The intricate process of feeding

Fish is a term that aquarists are intimately familiar with. However, it’s a broad term that groups 60% of planet Earth’s entire population into one basic category. Roughly 30,000 species fall under the moniker “fish” and many are so different from one another, it would be difficult for the un-trained eye to tell they are from the same animal group. Deep sea anglerfish males latch onto females for the entirety of their lives, appearing like a small overgrown appendage; while flying fish soar for great distances on surface water air currents. Yet, both these animals are “fish” in the basic sense. Then there is the argument that exists with cartilaginous fish. These boneless animals are lumped in with vertebrates, even though from an evolutionary basis they deserve a category of their own. From an evolutionary perspective, tuna have more in common with humans than they do cartilaginous fish (sharks, rays, etc).

The point, fish is the most diverse animal classification on Earth. Even within our aquariums, there can be great diversity from one species to another. Some aquarium fish inhabit shallow coral reef lagoons, while their nearest tank mate inhabits surge zones, endemic to reefs thousands of miles away. Another species may inhabit depths in excess of 600 feet, living in near total darkness on a reef at the other side of the world. Some fish have mouths that face the substrate, making it easy to slurp up food as it rolls across the bottom. Others have upturned jaws, which allow them to pick food off the water’s surface. Various species have small mouths with a single row of teeth, designed to scrape algae off rocks. Even more have mouths placed in the middle of their heads, meant to pick plankton from the water column.

With such a diversity of animals within one family and so much diversity existing in one aquarium, it’s hard to believe that we feed all these animals the same thing. Some aquarists utilize a single pellet, frozen or prepared food and accept that it is appropriate for a group of highly diverse animals. Feeding a marine aquarium isn’t just about ensuring that every animal has adequate nutrition, but it’s also about ensuring that every animal is presented with food in an appealing manner. You wouldn’t serve a steak by placing it on the floor. What’s appealing to a bottom feeding Harlequin tuskfish may not remotely entice a mid-water feeding anthias. Nutrition and feeding is often where our success as marine aquarists both begins and ends. Proper nutrition can prevent disease, increase captive lifespan and ensure health in every animal within the aquarium. Yet, it’s been relegated to the category of aquarium chore, one that many aquarists have chosen to automate. Feeding isn’t something to be treated as an afterthought and while marine fish foods have improved greatly over the past few years, it still requires planning and implementation on part of the aquarist.

A feeding routine:

Long ago, when I first ventured into the world of marine aquariums, I tried the blanket feeding approach administered by many. A few of this flake, a few of this pellet and maybe some frozen foods here and there. My aquarium background was the realm of New World cichlids and Discus breeding, so I was accustomed to playing with a variety of foodstuffs. Blanket feeding didn’t work in the marine environment, that was apparent. So over my nearly 20-year career as a marine aquarist, I’ve been refining my feeding routine.

When I tell fellow aquarists how long I spend feeding my tank their usual response is, “Why?” Between three daily feedings, I spend about two hours ensuring my fish (and other animals) get appropriate meals. The importance of feeding is overly underestimated among mainstream hobbyists. First, fish are just one life-fo

rm within the tank that needs fed. There are a host of micro-organisms in the sand-bed, refuge, live rock, etc that also need food. Cleaner organisms often cannot survive on naturally occurring algae alone, so they too need fed. Corals of various species often fare best when fed on a regular basis and there is diversity in what species require what food. Being mindful of each organism’s nutritional feeding needs takes time, but is one of the cornerstones of successful reef keeping. Once you’ve established a feeding routine, it may need tweaked or altered from time to time, in order to account for any new species.

Step 1:

This first step in establishing a successful feeding routine is making a comprehensive list of all the animals within your tank. This is best done by separating each species out under a heading of what type of species they are and how they accept food. As an example, I’ve used fish from one of my personal reef aquariums (a 250 gallon tank), along with invertebrates and corals. This list doesn’t have to be overly complex, but enough so that on paper the aquarist has an idea of what needs done to ensure every organism is fed.


· Zebra Tang (Herbivore/mid-water to bottom feeding omnivore)

· Red tailed tamarin wrasse: (Mid water plankton feeder, rock scrounger, small mouth)

· Lineatus wrasse: (Mid water plankton feeder, rock scrounger, moderate mouth)

· C. earli wrasse: (Mid water plankton feeder, small mouth)

· Blotched deep water anthias / O. borbonious: (mid-water plankton feeder, large slightly upturned mouth)

· Black tang: (Herbivore/ mid-water rock picking omnivore)

· Three (3) barrier reef chromis: (mid-water feeding omnivore)

Starting with fish, a lot can be concluded by this simple description. First, fish usually accept food from the area of the water column that their mouth is facing. A down-turned mouth means the species is likely to eat off the bottom. A mid-facing mouth means that are likely to grab food in front of them, right out of the water column and an upturned mouth means they are likely grabbing food from the water’s surface or in the water column just above them.

The first thing I can deduce is that having floating food-stuff is worthless for my fish. All of them either accept food from the middle of the water column, or scrounge fallen food off the rocks. To limit waste during feeding, it’s vital that all the foods sink, with some falling slowly and others remaining partially suspended in the water column. Based on this, along with the fishes’ dietary needs a mix of fin-fish chunks, squid chunks, mysis shrimp and fish roe seems like a good feeding approach. Some of the fin-fish and squid is heavy enough to slowly settle out on rocks, while the mysis and roe will remain partially suspended for a few minutes, certainly long enough for the fish to grab some. The two herbivorous fish will need 24/7 supplementation with sea-weed.


· Various LPS corals that feed on small, microscopic fare

· Various LPS corals that feed on moderate sized fare

· Non-photosynthetic corals that feed on moderate/large fare

· Various LPS corals that feed on large fare

· SPS species that feed on microscopic fare

Rather than list out every coral species, it’s only necessary to make note of what the corals within your tank eat. This is easily detected, simply by looking at the size of the coral’s mouth and watching each species behavior during feeding. Corals with large polyps and mouths, which send out feeder tentacles when food is in the water are likely to consume whole chunks of mysis shrimp, squid, etc. Corals with small mouths are likely to consume smaller fare, such as roe and species with tiny polyps will likely consume microscopic food such as phytoplankton. Most of my corals will do just fine with the excess food they get from zooxanthellae’s photosynthesis and some chunks of food they grab while the fish are eating. Non-photosynthetic species require multiple feedings per week with oyster eggs, rotifers or phytoplankton while all will benefit with a once weekly feeding of mixed coral food (phytoplankton, roe, rotifers, etc). It’s of little value (given my stock list) to distribution feed planktonic coral foods such as Reef Roids or Reef Chili, as it isn’t enough for most of the species and is unlikely to be grabbed by the others. In my case, distribution feeding on any level (for the corals) is likely only to raise nutrients. The best bet is to let the corals grab what they can during fish feedings and conduct a controlled target feed once or twice during each week.


· Maxima clams

· Multiple rose bubble tipped anemones

· Multiple gorgonians

· Several species of reef safe starfish

· Several species of reef safe shrimp

· Multiple herbivorous crabs

· Multiple omnivorous crabs, snails, etc

The clams within the tank will fare fine with excess food passed along via photosynthesis and supplementation with a small food such as oyster eggs. The same can be said for the gorgonians, which consume both oyster eggs and planktonic foods. Starfish do well when offered meaty and green fare in a fixed location where they can easily park themselves to digest. Herbivorous crabs do well under the same condition, while shrimp and other crabs prefer to grab fallen food from the sand bed and rocks. A mixture of planktonic, liquid and large foods will work best for all my tanks invertebrates.

Choosing foods and routine:

Luckily for aquarists, prepared fish foods have improved by leaps and bounds, offering the ability to feed multiple forms of reef life with a single food blend. For example, frozen blends often combine squid, fin-fish, roe and cyclopes with mysis shrimp. These are packaged in one frozen food, so as the food thaws in aquarium water, multiple food-stuff becomes available to the reef. I personally feed LRS Reef Frenzy, as it also includes fare for herbivorous fish. Even still, there needs to be supplementation with fish roe as well as phytoplankton and other small fare, depending on individual stocking lists.

I personally combine feedings of a mixed food like Reef Frenzy, with Reef Nutrition’s ROE, LRS’ fish eggs and several reef nutrition liquid diets. In fact, Reef Nutrition’s mysis feast and brine feast liquid are ideal for mixing with tank water to conduct target feedings for large meat eating corals. I have between 9-11 fish and coral foods on hand at any time, in order to ensure I have some diversity in my foods.

A good feeding routine begins with some sort of environmental signal to the fish that feeding is about to begin. I learned the importance of this while working in public aquaria, where any one aquarium could have over 100 species swimming within it, many with totally different feeding habits. There had to be a signal to each series of species that it was their turn to eat. Sharks were trained to react to brightly colored shapes placed in the water, while other fish species were trained to other environmental signals.

For the average home aquarium, I’ve found the best option to be shutting off the return pump and all circulation pumps. When the pumps shut off in my tank, you can immediately see the intensity of the reaction through the fish population. Mid-water and top level feeders should be given food first and I release some food into the water so it will start a slow descent toward the bottom. I carefully watch as the food is consumed. If mid-water feeders gobble it all up quickly, I keep putting more food into the water. Once they seem to level off, I switch on one circulation pump, so that some fallen food is stirred up and they have a chance to pick through it.

Rock scroungers and bottom level feeders are responsible for eating up the rest. It’s vital to gauge how much food is freely flowing through the water column and resting in nooks and crannies on the bottom. Pay careful attention to whether or not corals have grabbed any loose food. You only want to feed what the fish are eating and a bit more for inverts that comb the bottom for food. If there is ample food left uneaten and resting on the bottom, I cut off the circulation pump and let the scroungers pick away. If there isn’t, I shut the pump off and insert a bit more food.

After about 15 minutes of picking, I turn on all circulation pumps (but not the system’s main pump) and disbursement feed a small amount of fish roe, along with phytoplankton or oyster eggs. Fish with small mouths appreciate this, as do a host of filtering invertebrates within the tank.

This is a robust feeding regimen in and of itself, but is by no means complete. Feeding in this manner has to be controlled, meaning that one of the main points is to reduce waste. There shouldn’t be that much lying around and certainly not enough to sustain a diverse reef tank full of cleaner organisms. Most of these animals are primarily active at night, feeding on everything from uneaten food to fish waste, on down to biological sludge. It’s very difficult for slow moving snails, crabs, etc to get food while fish are in an eating frenzy. Innovative Marine makes a magnetic feeding grid that isn’t of much value for feeding fish, but works quite well for feeding invertebrates. Each evening, before the tank lights kick off, I usually pack the grid with mysis shrimp, seaweed and a mixed blend of marine fare. Each morning, the grid is clean. This approach protects the food to some degree from fish. They may pick at it, but if packed tightly and placed at the appropriate time, the majority of the food is eaten by other organisms in the tank.

The value of aiptasia?

Reef keepers work hard to rid their display tank of aiptasia anemones and for good reason. Left to populate a reef tank, aiptasia anemones sting corals and eventually over-run the display. However, aiptasia are quite efficient at gathering up uneaten food and other waste within the water column. Also, their reproduction and spread into the display tank can easily be thwarted with UV sterilization and ozone input. Robust feeding regimens are sure to add excess food to the water, likely in an amount greater than the tank’s entire collection of animals can consume. Yet, often lurking in our rock filled refugiums is an efficient food consumer, one that’s often killed at first sight.

Allowing aiptasia to proliferate in the sump isn’t a bad idea, if you are able to ensure they don’t migrate into the display tank. I recommend making the refugium the first sump chamber, right where water enters the sump. The following chamber should be outfitted with either UV sterilization or ozone, returning that water directly to the last chamber, before it is pumped back into the display. This can help kill off any aiptasia spawn, before it settles in the display tank. That said, aiptasia may appear in the display tank, so having some Joe’s Juice or a Mojana Wand handy isn’t a bad idea. Also, keeping a healthy population of peppermint shrimp is recommended.

Filtration and feeding:

While a conscious and capable feeding regimen promotes both adequate nutrition to reef inhabitants and balances nutrient load, it’s impossible to account for everything. Heavy, diverse feeding will create waste and it will put further strain on the biological filter within the tank. Furthermore, feeding an entire reef aquarium also means feeding the aerobic and anaerobic bacteria that assimilates waste. I recommend aquarists research and implement capable filtration, including the use of chemical media reactors, nitrate reactors, macro-algae reactors or any system solely designed to remove phosphate and nitrate. There is a lot of discussion within the hobby as to whether coral does best under limited nutrient conditions. I’ve seen aquarists claim that nitrates of around 10 ppm produce the best results, with phosphate levels of .03-.04 ppm being desirable. This has not been my experience as an aquarist.

I’ve found that nutrient levels (anything above 5 ppm nitrate and .01 ppm phosphate) ran in conjunction with reduced polyp extension, slower growth, deeper brown coloration (loss of colorful hues) and algae outbreaks. Again, this is merely what I’ve experienced. I’ve found it much easier to over-filter the water and maintain near un-detectable nutrient levels while supplementing corals with a robust diet, along with supplementation with amino-acids. This approach gives the aquarist some control over coral growth, coloration, etc. Methods of aquarium keeping such as zeolite filtration are specifically aimed at this type of environment.

A soluble carbon source can also play an important role in maintaining abundant de-nitrifying bacteria, while use of various nitrate reactors can encourage diversity within the aquarium’s de-nitrifying bacteria population. Aerobic bacteria get a food source anytime decaying food or waste produces ammonia, so it’s unlikely that most aquarists will need additional food to support healthy numbers. However, the periodic use of a nitrifying bacteria booster (or bacteria based aquarium cleaner) isn’t a bad idea.

Final thoughts:

Ever since I entered the marine aquarium hobby, I’ve paid special attention to feeding, along with looking into the contents of marine diets. My findings have pulled me away from using prepared diets such as flakes, pellets or anything made with a fishmeal base. Positive results have pointed me in the direction of diets made with natural seafood, specifically tailored to feed multiple reef organisms. The use of probiotics is a topic of discussion in the world of feeding. I find them beneficial and lab studies appear to as well. Probiotics can help maintain a balanced digestive system and perhaps relieve some of the digestive stress placed on our fish via collection, shipping and adjustment to captive life.
About author
Jeremy Gosnell has been a marine aquarist for nearly all his life. While studying sociology in college, Jeremy pursued becoming a professional scuba-diver, eventually serving as a coral reef biology science instructor for the Beautiful Oceans Academy based in Montreal, QB. This took him around the world, exploring some of the planet's incredibly diverse coral reefs.

Also, Jeremy worked on staff at the Pittsburgh Zoo's PBG Aquarium. He has contributed to a variety of aquarium-related publications over a 15 year career including, Freshwater and Marine Aquarium Magazine (FAMA), Aquarium Fish International (AFI), Fish Channel, Tropical Fish Hobbyist Magazine (TFH) and Today, he serves on the content review, editorial board of TFH Magazine in addition to providing original content for online and print publications.

He is also the author of novella Neptune's Garden and novel The Terminal, which won a merit of science fiction award at the 2015 Guadalajara International Book Fair.

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