A fish must eat the right quantity and quality of food to stay healthy. The aquarium fish depends entirely on their keeper to provide them with an appropriate, well-balanced diet. The keeper must at least know that their fish needs protein to replace the body cells as they wear out, carbohydrates to provide energy and warmth, vitamins and minerals to help various organs to function properly and fight against diseases.
To supply the fish with a varied but balanced diet, the keeper must be able to source high-quality flake or pellet food and supplement it with good quality fresh live food. Make sure you buy only the quality flake or pellet food with a full display of analyzed ingredients manufactured by reputable manufacturers. In Singapore and Malaysia, there are many pellet foods packed in Japanese language plastic bags or containers containing nothing but high starch with low protein contents. There is live food (daphnia, bloodworms, and tubifex worms) available in the aquarium shops, but these are also the main source of bacteria and parasites entering the aquarium.
The best live food is the freshly hatched brine shrimps but they are very small and more suitable for small fish.
The next alternatives are freeze-dried food. The freeze-dried Krill, bloodworms, daphnia, and tubifex worms are good quality food in addition to the flake or pellet food. Do not use frozen food unless you know the source of supply because they could be unsold live worms frozen overnight.
A number of vitamins and minerals liquid supplements have recently appeared in the aquarium market. In their form, their therapeutic values are very doubtful. Firstly, not all vitamins and minerals are water-soluble. If they are insoluble in water, the fish is unable to absorb the contents through its gills — the way it absorbs oxygen; by simple diffusion.
Water-soluble vitamins such as ascorbic acid, pyridoxine, thiamine, choline, folic acid, riboflavin, pantothenic acid, B12, nicotinic acid, biotin, and water-diffusible ions such as carbonates, sulfates, sodium, calcium, phosphorus, potassium, iodine, and others, allow the fish absorb them through their gills tissue or skin. But the main setback is the high loss of potency of most water-soluble vitamins in aquarium water — some as high as 60% within 24 hours.
Oil-soluble vitamins( A, E, D, K) and insoluble minerals (copper, magnesium, iron, and most trace elements) will precipitate when diluted in water even when the best-formulated solvents are used. Thus you can see that the best way to feed your fish with vitamins and minerals is to incorporate them into a prepared diet and feed the fish regularly. The amount of vitamins and minerals required to vitalize your fish in liquid form is impractical and costly. Imagine pouring liquid vitamins and minerals into the ocean or even in an open cage in marine fish farming — and expect good results!
Aquarium fish should be fed regularly and in moderation. Feed at least twice a day and each time with as much food as they can consume in a few minutes. In a community, tanks make sure that the bottom feeders are not left without food because other feeders might have taken all the food before it sinks to the bottom. If you happen to keep a special type of fish, make sure you know what type of food it prefers otherwise it may starve to death.
Do not overfeed. The uneaten food will decay in the aquarium and cause pollution and fouling of the tank.