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Aquarium fish food – A detailed introduction

In order to keep the fish healthy and the aquarium water in perfect condition it´s important for you to learn the basic knowledge about the different types of fish food and the most suitable ones for each species. A healthy, varied, quality-ingredients food facilitates digestion and strengthens the fish immune system for coping with disease. There´s a wide range of foods which meet the nutritional needs of carnivores, herbivores and omnivores fish.

A basic fish diet should contain abundant nutrients like fats, proteins (helping growth), carbohydrates (energy source), vitamins and minerals (reinforcing the immune system), and fiber (helping the intestinal system as well as nutrient´s absorption).

Fish classification according to their diet

– Carnivores: they need a greater contribution of animal protein; they consume live animals such as worms, small crustaceans and insects.

– Herbivores: algae, leaves and fruit.

herbivorous fish eating leafHerbivorous fish

Image / “Elaine”.

– Detritivorous: algae, food waste and decaying organic remains.

– Omnivores: any type of food, whether plant or animal.

How should I feed them?

  • The food´s dosage is very important if you don´t want to disturb the biological balance with leftover food that isn´t eaten. You should observe daily the amount of food they eat in two minutes to maintain that dose.
  • The size of the food pieces should be in proportion to the fish mouth.
  • Divide the food into 2 doses per day.
  • Remove leftovers with a thin net.

Types of foods

There are three different types: a) dry food, b) live foods, and c) fresh food.

Dry foods

There´s a great variety of prepared dry foods which ensure a healthy and balanced diet. They´re sold as flakes, scales, powders, tablets and pellets, ensuring a high intake of vitamins and nutrients. Still, you should alternate it with other kinds of food to ensure that he gets ALL the vitamins.

aquarium fish food - dry foodsDry food for fish

Image / “Pinpin”.

Each type of industrial food is directed towards a particular group of species: some contain algae for herbivorous fish and others animal protein for carnivorous ones.

Live foods

They consist of animals and microorganisms that live in aquatic nature, providing a significant nutritional contribution which is rich in vitamins, protein and fiber, in greater quantities than those of dry foods. You should never catch any of these animals directly from nature to give them to the fish because they can be carriers of pathogens and cause disease. We recommend buying in stores from a reliable supplier that offers guarantees.

Live foods are subdivided into frozen and lyophilized.

Frozen live foods: these are living beings that have been captured in the wild before being frozen. Before giving them to the fish the following is recommended:

1) Defrost them in a glass filled with water from the aquarium (never do this inside the aquarium).

2) Wash them thoroughly with clean water in order to remove dirts and bacteria.

3) Once defrosted and clean, the fish can eat them. They should never eat food that hasn´t been defrosted because it can damage their digestive system.



Lyophilized live foods: lyophilization is a process by which the food is frozen in advance before being subjected to a strong desiccation by air vacuuming (water removal of 98%) that maintains its nutritional properties. The end result is a hard, porous substance from which any pathogenic organisms that may cause disease have been eliminated, and needs to be preserved in hermetically sealed containers.

Most common preys

– Mosquito larvae: a real high-protain delicacy for fish. However, we must be wary of very small fish or herbivores because they don´t tolerate them very well.

aquarium fish food - mosquito larvaeMosquito larvae


– Tubifex worms: aquatic worms that live in muddy, stagnant deep waters; they´re rich in protein, minerals and beta-carotene. Due to their high percentage of fat it´s recommended to give them only once a week. Commercial stores must ensure their good condition because they are carriers of parasites.

– Daphnias or freshwater fleas: small, oval-shaped crustaceans with less protein than larvae and worms.

aquarium fish food - daphniaDaphnia

Image / Chantal Wagner.

– Artemia Salina: foods high in protein and very low in fat, suitable for all types of fish.

– Mealworms: larvae of the flour beetle. They´re used to feed large fish, but don´t abuse of this food for its high level of fat.

Fresh food

Among the most used are vegetables (spinach, zucchini, raw potato) and meats (raw or cooked mussels, fish and small crustaceans). The good thing about this type of food is that it keeps vitamins intact, the bad thing is that it contaminates the water, hence increasing the risk of disease. To avoid this situation the water should be cleaned again and its conditions measured (such as pH, hardness, nitrites, nitrates and ammonia), to be sure that the biological balance is maintained.

Points to remember

  • In order to provide a balanced diet, it´s important to offer them different kinds of food. You can choose different brands also so that they get different flavors.
  • Buying quality foods will maintain the fish in good health.
  • Stress, fish overpopulation and fear can lead them to not eating well.

fish overpopulationFish overpopulation

Image / Jennifer Hughes. 

  • Food dispensers are very useful in case you have to be away for a long time.
  • It´s important not to mix large fish with small ones to avoid food competition, leaving the small fish hungry.