The feeding habits of marine fish are slightly different to those of freshwater fish – whilst freshwater fish may often hunt out food, marines often pick and graze. In the aquarium this means freshwater fish are more accustomed to waiting for foods and taking all they can at feed times, whilst marines still 'expect' food to be present and are more picky about what, when, and how much they feed on.
Feeding fishMarine fish need as varied diet as possible and many will not survive, or become ill, if given just one or two food types. Dried foods like flake or granules are still important and getting your fish to feed on these regularly is important for the provision of essential vitamins and minerals. To supplement dried foods, at least half the diet should be made up from frozen and fresh foods. Most good marine retailers will stock a wide variety of marine frozen foods, and you may need to experiment a bit to see which types your fish prefer.
Green foodsWhilst researching your fish before you buy, you may also find that some marines require 'green' foods – in nature these fish will constantly graze on marine algae. You can feed dried seaweed, frozen green foods, algae enriched foods, or lettuce leaves to these fish.
Feeding coralsCorals obtain much of their energy from the algae (zooxanthellae) that live within their bodies, and bright lighting is usually required for these algae to survive. Many corals are also 'filter feeders' and will catch food particles in the water. For these corals you may need to add a liquid food, which is a mixture of plankton and tiny marine organisms. Again, doing your research should tell you which corals need special feeding regimes.
Frequency of feedsSince many marine fish are designed to feed throughout the day on small quantities, they may not do well if only given one feed a day. Ideally you should aim to feed your fish up to three times a day or more on a variety of food types. Avoiding overfeeding becomes even more important when there are several feeds a day so make sure that any food added to the aquarium is eaten, none is leftover, and that you keep a close check on water conditions.