What Do Fish Eat? (Answered)

Keeping pet fish can be a complicated and time-consuming process. Between keeping your tank clean, maintaining a good environment, and ensuring your fish do not attack or eat each other keeping an aquarium is not for everyone.

One aspect of fish keeping that is often overlooked is what, when, and how to feed aquarium fish. Pet fish need more than the occasional sprinkling of fish flakes to live off of they need proper nutrition and a mixed diet.

Different species have different dietary needs with some living off of meat while others slurp algae off the bottom of the tank. Understanding how to feed your pet fish is key to keeping them happy and healthy.


What You Should Feed Your Fish?

Fish need protein, carbs, minerals, and vitamins the same as every other living animal. What they specifically need is different from other species and can even differ between species of fish but their basic needs remain the same. The most basic information you need to know about your fish’s diet is what type of food they eat.

Fish can be broken up like most animals into one of three diets, carnivores, herbivores, and omnivores. Carnivores eat mostly meat while herbivores eat mostly plants and omnivores can eat both. Each type of diet has its own nutritional needs which you need to keep in mind while feeding them.

Most carnivores require a diet of between 45% to 70% protein along with fats and a small number of carbs. These can come from plants but should only be in a small amount. Herbivores on the other hand require large amounts of plant matter such as algae. You should know that very few fish are complete herbivores and most will require a small amount of meat in their diet. Omnivores can eat both plants and meat in equal measure but their diet should be varied to keep healthy.

Another factor to keep in mind is how your fish eat in the wild and how that will affect their feeding habits in a tank environment. Fish often swim and feed at specific levels in the water, surface, mid-water, and bottom. Fish will occasionally cross these boundaries to feed but are generally more comfortable feeding at their level, especially if they are a shy and peaceful species. Consider where your food will land when picking foods for your pet fish.

Finally, you should consider the size of your fish when you are picking their foods. Smaller fish have bigger appetites but also smaller mouths so make sure any food you give them is small and soft enough for them to chew. Larger fish have comparatively smaller appetites but much bigger mouths so they can eat larger foods.

Types of Fish Food

There are many varieties of fish food on the market for a tank or aquarium owner. These foods come in a wide range of forms each with their benefits and nutritional values. In order to make sure your fish are getting the best food possible consider the types of foods listed below and be sure to keep their diet varied.

The most common type of fish food on the market is dried foods with flakes being the widest known example. Dry foods also come in pellets, grains, and discs with varieties that float on the surface or sink to the bottom of the tank. Dry foods are primarily made of meat so they work best for carnivores and omnivores but herbivores can eat them if supplemented with plants and other foods. Some pet stores may carry algae-based dry foods that are better for herbivores.

What type of live food you get depends heavily on the type of fish you have as live bait and plants both count as living food. Live meaty foods such as feeder fish and brine shrimp are a good choice for larger and more predatory fish. Edible live plants such as java moss are an excellent choice for herbivores but they can also take fresh cut green vegetables such as lettuce and zucchini.

You need to be careful when feeding live foods to your fish as feeder fish and algae may contain diseases and parasites if they are not raised properly. A safer option for a fresh meal is frozen foods such as bloodworms or spirulina. Frozen foods are generally much safer than live food and some pet stores will carry frozen meat and plant-based foods.

How Much to Feed Your Fish

When feeding your fish it is important to keep in mind how much they need and give portions accordingly. As a general rule herbivores have larger appetites than carnivores or omnivores because they have smaller, simpler stomachs. If left alone with large amounts of food or live plants herbivores will feed, or even overfeed, throughout the day.

While underfeeding is a problem for fish and can pose serious health risks overfeeding is actually the more dangerous problem. If a fish is overfed then it will produce more waste while any food it does not eat sits and rots in the water. In an enclosed environment like a fish tank or aquarium, this can fill the water with harmful substances like ammonia and nitrates.

The best way to feed your fish is to see how much they can eat in 2-3 minutes. What they eat is the correct amount of food to give your fish. When they are done be sure to siphon any excess food out of the tank to prevent it from rotting and as a rule remember to feed based on the number of fish and not the size of the tank. Five goldfish in a 10-gallon tank eat the same amount of food as five goldfish in a 100-gallon tank.

How Often You Should Feed Your Fish

How often you need to feed your fish depends heavily on factors like their age, size, environment, and diet. Adult fish should be fed once or twice per day although if you are breaking up their meals into smaller portions you can feed them multiple times in a day. Young fish should be fed three or four times a day because they have a higher metabolism and need more food to grow.

Fish that are smaller and more activities such as danios and tetras have higher metabolisms and need to be fed more often. At the same time, larger and less active fish need less food and can go longer between meals because they have slower metabolisms. The temperature of the water around a fish also affects its metabolism with warmer waters giving fish higher metabolisms.

Since herbivores have smaller and simpler digestive tracks they need to feed more regularly. If left without food they will pick at any edible plants or algae in their tanks throughout the day. Due to this herbivores need to either be fed more often than carnivores or live plants should be left in the tank for them to eat during the day. Just remember to keep an eye on how much they are eating and how much they have left to eat.

When to Feed Your Fish

When feeding fish you have two options for how to set feeding times but you need to be consistent in your approach. On one hand, you can try to match the natural feeding time of your pet fish and feed them when they would eat in the wild. On the other hand, you can create your own feeding time and feed your fish every day at that time. No matter what method you use your fish will catch on to when feeding is and become more active around that time.

Generally speaking most fish eat either during the morning or the evening so if you are considering using natural feeding times this is a safe bet. It can also work as a made-up feeding time if it is easier for you to feed your pets right after you wake up or before you go to bed. If you feed this way make sure your aquarium light is on for at least 30 minutes either before a morning feeding and or after an evening feeding. This makes sure the fish are up and active enough to eat.

There are two exceptions to these rules when it comes to pet fish, non-carnivores, and nocturnal fish. Herbivores and some species of omnivores will eat off any edible plants in their tank throughout the day meaning they need less food if they have a steady source in their tank. Nocturnal fish do need regular feedings but can be fed in the evening before turning the lights off. This lets them eat overnight at their own pace but you have to be careful when feeding fish this way to avoid overfeeding.

What to do When You Don’t Have Fish Food

If you ever find that you do not have official fish food to give your pets you do not have to panic. There are many other foods you can give your fish that are safe to eat and provide the nutrition they need. The key is to understand what your fish need, what they can safely eat, and what nutrition each item provides them.

The safest and most effective option for herbivores is green, leafy vegetables such as lettuce, zucchini, and spinach. These foods are rich in the nutrients fish need and are a good way to keep their diet varied. Chopped up and boiled vegetables are the easiest for chew and digest to make sure to break up any greens you give your fish. Peas are also good for fish as long as you break off the hard outer skin and break them up into bite-size pieces.

If you have a carnivore then you can give them seafood items such as cod, tilapia, or shrimp. Do not give your fish oily or heavily seasoned fish this way as they are messy and can affect the tank environment. If you are using frozen seafood be sure to defrost it first before giving it to your fish.

Some stranger options for fish food are cooked rice or pasta and hardboiled egg yolks. Cooked rice and pasta can be chopped up into fine pieces and fed to fish as an alternative to regular fish food. Hardboiled egg yolks also make good fish food if cut up but they can break down in water so they should be given rarely to your treats.

When considering an alternative food to give your fish it is important to remember what they need to and cannot eat. For example, some fish may be allergic to certain substances so watch out for sluggish behavior after feedings. You should also be sure to keep your fish’s diet varied so they get the most nutrients possible. Alternate between standard foods and less standard foods for the best results.


Feeding your pet fish is more complicated and involved than simply sprinkling food flakes into their tank periodically. You need to keep careful track of what your fish need, how much they eat, when they eat, and many other factors.

Make sure to research what your fish can and cannot eat before you feed them something especially if it is not official fish food. This is the best way to protect your fish as well as keep them happy and healthy.

Leave a Comment