Feeding Marine Fish

Feeding marine fish and watching as they swim around competing for every morsel of food is one of the daily highlights for the saltwater aquarium hobbyist.

How much to feed you fish?

Feeding marine fish is a lot of fun.  But how much do you feed your fish?  A good general rule is to feed as much as they will consume in 3 minutes.

Fish need to be fed at least once every other day, but if you prefer to feed daily, limit the feedings to once a day, or light feedings twice a day . Although some aquarists with mature tanks with great populations of copepods choose to feed once every 2 or 3 days to keep nutrients low.

Feeding Marine Fish A Variety Of Foods

We have a huge array of foods to choose from these days with which to feed our fish.

feeding marine fish

Marine Fish Foods – Dry, Freeze Dried and Frozen

Marine fish flakes, pellets, freeze-dried, frozen and when available, live foods, ensure that we can easily give our fish a varied diet.

I personally prefer not to feed flake foods — it dissipates in the water too quickly and a lot of it goes uneaten, ending up in the nooks and crannies of the tank, degrading water quality.

When feeding marine fish pellets, I think it is good practice to soak the amount you are intending to feed in a tablespoon of aquarium water.  After 20 minutes, the pellets will have absorbed the water, swelling up to double their size.  This also softens the pellets and makes the fish go for them with gusto!  And because the quantity of food after soaking appears larger, it makes the aquarist think twice about throwing in the entire amount!

Enriching Pellets And Freeze-Dried Foods

Feeding marine fish foods enriched with highly unsaturated fatty acids (HUFA) and Vitamin C is extremely beneficial.  Selcon by American Marine is one such product that can be used to soak dry foods to boost its nutritional value.  The stabilized Vitamin C in Selcon is also beneficial to fish suffering from Head and Lateral Line Erosion (HLLE).

Selcon has been around for years and is trusted by professional aquarists involved in fish and seahorse breeding programs.  Live foods such as baby brine shrimp can also be ‘gut-loaded’ with Selcon to make them more nourishing.

It should be mentioned that protein skimmers will typically stop producing foam for around a day after feeding HUFA rich foods such as Selcon or Cyclopeeze.

Herbivorous Fish And Nori

If not fed at least once a day, herbivorous fish such as tangs will start to exhibit sunken abdomens if no algae is present in the aquarium for them to graze on.  This is no cause for alarm and nothing that some nori or dried Japanese seaweed from the sushi counter at the supermarket cannot fix.  But make it plain, non-spiced nori!

Feeding nori to herbivorous fish is much more nutritious than feeding terrestrial vegetables like fresh romaine lettuce or broccoli.  And it is also a lot cheaper.

Stock Less, Feed Less

It is better to under-stock your tank with fish during the first year.   Fewer fish means that less food will be required to keep your fish population well-fed.  It also means that we will not be burdening the fledgling nitrifying and denitrifying bacterial population in our tank.

feeding marine fish

An array of available marine fish foods

It should be noted that unlike fish, corals in general do not add much bioload to your tank.

Of course, if you’re stocking non-photosynthetic corals which require direct feeding  (such as tubastrea or sun corals), then these corals should be considered part of your overall bioload.

Feeding Marine Fish In A New Saltwater Aquarium

Any marine tank that is less than 2 years old is considered ‘new’.   The tank is still dependant on regular weekly, or at the very least fortnightly water changes of 10% to 15% to maintain water quality.

Feed carefully for the first year of your tank’s life — you’ll want to wait until your tank is mature enough.  A mature aquarium system is better able to process the ammonia produced from decaying, leftover food.

Resist The Urge To Overfeed!

In the wild, marine fish are constantly grazing and nibbling at anything that might look potentially edible.  In our captive aquariums, this behavior still persists, but because our fish have come to associate the presence of the aquarium keeper with chunks of food falling from the water’s surface, it may seem that they are constantly hungry when approached.

The novice aquarium keeper’s response to his ‘hungry’ fish is to throw in even more pellets, flakes and fresh foods.

Overfeeding And New Tank Syndrome

Couple overfeeding with an immature biological filter and you have the makings of a potential tank crash.  Sometimes referred to as New Tank Syndrome, uneaten food breaks down to ammonia and nitrite faster than the biological filter can convert it to nitrate.  New Tank Syndrome results in the death of all but the hardiest of fishes in an aquarium.

Overfeeding And Nuisance Algae

Feeding marine fish more than can consume leaves decaying, uneaten food in the tank — the source of common problems like elevated nitrates, phosphates and nuisance algae.

Once nuisance microalgae or hair algae takes over a tank it can be very difficult to remove as described in these page on Algae Control and Phosphates.

Automatic Fish Feeders

If you are extremely busy and are home at irregular hours, an automatic fish feeder will come in useful.  Simply put the dry food of your choice into the food compartment and set the timing intervals that you would like the food to be dispensed into the aquarium.  Feeding marine fish has never been easier!

When using an automatic fish feeder, use sinking food pellets instead of flakes — flakes will float and get into the overflows and into the sump before the fish have a chance at it.  The Eheim Everyday Fish Feeder is a particularly high quality unit.

If you are interested in keeping Mandarin Fish, you might want to also read:

Mandarin Fish | Care and Feeding

Read more about Aquarium Livestock:

How To Acclimate Fish

Quarantine Tank

Aggressive Fish

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