The Aquarium and Pond Active Online Publication

Mastering Freshwater Aquarium Ecosystems

Table of Contents

  1. COVER
  14. ROCKS
  15. WOOD
  16. PLANTS

Fish Food and Feeding

Fish primarily have high protein diets. Even fish that graze on algae receive protein from the bacteria and small microbes they ingest with the algae. When selecting food for your fish a food high in protein will be the best for conditioning, breeding, and growth.

Frozen, fresh, and live foods will have the highest protein content. Frozen food comes in many varieties for fish fry to large cichlids, pacus, and arowanas. For larger fish the fish market is a good place to find food like fresh fish and shrimp. Nori seaweed that is used for making sushi rolls is an excellent food for fish that like algae in their diet.

Protein content in dry flake and pelleted foods is highly variable. Dry food can have fish or krill as a primary ingredient. Krill based foods have natural color enhancer, and fish fed on this type of food will often have more vibrant color than fish fed fish based dry foods. Dry foods use wheat or rice as a filler and thus have lower protein content than most fresh and frozen foods.

When feeding your fish, a general rule that is often used, is not feed any more than they can consume in five minutes. This does not hold true in all cases. Discus are slow eaters and it may take them 15 minutes to fill up. You should also make sure enough food drifts down to the bottom for any bottom feed loaches and catfish.

If you are changing the type of food you are feeding your fish you should feed them the new food only in small quantities, as it often takes a week or longer for fish to become accustomed to the new food.


Bloodworms are red colored freshwater larvae of midges. They are most often sold in the frozen form. Bloodworms are an excellent supplementary food you can feed your fish either live or frozen.


Glassworms are nearly transparent insects that live in the water in the larval stage. Glassworms are most often sold in the frozen form. Glassworms are an excellent supplementary food you can feed your fish either live or frozen.

Brine Shrimp

Brine shrimp are small shrimp that live in saltwater. These shrimp are approximately ¼ inch long when adults. Brine shrimp are the most common frozen and live food fed to aquarium fish. They are an excellent staple diet food for most fish.

Newly Hatched Brine Shrimp
Brine Shrimp Eggs
Brine shrimp eggs can be hatched out in 24 hours and fed to fish fry. Photo from Brine Shrimp Direct.

Newly hatched brine shrimp are fed to young fish for the first 2 to 3 weeks of their life. You can buy dry brine shrimp eggs in a vial or can, and hatch them yourself in less than 24 hours in a jar of aerated saltwater. It is best to start a new batch every day when raising fish. Newly hatched brine shrimp lose their nutritional value quickly after they are more than 24 hours old, therefore try to feed them all to fish fry within 24 hours after they have hatched.

Boiled Spinach

Spinach is an excellent food for fish that like to eat algae and plants. Many fish that are primarily carnivores will also will eat spinach after it has been boiled. To prepare spinach for feeding, first wash the spinach, then strip off the leafy portions and boil for 10 to 15 minutes. Then dump the spinach into a strainer and run cold water over it till it is cold to the touch, then place the spinach in a ziplock baggy and flatten it out so it is not more a ¼ of an inch, and place in the freezer. You can feed the spinach in two ways, you can break off a chunk at a time and feed it to large fish and sucker mouth catfish, or for smaller fish you can use a cheese grater to create small pieces for small fish like mollies and guppies.

Romaine lettuce

Fresh romaine lettuce is popular food with many Central American cichlids, mbuna, and Tropheus cichlids. Pacus, silver dollars, plecostomus, goldfish, and koi enjoy grazing on romaine lettuce daily.


Zucchini is a popular food for plecostomus. It can sliced and served fresh or blanched. Some hobbyist remove the skin before feeding, but others remove the skin from the tank once the flesh has been eaten.

Beef Heart

Beef heart is an excellent food for many fish. Young fish that are fed beef heart grow rapidly. You can buy beef heart already prepared for feeding to the in frozen packs (usually in cubes), or you can prepare your own from the beef heart you can buy at the supermarket.

Nori Seaweed
Swordtails eating nori seaweed
Swordtails as well as other livebearers can all benefit from nori seaweed being part of their diet.

Nori seaweed that is used to wrap sushi is an excellent food for many species of freshwater fish. Many cichlids will eat nori, as well as livebearers. It is a excellent food that is about 1/3 protein and provides many vitamins.


Plankton is usually sold in frozen or freeze dried forms. They usually consist of shrimp that are about ½ (6 mm) to ¾ of an inch (9 mm) and about 3/16 of an inch wide (5 mm). These shrimp are an excellent food for many medium large carnivorous fish like severums (Heros severus) and texas cichlids (Herichthys cyanoguttatus). Plankton are high in protein and are a good color enhancer.

Mysis Shrimp

Mysis Shrimp are a good high protein food for fish like angelfish, convict cichlids (Amatitlania nigrofasciata), silver dollars (Metynnis sp., Myleus sp., Myloplus sp., Mylossoma sp.), pearl gouramis (Trichopodus leerii), malawi cichlids, and tanganyikan cichlids. Mysis shrimp are available in frozen and freeze dried forms.


Krill are shrimp that are about an inch long and a ¼ inch (6 mm) wide. These shrimp are an excellent food for large fish like oscars and midas (red devil) cichlids (Amphilophus citrinellus). They are sold frozen in flat packs or freeze dried. Krill are a very good color enhancer, and because of this, it is often used a primary ingredient in flake and pellet food.


Fish from the supermarket are an often overlooked by aquarium hobbyist as food for many larger fish. Cut the fish up in small pieces for the fish to eat. If your fish except filleted fish, you've found a cheap and safer alternative to feeder fish. Fish fillet can be cut it into small pieces and frozen in a ziplock bag and then thawed before feeding.

Live Red Worms (Tubifex) and Blackworms

Live redworms (tubifex) and blackworms are aquatic worms that live in the substrate. Tubifex and blackworms are a high protein food for fish. They can be used to bring fish into breeding condition. Tubifex and blackworms can sometimes get finicky fish to feed in captivity. They can also be used to aid in natural nitrate reduction by helping with slow water turnover in the substrate.

Unfortunately, tubifex and blackworms often carry parasites that can be transferred to fish. It is common for discus that are fed blackworms to be infested with tapeworms. Not all fish appear to be as susceptible to these parasites as discus.

Dry Foods

Flake food and pelleted foods are very popular foods, even though they often say staple food on the container, they should not be the only food you feed your fish. Fish that are fed dry food exclusively grow slowly, often will not reach spawning condition, and are often stunted. Flake and pelleted food should only be considered a supplement and not a staple. Flake and pelleted food does have vitamins that are needed for prolonged health of your fish. A diet of frozen food and flake food is a good way to insure prolonged fish health.

Ingredients can vary drastically from the different manufacturers. Some dry foods contain phosphate, which if fed often can lead to excessive algae grown in the aquarium.

Live Feeder Fish

Goldfish, guppies, and mosquito fish are the most common feeder fish available. Feeder fish are a good food for your fish, but there are some drawbacks. Feeder fish can introduce disease to the aquarium. Every time you feed live fish to the aquarium you run the risk of introducing parasites, bacteria, and viruses.

It is recommend that you do not feed your fish feeder fish unless they do not except any other types of prepared food. Most large fish that eat feeder fish will also eat pelleted food, frozen krill, frozen plankton, fresh fish, and fresh shrimp.