for others to enter the hobby who cannot rely on 'gut' instinct and anecdotal guidance.
Re the diaper analogy - I am not sure if there is really no value in not letting the fish swim in highly polluted/high nitrate (and phosphate) water. But those with high nutrients will probably argue against that

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I sincerely appreciate all your insight!