Food is required by all life for energy and general health. Lots of food of the wrong type may provide some energy but the contents will not supply the general needs of the life form. So it is important to feed the life in the marine aquarium the correct type of foods and at the same time not overfeed.
On the wild reef different life forms have different niches for food. There are predators, some general, some very specialized. There is life that eats a particular item, such as herbivores eating algae. There are also omnivores that will eat almost anything they come across, thus taking advantage of a wide range of food sources. The needs of these different types stay with them in the aquarium.
Again on the wild reef with its abundance of different life forms hardly anything goes to waste, there is something in the food chain that will clear it up. In addition, the huge volume of seawater over the wild reefs can ‘absorb’ any small amounts of food created pollution. This is not the case in the aquarium. Though modern systems attempt to replicate the wild reef as near as possible there isn’t a way that all the life variations can be represented. The very limited gallonage in an aquarium, even one considered to be very large, is subject to food pollution.
The aquarist can deal with algae by having herbivorous fish, crabs and snails present. Detritus can be dealt with to an extent in the same way. In a fish only system with live rock (FOWLR) and particularly in a reef system there should be a considerable number of minute creatures living among the rocks which no doubt will make use of excess food. Where does this excess food come from? In a FOWLR the aquarist is more than likely to stock the aquarium to its fish capacity. This is also usual in a reef system, though the fish stock is, or should be, lower. All of these fish, and any other creatures, need to receive supplemental feeding. The food that might be available in the aquarium is insufficient.
This supplemental food provided by the aquarist is usually either frozen or in flake form. There are variations but it is these two that are the main foods used. It is here that the potential danger lies. Novice aquarists more often than not do it – overfeed. Experienced aquarists, though more careful, ‘overfeed’ as it is usually impossible to ensure that all food is eaten and some inevitably end up in the rockwork. It is to be hoped that the tiny creatures in the rockwork will make use of it.
We should not be too hard on the novice aquarist who overfeeds. There are two reasons for this bad practice, the first is that the aquarist is concerned that enough food is available for the livestock, and the second is that feeding is a very pleasurable experience. So the error is made for the correct reasons.
A comment has been made about the restricted seawater capacity of an aquarium. One gram of flake food (say a teaspoon full) with a protein content of about 50% can convert to 336ppm (parts per million) nitrate*. In a reef aquarium the guideline for this type of aquarium is 10ppm or lower, and in a FOWLR as low as possible, preferably about the same. Though varying seawater gallonages should have some effect it is clear that pollution is a threat.
So what’s to be done? How can the pollution threat be reduced?
The aquarist should be providing a reasonably wide spectrum of supplementary food. As said, this is usually frozen and flake. It is obvious that to prevent pollution the amount of food of either type needs to be restricted, but how? How can the aquarist be happy that the livestock have eaten enough?
It is said quite often that fish and other marine life should be fed little and often, feeding only enough as can be completely consumed in two or three minutes. This is quite correct, first because reef life usually feeds continuously in the wild and second because the life will be hungry and more likely to chase down all the food.
Unfortunately, modern lifestyles do not allow ‘little and often’ feeding in many cases, as jobs call the aquarist away.
The first consideration is an auto-feeder. These feeders can be programmed to release a small amount of food into the aquarium at set intervals. Some are quite good, others not. The top of the aquarium must be open, and there needs to be an adequate area where the feeder can be securely fixed. Some aquarists see these auto feeders in the same way as, for example, automatic water top-up devices, in other words automate the aquarium system in all ways possible. All automation is good, correct? This is, in my opinion, wrong, some automation is good. Auto feeders though should be viewed as a potential way to feed little and often, nothing more.
These devices distribute flake food. For flake to be released it has to be completely dry, and the device is over the top of the aquarium in a damp area. This means that some of these devices fail from the start as the food becomes damp. At least there should be some kind of food drying mechanism – some feeders have a small fan that moves air through the food chambers.
Another problem with feeders is that they drop flake into the aquarium, and dry flake will float. If there are any weirs, overflows etc the food may go over these before being consumed.
Personally I don’t use them, preferring to feed direct twice daily. This means that the livestock will receive more food but with longer intervals between feedings. This doesn’t matter provided feeding is done carefully, and of course it fits in with the lifestyles of most aquarists.
The amount of food that will be consumed by the livestock will vary aquarium to aquarium as obviously the amount of livestock will vary. The aquarist needs to discover the quantity of each type of food, frozen and flake, which is required. This is easy to do.
Take frozen first. Frozen foods, such as brine or mysis shrimp, are usually supplied in blister packs made up of many blocks. The aquarist needs a very small container – an egg cup is ideal. Take one frozen food square from the pack and chop into four parts. One of these portions should be placed in the egg cup, and some aquarium seawater or RO (reverse osmosis) water added, enough to cover the food. Allow the portion to de-frost completely, so that the shrimps float free. Do not accelerate the process by using a heat source or a microwave, as it has been reported that this reduces the nutritional value of the food.
When fully de-frosted, pour off the liquid as far as possible. Then allow one half of the food to enter the aquarium. The food will be caught by the seawater currents and will move around the aquarium which should attract the fish. Once the food has gone the fish will probably continue swimming around eagerly looking for more. If so, repeat the process de-frosting more food if necessary, and continue to do so until the fish indicate they have had nearly enough. This is shown when the eagerness displayed has reduced.
The aquarist now has an indication of the amount that will be required for each feed. However, this doesn’t mean that the one or two or whatever blocks of food can be de-frosted and put in the aquarium all at once, this would present too much food to the fish and some would inevitably be missed. The aquarist can de-frost the full amount, but the food should still go into the aquarium in portions. This helps to ensure that it will all be eaten. Also, each feeding should be seen as an individual exercise, as sometimes fish can be less interested in food than at other times. It is better to underfeed than overfeed – if a little underfed the fish will probably be a little hungrier the next time. Any de-frosted food left over should not be re-frozen but discarded.
Flake food is dispensed in a similar manner. The flake should always be that which is described as suitable for marine life. The egg cup or similar is again required. Also, it is helpful to have some tweezers available, plastic if possible. Most fish, once they have seen other fish eat flake and have recognized it as food, will be attracted to it.
Take a good pinch of flake and place it in the egg cup. Try and ensure that the food is in flakes and avoid any very small bits as the fish will usually go for the larger flakes and the bits could be caught in the rock work. Put some seawater or RO water in the eggcup so that the flake goes soggy. Now take a very small pinch of flake with the tweezers – it will look awful and will cling to the tweezers. Release the wet flake into the aquarium where it will open up. The fish should chase it down and quickly consume it. They will no doubt swim around eager for more, so do the same thing again. As soon as this eagerness diminishes, stop feeding. Again, the aquarist has an indication of how much food is required. It may be that when using flake the fish lose their eagerness more quickly – this could be because the flakes can be quite large and the food is very nutritious. The aquarist should remember that flakes are very nutritious and less will usually be enough. Again, each feeding should be treated individually and a reduction in eagerness watched for. Any excess flakes should of course be thrown away.
With some fish, such as surgeons, there is a requirement for algae to keep them in good health. Though flake containing algae could be used, if there isn’t much algae of the correct type available in the aquarium the aquarist could put some in, in fact, this is a good practice. This algae is of the dried variety which is supplied in sheets, such as Nori. Health food stores often have this as well as pet retailers.
The algae sheet can be reduced in size according to the number of surgeon fish present, and then held in place against one of the viewing glasses with an algae magnet. It will move with the seawater currents and the fish will spend much time grazing on it, much to their benefit. It is a good idea to ensure there is algae present for such fish every other day – some aquarists keep it present every day. The aquarist needs to remove anything that is unused and likely to float off round the aquarium. It also needs to be remembered that feeding algae will reduce the appetite at feeding times of the fish that have eaten the algae.
Some fish, despite others eating well and giving a good example, do not overcome their shyness and natural instincts and remain in a part of the aquarium where food doesn’t reach. In this case, once the other fish have eaten, they need to be individually fed.
Feeding will produce some level of nitrate and phosphate even if done carefully. This increase in pollutants is dealt with by routine seawater changes. The changes offer advantages in addition to the dilution of pollutants and should be done in all aquariums. Some bio-filtration methods will generally deal with nitrate, such as live rock. Nevertheless, routine seawater changes should be completed.
Feeding carefully reduces pollution increases that can only be good for the live stock, which in turn are properly and sufficiently fed. Also, that most important aspect of feeding is still present – the aquarist’s enjoyment.
(*Reference: Baensch ‘Marine Atlas.’ Helmut Debelius & Hans A. Baensch)