Fish Food and Protein Quality

Feeding Aquarium Fish

Do Not Over Feed

This is something told to most people who are planning to keep fish. It’s good advice, but is often misunderstood. Fish usually don’t over eat; overfeeding mostly means that the aquarium can’t cope with all the food. This situation is made much worse if some of the food is uneaten.

Signs and Effects of Overfeeding

People often ask me why their aquarium is cloudy. There are several possible causes. The first question is whether the cloudiness is white cloudiness or green. If it is green, the cause is probably algae. 

White cloudiness can also be caused by several things, but the most common one is overfeeding. The cloudiness is bacteria which are feeding off the excessive food. Most of the bacteria are not disease causing ones, but these conditions are not good for your fish.

Ammonia

Over feeding can cause a rapid build-up of Ammonia in the water. Ammonia can kill your fish.

Smell

A healthy aquarium has a pleasant smell. If it becomes unpleasant, this could be a sign of overfeeding, but also check to make sure there are no dead fish, snails or plants, etc.

How much Food to Give?

This is a question I'm asked a lot. If you are feeding flakes to your fish, generally they should have finished eating them in about two minutes. However, some fish eat faster than others, but if there is any left over after five minutes you have probably given too much.

With bigger food like algae wafers, the fish can’t completely eat them until they have softened a bit in the water. The same applies to larger pellets.

Live food is different. As long as it is of a type that stays alive in the aquarium, the fish can continue eating the live food for some time. If the food stays alive, it should not foul the water.

How Often Should I Feed my Fish?

This is another question a lot of people ask. In our shop the usual answer I give is once a day. This is not necessarily the ideal, but it is easy for most people to do. From the point of view of the fish, more frequent feeding is preferable, and I feed our fish more often. But if you do feed more frequently, it increases the chance of overfeeding.

What Sort of Food Should I Use?

When people ask me this, my answer has to depend on the type of fish. Generally, fish benefit from a variety of food. Do not just get one type of food and stick to it. Apart from making sure your fish get all the different nutrients they need, a variety of different forms of food is a good idea because the different fish in a community aquarium are adapted differently for eating different types of food.

Types of Food

There are many different forms that fish food can take. Here are a few of them.

Flakes

When fish food is mentioned, some people think of flakes. They are a convenient way of feeding your fish. A good quality flake can be a good basic food. Good quality fish food will normally have many different ingredients, not just a few. 

Wafers

There are a number of types of sinking wafer. These are mainly for bottom feeding fish, but most fish like them.

Pellets

Pellets are another form food can be given to your fish. In some cases, they have the advantage that it is possible to count how many you are giving your fish. 

When my young daughter was at primary school, we gave the school an aquarium. It moved from one room to another each year so my daughter could help supervise the feeding of the fish. A different child fed them each day, carefully counting out the correct number of pellets. We also gave the fish other food occasionally for variety.

Weekend and Vacation Feeders

These come in different forms, but the most common one is a plaster block with food embedded in it. In the classroom tank I mentioned above, each Friday a weekend feeder was put in. 

For each two-week holiday, a vacation feeder was used. The only time we had any trouble with this system was once when someone else thought the fish were hungry and put extra food in during one of the holidays. The fish survived, but the tank needed an extra cleaning after school resumed.

Frozen Food

There are many types of frozen fish food. The make we use and sell is the Fish Fuel Co brand. This is the most popular one in Australia. Unfortunately, this brand is not available in most countries. Of course, there are many other brands of frozen food and I don’t doubt that many of them are also excellent brands. We’re very lucky in South Australia because the Fish Fuel Co. is local.

There are different frozen foods for different groups of fish.  For example, one food is for Discus, and there is a Frozen Goldfish Food.

The most popular frozen food in our shop is frozen bloodworm.

Protein Quality

Crude Protein

On many foods, both for Humans and animals, the nutrient composition often contains things like Crude protein, Crude Fat and Crude Fibre. The word crude in this context refers to the method of determining and calculating the component referred to.

Protein contains about 16% Nitrogen. It’s not the only thing in food containing Nitrogen, but normally is the main one. Crude Protein is simply the percentage of Nitrogen multiplied by 6.25.

The phase Crude Protein doesn’t say anything about the quality of the protein.

Protein Quality
Protein is made up of Amino acids. There are several different types, including about 22 sorts commonly encountered. The exact number included depends on what organism you are considering.

A high-quality protein is one that contains all the essential Amino Acids for the type of animal concerned, in the correct proportions. Frequently, animal proteins are of higher quality than plant ones, but both animal and plant proteins vary a lot.

I’m a vegetarian, but I eat eggs and milk which both have very high quality protein. Vegans need to be more careful to balance their diet, both to include enough of all the vitamins, including vitamin B12, and to have all the Essential Amino Acids in it.

Essential Amino Acids
An Essential Amino Acid is one that the person or animal can’t make by itself from other Amino Acids. As you can see, the actual number of essential Amino Acids varies with different types of animal. Humans have 8 Essential Amino Acids. I think Horses have 10 Essential Amino Acids.
There are many different sorts of Fish and their Amino Acid requirements vary with the type.

Biological Value
This is similar to Protein Quality. The quality of a protein can often be improved by adding a different one. A very common example is when a meal has both a grain-based food and a legume. A couple of common examples spring to mind. Beans on toast has bread, made mainly from Wheat, a grain, and Beans, a legume. Another one is rice with peas.

As a general rule, a variety of food is better than just one. This applies to fish and other animals as well as to people.

Fish Food
A good quality fish food will have more than 20 different ingredients. In Australia, there was once a fish food made that had only 5 different ingredients. It was no good, and a lot of people had trouble with it. The company that made it makes some excellent products of other sorts, but clearly hadn’t done enough research into the nutritional requirements of fish.

Some other fish foods may also only contain a limited number of ingredients, but are much better than the fish food mentioned in the previous paragraph. These foods are generally not suitable as the only food for your fish, but can be a valuable part of a varied diet.