Feeding Fishes- Belly Filling Thanksgiving Special
In honor of this week’s uber American Holiday of Thanksgiving I thought it would be fun to talk about feeding your tank. Feeding & Foraging has been a big part of my career and studies for over a decade now. Analyzing the amount of food consumed by reef fishes was something I studied years ago thinking it was a passing assignment. Little did I know how many people would still be asking me about this topic years later.
How much should I feed my fish, and how often?
I’ve been emailed these questions dozens of times. While at any conference, symposium, and club meeting I still find myself addressing these issues. I’d like to give you some of the basic husbandry (factual) and recommendations (experience) that I’ve found to be successful for many hobbyists.
How much food can your fish eat? “A fish’s stomach is as big as its eye, and it fills three times a day.” That was the mantra for when I was in school. I heard several professors say it. It seemed so overly simplistic to me for many years. It completely ignores gut length, nutritional analysis, feeding frequency, herbivory vs. carnivory, and most importantly the actual size of the fish and its eye. However, 10 years later here I am seeing the value in that simple saying. When dealing with common reef fishes, I guess the simplistic rule does have its place. Part of the purpose of that saying (I am inferring) is that there isn’t a purpose in feeding more food to a fish than will fit in its stomach.
For the “common” or “average” reef fish the stomach occupies a small portion of the fish and its capacity is certainly limited.
As for the three times per day; that has been repeated in literature more times than I can count. In fact I often joke about fellow author and friend Scott Michael because it seems to me that he recommends every single reef fish being fed three times per day on every species in every book he’s ever written. My question to Scott has been “other than Scott, who is home to feed their fish three times a day?” Maybe I’m the only one who goes to work around here, I don’t know. Regardless, it is certainly true that most fishes spend a good amount of time looking for food and picking at food.
My best recommendation is that you can’t over feed your fish. I think most people who are reading this are familiar with my husbandry techniques and my belief in heavy feedings for fishes. I completely understand and believe in the benefits of heavy feeding including: growth, reproduction, vigor, coloration, responsiveness, etc. There a few exceptions of fish that will gorge themselves (lionfish come to mind) but the majority of reef fishes will do better in captivity when frequently fed. Since most people are unable to frequently feed their fishes a constant grazing food source is very handy. My aquariums have always had crops of macro algae as well as nori sheets constantly added to the aquarium. Keep in mind that a fish in the wild always has a few things on its mind: what can I eat, what can eat me, when can I mate. (Two of those items sound awfully familiar as a human.)
Two things influence a fish's feeding strategies more than anything else- locomotion and dentition. While locomotion is a whole topic in itself, I thought dentition may be worth visiting here. You can tell a lot about what a fish eats by looking at its mouth. The structure of teeth, number of teeth, size of oral cavity, etc can help in understanding the prey items a fish will consume. For hobbyists, most of this is overkill. I love it, but all you really need to know from this perspective is does your fish eat: meat, algae, plankton, other fish, inverts, or a combination of items. Particle size is a little more important because your fish must see the food, recognize it as food, and still be able to consume it. I recommend taking your frozen food and trying to chop it up into differing sizes and observe which fish select each size. We've all seen fish literally bite off more than they could chew. Meanwhile particles that are too small eventually settle in the aquarium and become coral/invert food in ideal conditions or decaying waste in other situations. Uneaten food is a real problem for the aquarium.
So What’s The Problem?
It seems so simple up to this point. Feed your fish. Feed them lots. Feed them food (more to come on that in a later article). Feed them often. So why all the questions and emails? While it is nearly impossible to overfeed your fish, it is very easy to overfeed your aquarium! This leads to the topic of filtration which I’ve published numerous articles to detail, yet still can’t find a solid set of advice to suffice. With the dozens of tanks that I’ve seen in a less than perfect state the vast majority are not problems with being underfed, but instead are problems of a lack of filtration. I’ve seen (and have even personally owned) tanks that use very minimal feeding with great success. Even several tanks that were very healthy while being fed once per two weeks. These natural-type systems offered constant grazing and are a favorite of many expert aquarists. However one could argue that these tanks would be even better with higher feeding levels… assuming the tanks can handle it.
A few final words on filtration. While that will be an entire upcoming topic just think about this - what goes in must come out. So if you have a little nano, and you feed it a lot, three times per day... just do a water change every few days for me, okay? And if you have a large tank with some serious flow and you feed it frequently, get yourself a large skimmer, and be sure to change our those filter socks every couple days for me. Thanks!
Nearly all of your reef inhabitants will do better with frequent feedings of a multitude of foods…. but first you need to make sure your filtration processes are already running at that high level.