person feeding a goldfish with flakes

How to Feed Fish

LAST UPDATED 29 March 2023

This article is written by Pet Circle veterinarian Dr Nicole Wynne Bsc BVMS MANZCVS (Unusual Pets)

The actual act of feeding fish is easy - just sprinkle some food into the water! However, there are lots of factors that go into the type of food, how much to feed, and how often to feed. A common mistake is to feed fish too often and too much, causing excessive waste to build up in the tank, ruining water quality. 

The species of fish you’re keeping also determines the best type of food to feed, and many common species of fish like goldfish, tetras, and cichlids have foods specially formulated for their needs. As many types of fish will have preferred water temperatures, this also determines the frequency and amount of feeding, as water temperature can directly affect speed and efficiency of digestion. 

Finally, just like dogs and cats, the quality of the food will have an impact on the health and vibrancy of your fish. Many types of fish require specific pigments and nutrients from their food to produce the iridescent colours that we love to see. A beautiful, radiant fish is also a healthy fish, and a tank full of beauties means that you’re smashing goals as a fish owner!

How often should I feed my fish?

fish in a tank

Feeding frequencies depend on whether your fish is herbivorous (a plant eater), carnivorous (a meat eater), or omnivorous (eats everything). Herbivorous fish usually eat small amounts throughout the day, omnivorous fish will also graze, but also take larger meals when they can get them, and carnivorous fish eat larger amounts less frequently. 

The appetite of your fish also depends on the water temperature. If you are keeping species that tolerate a wide range of temperatures, they will have a greater appetite when the water is warm, and a smaller appetite when the water is cool. Goldfish and koi are common species that tolerate a wide range of water temperatures, and can thrive from 15-25 degrees Celsius, and so are commonly kept in a pond set up.

Remember that fish don’t burn calories staying warm (like mammals), and so they don’t need as much food as a mammal of the same size. 

Small meals once to twice a day work well for most fish species, and any uneaten food that remains in the tank after 4-5 minutes should be removed and discarded. Uneaten food left in the tank will break down into toxic water pollutants like ammonia, jeopardising the health of your fish. Younger fish may benefit from feeding three times a day.

Fish also prefer a consistent feeding schedule, so you should resist the urge to give them extra feeds unless you are looking to induce spawning, or if your set up does experience warmer temperatures. 

How much should I feed my fish?

feeding a goldfish flaked food

Most fish will only be able to eat an amount of food about the size of their eyes! It makes sense when you think about the size of their little fish stomachs. This normally works out to be a pinch of food, or a few pellets or whatever they completely consume within 3-5 minutes. When feeding your fish, ensure that you spread the food around the aquarium so that everyone gets to eat. When starting out with your aquarium, take note of how much is eaten each time to minimise wastage and water soiling. 

Nets with fine mesh are ideal for removing uneaten food from your aquarium. However, even the finest mesh won’t be able to remove all uneaten food, and so any amount of excessive feeding will have a negative impact on water quality.

What type of food should I feed my fish?

feeding a goldfish granules

Fish food normally comes in flakes, pellets, granules, crisps, and wafers. You can even purchase frozen food or grow your own live feed. It is best to feed your fish a food that has specifically been formulated for their species. Also consider the style of feeder your fish are. Bottom feeders should be fed a sinkable food, top feeders a floating food, and middle feeders a floating or slowly sinking food. Most foods formulated for a particular species will take this behaviour into account. 

For foods that are designed for a wider range of fish, such as tropical fish food, read the ingredient list to ensure that it suits the species of fish you have. Many tropical fish foods are meat-based, and so herbivorous fish may require an algae or vegetable-based food instead. 

Flakes

Flakes are designed to be easy to eat and are suitable for fish that are too small to eat pellets. They also float, and are suitable for top or middle feeders. Although most quality flakes will be designed to hold together, they disperse in the water much more easily than pellets and will contribute to water fouling more.

Crisps

Similar to flakes, but with a thicker texture, this type of food holds together better and will gradually sink to the bottom of the tank, making them good for smaller fish that are middle to bottom feeders. Although they are sturdier, they will still foul water more easily than pellets.

Granules

Granules are very small, dense pellets that retain the benefits of pellets - easy to store and feed, denser texture and so less likely to foul water, but suitable for smaller fish. As they are denser than larger pellets, most granules will slowly sink to the bottom. However, they are still suitable for middle feeders as it usually takes them 1-2 minutes to sink. 

Pellets

Pellets come in both floating and sinking types, and they’re the most common type of fish food because they are easy to feed, cause less water fouling, and come in a range of pellet sizes, making them suitable for several species and lifestages. Uneaten pellets are particularly easy to remove from the tank with a net. 

Wafers

Wafers are a specialised sinking large pellet that are designed for bottom feeding grazers. Algae wafers are the most common for species like Plecostomus and there are omnivorous wafers for other bottom feeding grazers. They are specifically formulated to sink but still hold their shape, and are a great option for reducing fouling in the tank.

What kind of food should I feed my goldfish?

Goldfish love to eat and can do well on an appropriately sized floating to slowly sinking pellet, and there’s a pellet to suit almost every type of goldfish! The Hikari brand is the usual choice for many goldfish hobbyists and professional aquarists, and they even make diets specifically for more common goldfish like oranda and lionheads. They also make premium diets for all life stages of goldfish designed to enhance colour, minimising pollution and encourage growth. Although Goldfish Flakes are popular, bear in mind that they can be quite messy and contribute to poor water quality if not completely consumed. 

Goldfish should be fed once a day if kept in cooler temperatures, and 2-3 times a day if kept in warmer temperatures. Uneaten food should be removed from the tank or pond after 3-5 minutes. Some varieties of goldfish like the lionhead are slower swimmers and eaters, and so may take longer to eat. 

Goldfish also enjoy shelled peas, bloodworms, and brine shrimp as treats. Aquatic plants such as Ambulia are also a popular goldfish treat.  Remember to blanch any vegetables that you offer to your goldfish. 

What kind of food should I feed my koi?

Koi are naturally bottom feeders, but they do well with floating feed as well, and most pet koi will be used to feeding from floating food. While sinking pellets are more naturally suited to koi, it can be difficult to assess how well the koi are feeding with sinking pellets. It can also be difficult to remove uneaten food or visualise how much uneaten food is left after a feeding session. Many koi owners also enjoy seeing their fish come up for feeding, and it can be a great opportunity to check them over. 

Hikari are a premium manufacturer of koi diets and are the top choice of many professional breeders and hobbyists. Koi can be fed up to 3 times a day in warm weather, or as little as once a day in cold weather. Uneaten food should be removed after 5 minutes. If water temperatures in your area drop low enough (lower than 10 degrees Celsius) that your koi go into torpor, do not feed them until temperatures rise and they resume activity. 

What kind of food should I feed my betta or fighting fish?

These tiny, beautiful fish should be fed small meals 2-3 times a day. As a tropical fish, they will have a faster metabolism. It is also important that their water temperature is kept at 25-26 degrees Celsius to ensure they are able to digest food properly. Fighting fish also live in shallow water and are surface feeders, and so floating pellet foods are the best option as they are easy to feed in small amounts (2-3 pellets per feed), less likely to foul water, and easy for them to eat. 

Betta will also enjoy live food like brine shrimp and bloodworms as a treat. Ensure that all food is appropriately sized.

What kind of food should I feed my cichlid?

There are several species of cichlids kept in captivity, and most of them are omnivorous. Cichlid foods are a mix of animal protein and vegetable matter. Most species of cichlid do well with a slowly sinking pellet as they are middle feeders. As most cichlids are large enough to eat pellets, flakes and crisps are usually reserved for juveniles or smaller species.

Cichlids should be fed 2-3 times a day, with any excess food removed after 3-4 minutes. Fresh foods like bloodworms, shelled peas, and leafy greens can also be fed, and algae wafers can be offered occasionally for variety.

 


Further Reading

Want to read more? Check out our other articles:

Fish Tank Maintenance and Cleaning 101

How to Cycle Your Fish Tank

A Complete Guide to Setting Up Your Fish Tank

Choosing the Right Filter for Your Aquarium

Common Aquarium Problems and How to Solve Them

Shop All Aquarium Supplies Now

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Please note that as our vets have not examined your pet, any advice given is general in nature. If you believe your pet is unwell, please seek direct veterinary attention.