Feeding saltwater fish
Different fish have different diets
Saltwater fish food is not as easy to get right as for freshwater fish. Depending on the type of marine fish you have, they will have different feeding needs. There are the seafood eaters who will require bits of fish or seafood tidbits. Then there are the plankton feeders who need to be fed with small foods such as baby brine shrimp, frozen cyclops and mysis shrimp. plankton feeders will need to be fed many times a day. If you supplement their diet with pellets these will have to be crumbled into the tank so that they can pick up the pieces.
Then there there are fish that feed on plant life such as seaweed and will need to be fed with greens from the kitchen and algae. And finally there are the algae grazers who will need a diet that is mostly algae. All vegetarian food will try to eat throughout the day so food must be made available throughout the day for them.
Your first job is to find out what your particular fish eats then set about buying or obtaining the foods they need. Some fish will not readily take to dried foods so you will have to rely on live foods and plant matter.
Some fish such as blennies are bottom feeders and search for organisms through the mulm at the bottom of the aquarium. They may feed off uneaten food left by other fish. Take care to see that these types of fish get properly fed. You may need to feed them directly with sinking pellets for them to find.
The fish that eat meat and that includes carnivores and omnivores will eat most forms of seafood from your fishmongers such as sea fish, prawns, mussels. Always chop these up into bite size pieces. For fish like tangs the pieces need to be very small because they tend to eat small life forms. Always blanch the seafood in boiling water for 1 minute to kill off any potential sea borne parasite.
Various recommended saltwater fish foods
Algae sheets such as nori which is a japanese food available in delicatessans is a great food to feed saltwater algae eating fish. When it is placed in the aquarium you will see all the vegetarian fish go into a feeding frenzy for it. It contains many essential micro-nutrients that are not available within garden greens such as romaine lettuce and spinach. So must be provided as a supplement.
All fish in the wild eat live food or fresh vegetable matter. Many wild caught fish will not take to dried foods so must be fed live foods such as brine shrimp and algae. However, many fish can be persuaded to eat chopped vegetables such as romaine lettuce and other greens. Dip the leaves into boiling water for 1 minute so that they become soft. Seaweed in the sea is usually soft so softening greens will simulate seaweed texture.
Other foods for saltwater fish foods
Some saltwater fish may take dried foods or even frozen foods. You can soak the defrosted frozen foods or dried foods in a multivitamin supplement for saltwater fish. This will ensure that your fish will get any vitamins that may be lacking in the diet you provide.
Frozen saltwater fish foods are available such as krill, mysis shrimp or cyclops. These should be defrosted thoroughly before being fed to the fish. If your fish take to this then your job will be much easier. But there is no reason to not also supplement their diet with seafood scraps from the supermarket or fishmonger.
Dried foods are not really recommended because of the lack of essential micronutrients that is available in live and fresh food. On saying that some fish keepers do get away with it. As long as you soak the dried food in a good quality saltwater fish vitamin supplement and top up their diet with some seafood tidbits and algae then you should be able to get away with feeding dried food. With dried foods you need to be extra vigilant and remove any scraps of food that fall to the floor and remain uneaten at the bottom of your aquarium.
Make your own saltwater fish food
If you can set up a small saltwater algae tank on a sunny window spot then great. Your algae eating fish can eat fresh organic algae, the perfect food that they would find in the wild. When doing a water change or just removing water from the main aquarium, do not throw it away but use it to top up your algae tank. The algae will grow well from the fish manure. If you can get some small shrimps or other minute invertebrates growing in the algae aquarium then all the better. Your omnivorous fish will love the tidbits of livefood found in the algae.
Place sheet rocks in the algae aquarium so that algae can attach itself. Then move these rocks to the main aquarium for feeding. When the algae has been stripped away move the rocks back to the algae aquarium.
Growing Brine shrimp or other shrimp in a hatchery
You can hatch out and grow brine shrimp in a separate small tank. Use a sponge filter powered by an air pump. Keep the water heated up to 80F. The tank should be placed on a sunny window sill. Pour in your brine shrimp eggs and wait for them to hatch. After hatching they take a days to eat off their yolk sacs so should not be fed immediately. Feed the shrimp with yeast, wheat flour, soybean powder, or egg yolk. Do regular water changes to keep the tank clean. The salinity for brine shrimp should by at 1.018 specific gravity. If you look after the shrimp well then they should grow and breed providing you with a continuous supply of shrimps. Gut loading the brine shrimp before feeding your fish is a good idea. This is just means feeding vitamin rich nutritious food to the brine shrimp for a couple of days before you feed your fish.