Feeding Marine Fish
Feeding the fish in the aquarium, and also shrimps if kept, is one of the most pleasurable parts of keeping a seawater aquarium. This is probably because of the direct interaction between the aquarist and fish. Some fish can become so tame that they will rise and take food from the fingers. This heart warming trick is often done by cleaner shrimps as well - in fact place a hand in the aquarium and they will often climb on the hand to see if they can find a morsel to eat. Movements outside the aquarium can cause the fish to respond and hang about the usual feeding area in the hope of food. This latter should be resisted, the fish are not starving, it is an automatic response after a while in the aquarium.
This brings me on to an important point. The action of feeding is, unfortunately, one that can bring trouble, particularly with newcomers to the hobby. Overfeeding! It is easily done, and must be avoided. Overfeeding can upset the water parameters. Nitrate (NO3) and phosphate (PO4) are mainly introduced through food. So pollution through overfeeding should be avoided. If the aquarium is fitted with a DSB (deep sand bed), or a denitrator, or has algae growing, the problem can be minimised. However, whatever the equipment, overfeeding is bad. It goes without saying that the fish also need enough food.
Fish in the wild for the most part feed little and continuously during the day. This can be seen in the aquarium, the fish moving about t5he rocks looking for food or hanging in the current watching for a morsel to float along. So it would seem sensible to feed a little often during the day. This is correct, it is the best way and is often recommended.
Unfortunately, the lifestyle of the vast majority of aquarists makes this impossible. The need to go to work, for example. It doesn’t matter, the fish can still be fed successfully and they will remain healthy. Feeding fish twice a day is fine, provided it is done properly. This means the fish can be fed before work, and later on the return from work. In an older aquarium, fish will often find edible items, but not enough to sustain them. Fish often have particular dietary additions that should be provided so that they are healthy. Surgeon fish, as an example, need algae. There may be some in the aquarium but is this enough? Dried algae can be obtained in sheets, and some put in each day using a suitable anchor such as an algae clip. Know what your fish would eat naturally, and how (from a rock surface or the water column)? It is important that they receive a good and varied diet so that they are not emaciated in appearance. Fish should be well filled between the ’shoulders’ and generally be rounded (remember that some fish are naturally more thin. If in any doubt have a look at a picture in a reference book or on the internet).
What to feed? There are many types of fish food available to the marine aquarist. Flake is one of these and it is probable that flake is the main food of the majority of aquarium fish. There are various types of frozen fish food available, two of the main ones used being brine shrimp and mysis shrimp. In addition, there are freeze dried foods and others. In this case let’s look at frozen brine and mysis shrimp, also flake.
Flake Food. The flake that is bought should be marked that it is for marine fish. Use flakes from different manufacturers at different feedings if desired. The flakes are rich and contain the needs of the fish. Using some small tweezers, take out an amount of flake that the aquarist thinks will be sufficient for the number of fish. Put this into an eggcup, and add some RO (reverse osmosis) water to soak the flake. Using the tweezers, take out a small pinch of flake, it will be soggy and cling to the tweezers. Put the end of the tweezers into the seawater so the flake breaks free. Note how much has gone in. The fish will consume the flake with great gusto, chasing after it as it swirls in the water currents. When gone, they’ll be looking for more. Get another pinch with the tweezers, not too much. The fish will again attack the food. But some or possibly all may be losing interest. If some are losing interest, reduce the pinch size and put some more in. Is it quickly eaten? Or do the fish swim up and then ignore it? Feed less and less. Don’t hurry, give the fish plenty of time to chase the flakes down. Stop when overall the fish are not particularly interested, or better, a little before. The idea is to put flake in that the fish will eat quickly, and before it goes into rocks etc. Once the fish have been fed in this way on several occasions the aquarist will be aware of the amount of flake that will be required. If there is any flake in the eggcup at the end of the feeding exercise, throw it away, do not be tempted to put it into the aquarium. If during the feeding there isn’t enough, get some more and pre-soak it. Remember that the response of the fish to food will vary, so do not dump the overall amount into the aquarium at one go, even though the general amount that will be needed is known. Feed small amounts as described. It will then be reasonably certain that the food has mainly gone where it is intended, into the fish. Towards the end of a tin of flake, the flake is often very fragmented or even powdery. If this is the case, discard it and start with a new tin. The fish may ignore or miss a lot of very small particles, but it will still pollute.
Frozen Food (eg brine or mysis shrimp). Again, fish will chase these foods and consume them rapidly. These foods are not as nutritious as flake, but are definitely worth using nevertheless. Mysis is the more nutritious of the two. When buying them, obtain the variety marked ‘enriched’ which improves the situation. They are good for varying the diet and may also provide roughage. Frozen foods usually come in blister packs. Break open a blister and cut the contents when frozen into four. Replace into the freezer. When required, take out one of the quarters and defrost it in RO water. Do not defrost in a microwave. When the food is totally defrosted, drain off the water. Some aquarists rinse the food as well. Then place the food into the aquarium. The fish will be after it and it should disappear rapidly. If the fish still swim about looking for more, take another quarter, defrost it etc as before. Put it into the aquarium. Do the fish chase it and eat it all? Are they losing interest? Are any still apparently hungry? Put more in if required, but reduce even the quarter amount if only one or two seem interested. The aquarist will know how much frozen food the fish are likely to consume, but, as with flake, do not put it all in at once, feed it in small amounts.
There are many varieties of frozen food and it is recommended to try several in order to give the fish variety. Whatever the food, the principal of feeding remains the same as described.
Do not be afraid of underfeeding. If the fish do not eat enough, they will eat more at the next feeding.
Provide one feed of flake each day, either am or pm. The other feed can be a frozen food. As mentioned, to provide even more variety, different frozen foods can be fed each day, and flake can be from different manufacturers. Not all foods tried will be successful, so obviously stop with that type.
Many fish will mix in and obtain a sufficient share of food. However, be aware of the more timid ones that may not venture out too far from their cave. In that case, place food close to them (after the other fish have been fed) making sure the food supplied is not too large for their mouth. Flake and some frozen foods will not be suitable as the currents will move it away.
Do not be concerned if a day is missed because of other commitments, the fish will be hungrier when the food arrives. Do not attempt to compensate by feeding more food generally, feed as described.
As time passes the aquarist will find feeding as described very straightforward, and the feeding experience will be very pleasurable without endangering the overall aquarium habitat.
Visit the ‘Salt Water Aquarium’ website if you are interested in learning more about the saltwater aquarium hobby.
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