As you may expect, different fish have different diets. Commercial foods contain more nasty things than you may know about, and some fish have very specific dietary requirements.
So how do you choose what food to feed? This in-depth article covers it all. (Including those hard to pronounce things on the ingredients list you don’t recognize!)
Types of Fish
In general, there are carnivores (fish that eat animal matter), omnivores (fish that eat both animal and plant matter), and herbivores (fish that eat plant matter). But there are many specialists. For example
- In the wild, Oscars eat mainly snails and invertebrates, eating fish only when possible or on occasion.
- Bettas are carnivores, but more specifically they are insectivores. These are animals that eat entirely invertebrates, in this case insect larvae or any that are unfortunate enough to hit the surface of the water.
- Oto cats are strict herbivores, requiring live algae in their diet. This makes them limnivores.
- Gar eat entirely fish, thus making them a piscivore.
- Red tailed catfish are decidedly biased tword eating fish and shrimp but they are known to eat fallen fruit as well.
Obviously, since there are so many different types of fish there are many types of fish food out there. Not only do we have to keep the fish’s diet in mind, we have to think about how they eat.
Methods of Eating
In general, there are top feeding fish, middle feeding fish, bottom feeding fish, and grazers.
- Top Feeding Fish: Bettas, gouramis, hatchetfish, and African butterfly fish all look to the top to feed.
- Middle Feeding Fish: Tetras, barbs, South American cichlids, Damsels, Clowns, etc. all feed in the middle of the water column.
- Bottom Feeding Fish: Corydoras, loaches, and Jurapari all sift around the aquarium floor for food.
- Grazers: Loricariidae catfish, some loaches, tangs, some African cichlids, and many blennys graze for food on surfaces in your aquarium.
So what type of food is best for each type of fish?
Aquarium Fish Food Types
1. Dry Commercial Foods
When choosing commercial foods it is important to look at the ingredients list. They are listed by weight before the food is cooked, so you don’t want to see much “filler”. Filler is stuff that is cheaper than actual meat or plant matter, but still technically fits into a fish’s diet.
You also want as few carbohydrates as possible. Things like potato are used to help a fish feel full, however it does not provide much nutrition and do not spare protein for tissue building. The energy is also not stored by fish, which is why fish on a flake/dry food diet always act like they’re hungry.
So let’s look at some of the more popular ingredients.
The bad (ish)
- Wheat flour is a source of carbohydrates, which as we previously discussed is not very good for fish.
- Soybean meal is high in protein but also carbohydrates and phyto-estrogen. It is not very desirable compared to other sources of protein in my opinion, though it is highly used.
- Wheat gluten, used mainly as a binder.
- Feeding oat meal, another big carb.
- Potato protein, more carbs.
- Sorbitol, made from corn syrup.
- Inositol, more carbohydrates, though not a sugar.
2. Freeze Dried Food
Freeze drying has been used to preserve foods for a long time. It is the process of rapidly freezing a food then reducing the surrounding pressure to remove the frozen water by sublimation. This preserves the food for a very long time. However, you do loose some vitamins in the process.
(pictured: freeze dried krill)
Freeze dried food is also more dense, packing more calories in a smaller amount of space.
Freeze dried foods should be soaked in water before feeding to aid in digestion and help prevent swim bladder problems. They are actually good food when used as variety, however since frozen foods and live foods are readily available you should choose them over freeze dried.
3. Vacation Blocks
Vacation blocks, or vacation feeders, are foods that are put into the aquarium and are supposed to feed the fish for an extended period of time, usually a few days or a week.
However, they are made almost entirely of either calcium sulfate or something like agar agar. They hold very little actual food, thus giving little nutrition. In fact, many fish do not recognize the item as food and end up not eating anyway as the block dissolves into the water, fouling it.
Healthy adult fish, or at leas the majority of commonly kept species, can easily go a week without eating. Many people have had experience going even longer without food without any problems. So it is usually wiser to just skip the vacation food and not risk loosing your fish.
4. Commercial Gel Foods
Gel foods are typically made of the same ingredients that dry food is made of, only with fewer preservatives. It is bound by Carob bean gum (locust bean gum), agar agar, or gelatin.
Quality varies by brand, but some are certainly nutritious enough to consider a good staple for many fish. Some are sold frozen, some room temperature, and others are a dry powder you mix with water.
This type of food has a higher shelf life than flaked food (when frozen, up to 6 months). If the right brand is chosen, this is a great choice for food.
5. Frozen Foods
Frozen foods are whole and blended frozen food items, either by themselves or mixed with other ingredients.
There is frozen brine shrimp, bloodworms, glassworms, mysis shrimp, daphnia, krill, squid, crab, cyclops, and more.
There are omnivore and herbivore foods as well that include red and green algae, romaine lettuce, spinach, etc.
All of these are highly nutritious because a lot of the food is left whole and uncooked. Freezing does destroy a negligible amount of vitamins, but care should be taken to ensure the food is not freezer burnt.
Overall, frozen foods should always be incorporated into the diet if possible. They help mimic a natural diet and provide variety to the animals diet.
Frozen foods should be considered very high quality, and if you know what you are doing, a fish can be healthy and happy on a diet composed of entirely frozen, live, and fresh food. Before fish food and freeze drying was invented, this was all fish were fed!
6. Live Foods
Live foods are just that, alive! They retain all of their original nutrition but do have some drawbacks as well. Some live food should be considered extremely nutritious and always be given preference! Others, however, should always be avoided.
Live foods like blackworms, bloodworms, daphnia, brine shrimp, ghost shrimp, cyclops, copepods, etc.are all good choices for many fish.
(photo credit: Oliver Lucanus)
They differ vasty in sizes though so look that up before getting them. Example: Daphnia are very small and fed mainly to fry and fish with tiny mouths, mysis shrimp are medium sized and great for 3-5” fish.
- Not cooked or frozen, so no nutrition is lost. Extremely nutritious!
- Moving food stimulated a fishes appetite, especially picky or wild caught fish!
- It gives mental stimulation to the fish to be able to hunt.
- Invertebrates feel no pain, therefore removing some moral issues with live feeding.
- Some things, like brine shrimp, vinegar eels, and microworms can be grown at home.
- Some foods, like blackworms, can come from filthy sewage and nasty water. They can sometimes carry pathogens with them that can make your fish sick. Because of this, they should be purchased on the day of arrival and rinsed thoroughly.
- They have a finite shelf life, often for less than a month.
- They are not commonly carried, especially not by large chain stores.
- If you order online, which you may have to because of their availability, they can become out of your price range.
Some other live food considerations are crickets, silkworms, crabs, and snails.
7. Home Made Food
Home made food may be the best option for many fish keepers. It allows you to know exactly what goes into your food and where it came from. However, it can also lead to deficiencies if you are not educated on fish nutrition.
Still, home made foods are a good compliment to a diet of dry foods. Most home made food is a mix of fresh or frozen ingredients held together with a binder, typically gelatin or agar agar. Recipes vary depending on what fish is being fed, obviously, but here are some you may want to try at home.
For more recipes, read: DIY: 5 Simple Fish Food Recipes
Common Mistakes in Fish Diet
Many fish are fed inadequate diets, resulting in stunted growths, parasites, vitamin deficiencies, and worse! By far the worst fed fish I know of are cichlids.
So here are some commonly wrongly fed fish.
Sources and Guides
Editor’s Note: This article was written by our latest contributor here at Home Aquaria, Victoria Murphy.
Victoria is a very active member of the fish community on Tumblr and we’re delighted to have her here on Home Aquaria. With a monster post like this, who wouldn’t be?
Join us in welcoming her in the comments section below or follow her on Tumblr here.